[From the U.S. Government Printing Office, www.gpo.gov]
j -4- E OREGON i IV IwA V '4W 611, It, @@w lot rL14 Aw QH1 05 Ti \X @-? (C- A BDI 10 0 lf@@@ U'@@7,74' ,_p A *!'- .07 P37 1985 kk A 0 THE AN INTRO INCLUDIN AND LIVING MA BY Tish Parmenter Robert Bailey STATE OF Victor Atiyeh, Gov DEPARTME James F. Ross, Director With special assis Oregon State Uni 1985 US DEPARTMENT OF COMMERCE Published 1985 by SPECIAL THANKS National Marine Fisheries Service Oregon Department of Land Conservation and Development Dale Evans, Portland Carla Stehr, Seattle Richard Merrick, Seattle 1175 Court St., N.E. The manuscript for The Oregon Oceanbook was edited by Sandy Salem, Oregon 97310 Ridlington, Oregon State University Sea Grant Communications, U.S. Fish and Wildlife Service Copyright 1985 by State of Oregon Corvallis. Her skillful and sharp-eyed services were made available Jay Watson Printed by Oregon State Printer, Salem, Oregon to the Oceanbook project through the cooperation and support of Pacific Marine Fisheries Commission Second printing, 1986 William Wick, Director, OSU Sea Grant Program, and James Larison, Russell Porter Sea Grant Communications Director. We extend our thanks for their Pacific Geoscience Center, Sidney, B.C. FUNDING kind assistance in providing this most valuable service. R. D. Hyndman The Oregon Oceanbook was prepared with funds from U.S. Department of Commerce, Oregon Coastal Zone Management Association, Inc. National Oceanic and Atmospheric Administration, Office of Ocean and Coastal Resource Jay Rasmussen Management, Outer Continental Shelf Participation Program (Sec. 308 (c)(2)); ACKNOWLEDGEMENTS State of Oregon, Department of Land Conservation and Development; The authors would like to acknowledge the many individuals who have contributed to The Columbia River Estuary Study Task F&ce The second printing of the Oceanbook was fundeiby a grant from the Office of Ocean and Oregon Oceanbook. Paul Benoit Coastal Resources, NOAA, U.S. Dept. of Commerce, Section 306, Coastal Zone Manage- The authors of the Oceanbook relied heavily upon marine science expertise at the OSU Wang Laboratories ment Program. School of Oceanography. These busy researchers and professors made time to review Pat O'Bryant (for keeping our word processor functioning) manuscripts, double-check facts, add information and find references. We could not have MAP SOURCES produced the Oceanbook without their kind assistance. Everett Hogue Base map of Juan de Fuca Plate Vern Kulm Jane Huyer Robert Smith Elizabeth Krebill Courtesy of R. D. Hyndman, Director, Pacific Geoscience Center, P.O. Box 6000, Sidney, Jim Good Frank Flynn Rob Holman Peter Howd British Columbia V8L 4132 William Pearcy Rick Brodeur Larry Small Range Bayer Gary Taghon James Harvey Charles Miller Willa Nehison Bathymetric Map of Oregon Continental Shelf David Stein Harold Batchelder Mark Brzezinski NOS Map 12042-12B, National Oceanographic and Atmospheric Administration, National Lynne Krasnow Paul Komar Carlos Lopez John Elliott Allen (Professor Emeritus, Department of Geology, Portland State University) Ocean Survey, Washington, D.C. Oregon State University Sea Grant Communications Ron LeValley Global Design Sandy Ridlington Joe Cone Courtesy of John Sherman, University of Washington, Department of Geography, Seattle, William Wick James Larison Washington University of Oregon ABOUT THE AUTHORS: Dan Varoujean (Oregon Institute of Marine Biology) Tish Parmenter grew up on the sunny side of the coastal fog belt north of San Francisco GRAPHICS, ILLUSTRATIONS AND DRAWINGS Dick Hildreth (Ocean and Coastal Law Center) and developed an early interest in the ocean and marine resources. After receiving her B.S. Robert Bailey Nancy Dahl in Conservation of Natural Resources from the University of California at Berkeley in 1977, Parmenter developed educational programs for the Oceanic Society and managed an Elizabeth Krebill (species drawings pp 7, 37, 39, 40, 41, 46-48, 51-53, 57, 63, 65-67) Oregon Department of Land Conservation and Development oyster culture facility at Tornales Bay, Calif., before graduate studies at Oregon State Mitch Rohse Don Oswalt Patty Snow University. While at OSU she served an internship as coastal resources planner for the BOOK DESIGN AND LAYOUT Bob Cortright Eldon Hout Al Burns Columbia River Estuary Study Team (CREST) in Astoria. She received her M.S. in Marine Robert Bailey Oregon Department of Geology and Mineral Industries Resources Management in 1984. Greg McMurray John Beaulieu Jerry Gray Robert Bailey is a native of Oregon's Coos County and grew up within earshot of the Pacific TYPESETTING Ocean in North Bend. He received a BSc. in Earth Science from Portland State University in State Printer, Salem, Oregon Oregon Department of Transportation 1968. He has taught junior high earth science, helped establish the land-use planning American Graphics, Portland, Oregon Pete Bond, Park Division program in Coos County, participated in development of a citizen involvement program Irish Setter, Portland, Oregon Oregon Department of Fish and Wildlife using portable video for Southwestern Oregon Community College, roamed eastern Rod Kaiser Dale Snow Gerry Lukas Oregon as field representative for the Department of Land Conservation and Development, PHOTO REPROGRAPHICS and worked for three years as senior planner for a Portland architectural firm. Since 1982, PhotoCraft, Inc., Portland, Oregon Robin Brown Bailey has been Outer Continental Shelf Coordinator for the Oregon Department of Land Printing Division, State of Oregon, Salem, Oregon Oregon Department of Environmental Quality Conservation and Development. Bruce Sutherland Randy Smith Larry Patterson PHOTOGRAPHIC SOURCES Ed Lynd Cover Photo: Oregon State University College of Oceanography photograph collection, Oregon Department of Energy Corvallis, Oregon, courtesy of Carlos Lopez. Scott Smith Satellite Photographs: U.S. Department of Commerce, National Oceanographic and Atmo- Army Corps of Engineers, Portland spheric Administration, National Climatic Center, Satellite Data Services Division, Wash- Steve Chesser Dan Hancock Jim Reese ington, D.C. 20233. U.S. Geological Survey, Menlo Park, California Electron Micrographs: Courtesy of Carla Stehr, National Oceanic and Atmospheric Admin- Dave Clague istration, National Marine Fisheries Service, Northwest and Alaska Fisheries Center, University of Washington College of Oceanography Electron Microscopy Lab, Seattle, Washington 98112. John Baross Ross Heath Geophysical Survey. Profile: Courtesy of Mike Bell, ARCO Exploration Company, Dallas, University of Washington Department of Geography Texas 75221. John Sherman Aerial Photographs of the Oregon Coast: Oregon Department of Transportation, Highway University of Washington Sea Grant Division, Salem, Oregon 97310. Patricia Peyton Alvin photograph: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts University of California Sea Grant, La Jolla 02543; photograph by Rod Catanach. Rosemary Amidei THE OREGON OC ANBOOK TABLE OF CONTENTS ONE Y Life and the Environment TWO 33 The Rocks THREE The Water THE OREGON OCEANBOOK TABLE OF CONTENTS INTRODUCTION 1 ONE MARINE ECOLOGY: 5 Life and the Environment TWO GEOLOGY: The Rocks 11 THREE OCEANOGRAPHY: 25 The Water FOUR PLANKTON: 35 The Drifters FIVE NEKTON: The Swimmers 43 SIX BENTHOS: 60 The Sea Floor SEVEN MARINE BIRDS AND MAMMALS: 69 Residents and Visitors APPENDIX 83 FOUR The Drifters FIVE The Swimmers SIX The Sea Floor SEVEN Residents and Visitors DEDICATION The Oregon Oceanbook is dedicated to the many marine scientists who, over the years, have worked to gather, record, and interpret clues to the mysteries of the ocean. Without their work, this book would not be possible. The Oceanbook is also dedicated to the people of Oregon, and elsewhere, whose tax dollars supported this marine research and the preparation of this book. In this sense, the Oceanbook is a return on that investment. I WHY WE WROTE THE BOOK ABOUT MEASUREMENTS ntil now, no available publication has integrated fundamental ne of the more difficult decisions in preparing the Oceanbook oceanographic concepts with basic research from the Pacific was whether to use metric or English units of measure. We Ocean off the coast of Oregon. Researchers have written chose to use metric units because virtually all scientific hundreds of scientific papers on numerous aspects of sampling uses this system. However, we have included units Oregon's ocean representing countless hours of field work, but to most in the more familiar English system where we felt clarification would aid of us, such papers are neither readily accessible nor easily understood. understanding. Those who wish to convert from metric to English units Likewise, a number of good introductory textbooks on marine science are referred to the conversion table of weights and measures in the are available, but they lack specific information for the Oregon region. Appendix. The Oceanbook brings together both basic oceanography and research data to describe and characterize Oregon's ocean for the interested A FINAL WORD public. reparation of the Oceanbook has enriched our understanding of SCOPE OF THE BOOK the ocean's complexity and has impressed upon us that we are indeed part of a web of life that begins in the ocean. Assem- he Oceanbook focuses on the ocean environment from the bling and condensing the volumes of information, we have coastline to roughly 200 miles offshore, the limit of U.S. jurisdic- come to appreciate the detail in which the ocean has been studied. tion, and from Cape Mendocino, California, to Vancouver Island, Although we have been unable to include all of this fascinating material, British Columbia. We excluded the intertidal area of interest to we hope that the Oceanbook will be beneficial as well as enjoyable. low-tide beachcombers from the Oceanbook because this area is well 11 Oregonians are affected by the Pacific Ocean. Our land- covered in other publications. scape, whether that of eastern or western Oregon, is a legacy We have organized the Oceanbook to reflect the structure of the marine of its relentless forces. The mild, wet weather which nurtures ecosystem. After a brief introduction to Oregon's marine ecology, we our rich valleys and forested mountain slopes is generated far include a discussion of the physical setting within which all marine life at sea. We live by the ocean or we visit often. We delight in a walk on a exists. These living marine resources vary from small and simple floating sandy beach; the sight and sound of churning surf refresh our spirits. We plants to increasingly large and more complex animals which swim freely pause on a high headland for a sweeping view of the ocean and perhaps, through the ocean. We conclude with birds and mammals, many of beneath the curve of the horizon, a glimpse of the spout of a whale. which depart the sea to the shore for a portion of their lives. Visitors tell us how fortunate we are to live here. We agree. Virtually all topics of the Oceanbook beg for expansion, and so we have Yet, for all that we enjoy and find familiar in the ocean, it remains for most attempted to exercise care in deciding what to include and what to leave _7 of us a mystery. Beneath its wave-tossed surface is a world we do not out. Moreover, there is much important information yet to be gathered to know. Beyond the horizon is more ocean, deeper and different from the improve understanding, To try to satisfy the unending need to know,.the green water that surges in white foam skirts against the dark rocks of the Oceanbook includes further references on particular topics at the end of coast. And although crabs and salmon, seals and gulls are well-known each chapter. representatives of the life which moves within this watery environment, plankton are only vaguely familiar. SOURCES More than a visual backdrop, the ocean has been a traditional part of life n writing the Oceanbook we drew from a wide variety of sources, for Oregonians. Whether by frail sailing ships, bringing settlers and including technical journals, science magazines, and textbooks. In supplies to an emerging Oregon Territory, or by huge, modern ships, addition, publications similar to the Oceanbook but covering the carrying tons of wood chips to the Far East, the ocean has been used for adjacent regions of British Columbia, Puget Sound, and California transportation. Fishermen, setting hooks and casting nets, have har- provided useful information. Of most importance, perhaps, were the vested from the teeming fish stocks not far offshore and brought this invaluable contributions of many individuals-scientists, resource man- catch ashore at numerous ports along our coast. agers, and scholars-who cast a critical eye over the manuscript, added Society's increasing demand for energy, minerals, and food, coupled up-to-date data, and provided much-needed encouragement. with growing technological capability, means that these traditional uses of Oregon's ocean may be joined by new ones. Several of them, chiefly petroleum and mineral extraction, have the potential to adversely affect the ocean and coastal environment. In turn, our increasing sensitivity to potential consequences of ocean development has created a need to better understand the ocean, its capabilities, and its limitations. Oregonians have long been concerned with the protection of ocean resources. This concern is reflected in Oregon's land-use program as Goal 19, Ocean Resources. This goal gives priority to protection and use Figure 1: Oregon's Ocean in Perspective of long-term renewable resources over the extraction and use of This drawing of a satellite view of the Pacific Ocean places the nonrenewable resources. The Ocean Resources goal requires that Oregon ocean into regional perspective. The small, shaded rec- development of ocean resources be based on scientific information and tangular area on the east side of the Pacific Ocean is the same area understanding of the impacts of proposed actions. shown enlarged on the map in Chapter Two, "Geology: the Rocks. CHAPTER ONE MARINE ECOLOGY Life and The Environment INTRODUCTION and varied realm of marine life. In this undersea world, no eneath the wave-tossed surface of Oregon's ocean lies arich organism exists in isolation; each is linked to others and to the physical elements of the sea through complex interactions. Though the details of these interactions vary from place to place within 4> AAC44OVISS W the ocean, the interactions of all organisms in all natural settings have two consequences: first, a flow of energy from autotrophs, plants which A-;4_RD >,Zt, make their own food through photosynthesis, to heterotrophs, animals which are unable to manufacture their own food and must rely on 543 -ic:;6 -QC:;d autotrophs or heterotrophs; second, a cycle of inorganic materials from _Z!V3 the nonliving environment through the bodies of living creatures and back again. Such a combination of living and nonliving elements through which energy flows and materials recycle is known as an ecosystem. Marine ecosystems are biologically complex and respond to many .ru" IS physical variations in the environment. Daily and seasonal changes in sunlight filtering through the top layers of the ocean surface determine W"ITIM& the input of energy to the ecosystem. Weather patterns, changeable with the seasons, affect ocean production in two major ways. Winter rainfall and spring snowmelt erode continental soils, carrying inorganic nutrients into coastal streams and the Columbia River, which then NV-4, N discharge into the coastal ocean. Summer winds produce upwelling VIMCfr34-k conditions which bring nutrients to the surface at a time when light and .7.7.......-..... I_---. temperature are most advantageous for growth. Other physical factors, Figure 2. Di .versity of Ocean Life including water depth, distance from shore, and the nature of sediments on the ocean bottom, further influence variations in marine life. This generalized diagram of marine life in Oregon's ocean shows the basic plant and animal groups and habitats. Plants growing within the lighted surface waters of the In turn, the life processes of marine plants and animals can influence the ocean are the ultimate source of food for most marine physical properties of the sea. The concentration of dissolved gases, organisms. These plants, called phytoplankton, are grazed such as oxygen and carbon dioxide, is determined in large part by the upon by a variety of small drifting animals called zoo- metabolism of microscopic plants near the ocean's suface. This essen- plankton. Zopplanktonic herbivores are in turn prey for tial biologic activity of plants removes nutrients from the water and small fish and filter-feeding whales. Organic detritus (debris) continually falls from surface waters to the sea- incorporates them into living tissue. Nutrients are then returned to the floor, providing food to benthic animals. The eventual environment as organisms die and decay. Thus, the marine ecosystem is metabolism of organic material by animals and bacteria in a product of the interaction between marine plants and animals and their the water column and on the seafloor releases inorganic environment (see Figure 2). nutrients back into the seawater. These nutrients return to .4T"-c- the surface through the process of upwelling. 4--cln, MOTMISS Although the sea is a watery environment, requirements for life in the sea are the same as those on land: energy, living space, and the chemical building blocks needed for growth and reproduction. And as with life on Marine groups shown in this figure: Habitats shown in this figure: land, plants and animals in the sea vary greatly in size. The range in size Phytoplankton: small free-floating plants (primary Pelagic: ocean environment and the animals that live there, of marine life is impressive: from microscopic one-celled plants and producers-first trophic /evel) i.e., plankton and nekton bacteria to the great blue whale, perhaps the largest animal ever to live Zooplankton: small, free-floating animals (mainly Epipelagic: upper 200 meters on earth. Equally impressive is the wide variety of form and function herbivores-second trophic level) Mesopelagic: between 200 and 1,000 meters which enables marine organisms to occupy diverse niches in the ocean Nekton: organisms large enough to effectively swim against Bathypelagic: between 1,000 and 4,000 meters currents, i.e., fish, squid, mammals, and birds (typically Neritic: the environment over the. continental shelf, also environment. carnivores-higher trophic levels) referred to as open ocean Benthic: bottom-dwelling animals and plants (a// trophic Oceanic: the environment beyond the continental shelf, also Light, temperature, salinity, bottom sediments, and other characteristics levels) referred to as open ocean of the ocean vary from one location to another. Unique combinations of Benthic: bottom sediments and the overlying portion of water these conditions create specific environmental opportunities known as within 1 meter of the bottom habitat. Within any particular habitat is a community of organisms well- suited to exploit the food and shelter there. 7 CLASSIFICATION OF MARINE LIFE ne way oceanographers classify marine life is by the habitat in r". :@@ @,z'-7@ , MI-e- Figure 3. Pelagic Food Web for Coastal Waters off which an organism lives. The two broadest categories of habitat are the pelagic (water-dwel ling) environment and Oregon A benthic (bottom-dwelling) environment. The pelagic region, A representative food web for a number of pelagic species off the Oregon coast. This food web has been simplified from data where most marine life exists, is divided horizontally into a neritic collected during the summers of 1981 and 1982 by the Oregon province, from shore to the edge of the continental shelf, and an oceanic State University Early Life History of Salmon Project (1981-83). The province beyond the shelf break (see Figure 2). The pelagic region is also web shows how food energy enters the marine ecosystem through categorized vertically into an upper, euphotic layer, where there is phytoplankton at the lowest trophic /eve/ and is accumulated into sufficient light for plant growth (usually greater than one percent of the increasingly large and more complex organisms at higher trophic incoming solar radiation), and a lower, aphotic layer where there is not. levels. Drawings are not to scale. The boundary between these two layers varies daily and seasonally according to the angle of the sun's incoming rays and to the amount of turbidity in the water. In the turbid and highly productive waters of the midshelf off Oregon, light may penetrate to 30 meters (though it varies 14 from 15 to 35 meters, depending on location over the shelf) and to 60 meters in the less productive, less turbid waters over the continental slope (5). Pelagic Environment Ithough pelagic organisms exhibit a variety of life modes, /o _!F11 scientists group them into two broad categories. Drifters are @K@ @ termed plankton and active swimmers are called nekton. -41@ Drifting plankton may be either plants or animals. Plankton vary in size from ultraminute bacteria to large jellyfish. They live in the IN@HORZ (APPWX, 5,1111) @I*@MRZAIYXMIY euphotic zone as free-floaters unable to move faster than the speed of the current. Nekton include invertebrates (animals without backbones) and vertebrates (animals with backbones) such as fish, seabirds, and locations. The limitations are not necessarily physiological. They can be In the unconsolidated sediments, infauna, such as worms and clams, mammals. Because of their ability to swim, they range throughout the environmental boundaries such as changes in temperature, salt content, burrow or otherwise live below the surface. These organisms are depths of the ocean. oxygen, and nutrients. important in reworking the soft sediments, mixing deposits of mud and Phytoplankton are microscopic, free-floating plants which provide the Off Oregon, the nekton include two important groups, the invertebrate sand into combinations of the two. Epifauna, such as starfish, crabs, and nutritional base for most of the sea's vast array of life (see "Plankton: the squids and the vertebrate fish. As a group, the fish nekton make a major sponges, live on the surface of all bottom material. Most of the ocean Drifters"). They are the most numerous of all organisms in the ocean. contribution to Oregon's recreational and commercial fish catches, both bottom lies in total darkness. Only in the ocean's thin surface layer is Unlike higher plant life, which can contain billions of cells, each phy- in pounds landed and in dollar value. sunlight sufficient for the synthesis of organic material that fuels and toplankton, such as a diatom, consists of only a single cell. Though the Marine mammals and sea birds are often included in the nekton category builds life in the sea. Thus, benthic animals are dependent upon a "rain" cells are sometimes linked together to form chains, each individual cell is since both spend all or much of their lives at sea (see "Marine Birds and of dead or decaying plant and animal material falling from above as a self-sufficient; the chains are colonies, not organisms. Mammals: Residents and Visitors"). But some marine mammals, like source of food. (Animals living around deep-sea hydrothermal vents are Zooplankton, planktonic animals, include many major animal groups (see seals and sea lions, must come ashore to give birth. Others, like the an exception to this generalization. This community derives its energy "Plankton: the Drifters"). Zooplankton convert plant material to animal great whales, reproduce in the ocean. Sea birds also use terrestrial sites from the vent fluids rather than from the sun.) Food items reaching the tissue and are a crucial food for larger animals. The young of many for nesting and breeding. Both groups have evolved a diversity of body benthos are varied; they include organic material absorbed in tiny species, such as fish, exist as zooplankton until they grow large enough shapes and feeding apparatus to pursue and capture their prey. Most of sediment particles and an occasional large carcass of a whale or fish. to swim independently or until, as is true for clams, they emerge as the adult species of this group are ultimate consumers in the marine adults living on the bottom. Organisms that remain plankton all their environment. TROPHIC STRUCTURE lives, copepods for instance, are known as holoplankton; animals that he marine ecosystem, like all biological systems, is driven by are planktonic temporarily, such as most fish species, are called Benthic Environment energy. Energy moves through the ecosystem along trophic macroplankton. The planktonic phase of an organism's life history allows enthic organisms are the bottom-dwelling plants and animals pathways-the means by which more complex organisms of for widespread dispersal to suitable environments by ocean currents. of the ocean (see "Benthos: the Seaffloor"). They exhibit a higher trophic levels obtain nutrition from simpler organisms of Many zooplankton are restricted to the surface euphotic zone since they variety of different life modes-. sessile (attached to the bottom), lower trophic levels. live by grazing on light-dependent phytoplankton. However, some can burrowing, and creeping. The distinction between a pelagic In the first trophic level, plants convert the sun's energy into simple swim. Many groups of zooplankton, including copepods and euphau- and a benthic existence is not always clear since some adult demersal inorganic elements (carbon, hydrogen, oxygen, and nitrogen) dissolved siids, migrate from 100 to 200 meters to the surface at night and move organisms (nekton living on or near the sea bottom), such as shrimp and in the sea into energy-rich, complex, organic compounds which the back down during the day. rattail fish, regularly move from the seafloor into the water column for plants use to carry out their life processes. In the second trophic level, Nekton are a diverse group of free-swimming animals, both with and food. The benthic habitat is extremely diverse with a variety of niches on herbivores (plant-eating animals) consume this flourishing plant biomass without backbones, which range throughout the pelagic zone (see the seafloor. There, different habitat opportunities abound, ranging from to sustain their life functions. In the third trophic level, other animals "Nekton: the Swimmers"). Although nekton generally are widely dis- hard, exposed rock to soft, unconsolidated sediment. Variations in consume the herbivores. This consumption of a lower trophic level by a persed, some nekton are restricted to certain depths or geographical particle size and organic content of the soft sediments create a organisms at a higher, more complex level continues up the trophic multitude of different sites for specialized benthic development. ladder until the highest order of carnivores, organisms that consume no UO MAMIE [ECOLO&Y A .4, 00"i2ZA, "" R, F, flesh, is reached. Detrivores, animals that take advantage of waste in the A Mo, system, eat particles of decaying plant or animal matter not consumed - -a" , by herbivores or carnivores. A trophic pathway is not a single chain of linear interactions, but a web of several interlocking feeding sequences (see Figure 3). In practice it is difficult to categorize species according to trophic level. Some species are ominivores, feeding on several different trophic levels during a single N, N '14 N! life stage. For example, the northern anchovy feed on both phy -@iq toplankton and zooplankton. Trophic position can also change through- out the life cycle of an animal: larval fish may feed on phytoplankton, but juvenile fish of the same species probably consume zooplankton. Some prey upon species belonging in their own trophic level. For example, starfish larvae are preyed upon by other zooplankton, including certain larval stages of the shorecrab. Figure 4. Electron Micrographs Reveal Microscopic Hunter and Prey No energy transformation is 100 percent efficient. Energy is lost at each These photographs, taken with an electron microscope, provide marine scientists with a look at the microscopic world of hunter transition between trophic levels. For instance, in areas of coastal and prey. At left, a surf smelt larvae (approximately 100 days old) has attempted to eat a crab zoea. The long dorsal spine of the upwelling, of the total amount of energy captured by plants, approx- zoea has pierced the upper lip of the surf smelt larvaejust below its developing nostril. The eye of the smelt larvae is the large imately 15 percent shows up as increased growth and reproduction of round feature at the left of the photograph behind the tip of the protruding spine (55x). At right, the microscope dramatically herbivores. Only about 15 percent of the energy consumed in herbivores magnifies hunter and prey approxi .mately 600 times life size. A larval hermit crab has captured a tiny copepod. Had the larval emerges as new growth and reproduction in primary carnivores, and so hermit crab not been captured by scientists, it too may have become prey for a larger animal. (Electron micrographs by Carla on (4). Energy not used for new growth and reproduction is lost from the Stehr, NMFS, NOAA.) ecosystem in a variety of ways: as unassimilated food matter (fecal pellets) which sinks to the seafloor; as metabolic processes, such as important, but little is known about them. Some of the cletrital material three times that farther offshore (4), also means that a greater abun- respiration, which releases energy as waste products; and as non- reaches the seafloor where it becomes a source of food for scavengers dance of animals can be maintained over the continental shelf than in predatory mortality. Such energy losses lead to a decrease in the and other bottom-dwelling creatures. deeper water. number of individuals in successively higher trophic levels that can be supported by the trophic level below. Dissolved organic material, a much greater proportion of the organic There are usually fewer trophic levels in the nearshore than in the open soup, is produced during animal metabolism. Zooplankton and fish can ocean environment. In the high-nutrient, turbulent environment of the NUTRIENT CYCLING excrete highly concentrated organic elements which are of direct use by coastal region, phytoplankton cells tend to be large or form colonies of marine plants and bacteria. several individual cells which are in turn eaten by large herbivores. These hereas energy flows from one trophic level to the next, being large herbivores serve as prey for large carnivorous fish such as salmon. converted to organic matter in ever-decreasing quantities, As plants grow, they continually remove nutrients from the surrounding inorganic nutrients recycle through the marine ecosystem. water. To sustain growth, nutrients must be resupplied to the surface In contrast, the low-nutrient input of the stable, open-ocean environment Many simple inorganic elements, the building blocks of a waters. Since detrital particles sink, nutrients are released back into the tends to favor the growth of much smaller phytoplankton. Furthermore, biological superstructure, abound in the sea. Some elements, however, ocean beyond the reach of the plants which need them. Several herbivores are usually smaller, although large herbivores like the filter- are available in marginal quantities, and their scarceness could become mechanisms for replenishing the surface waters with nutrients are at feeding whales often feed in these waters. Several more trophic levels a limiting factor to the growth of marine plants. This is particularly true of work off the Oregon coast, including wind mixing, upwelling, and coastal might be required before prey items reach suff icient size for larger fish to nitrogen off the Oregon coast. runoff (see "Oceanography: the Water"). effectively forage for food. Thus, the larger the plant cells at the bottom of the food chain, the fewer the trophic levels required to convert the Nutrients are taken up by phytoplankton at the surface during photo- CONTRASTING THE COASTAL AND OCEANIC organic matter to a useful form (4). synthesis and incorporated into organic compounds (proteins), first in The number of trophic levels present can have important consequences. plants and then in animal tissue. Plant nutrients not converted into ECOSYSTEM The yield of large commercial fish species may be increased when there animal tissue are returned to seawater as both particulate and dissolved everal important differences exist between Oregon's continen- are fewer trophic links. In other words, the sun's energy is converted organic matter. tal shelf ecosystem and that of the deepwater oceanic region. more efficiently into large fish when there are few trophic levels because Particulates, known collectively as detritus, include uneaten food, fecal On average, because of coastal runoff and updwelling, the flux of the great reduction in energy conversion with each succeeding pellets, and plant and animal fragments. Marine bacteria decompose of nutrients into surface waters is greater over the shelf than trophic step. This increased yield in the coastal zone, coupled with the these particles as they slowly sink to the ocean bottom. Thus, the that into surface waters of the deep sea. Therefore, plant production is economic hardship of fishing far out to sea, explains why most commer- bacteria return inorganic elements to the ocean in a form again usable by higher over the shelf than it is in the deeper waters beyond. The large cial fisheries are located near the coast (3). plants. Other organisms, such as single-celled animals, may also be quantity of phytoplankton produced in coastal regions, approximately nQ X&RDHE ECOLCOW @&J REFERENCES Note: References are cited in text by number. References marked with an asterisk (*) are recommended because they are comprehensive, easily understood and/or accessible. 1 .Brodeur, R. D., W. G. Pearcy, and H. V. Lorz. 1984. Trophic Interactions Among Juvenile Salmonids and Other Pelagic Nekton in Coastal Waters Off Oregon and Washington. College of Oceanography, Oregon State University, Corvallis, Oregon. (Unpublished data.) 2. *Isaacs, J. D. 1969. The Nature of Oceanic Life. In Readings from Scientific American- Ocean Science. W. H. Freeman and Company. 3. Landry, M. R. 1977. A Review of Important Concepts in the Trophic Organization of Pelagic Ecosystems. Helgrol. wiss. Meerewaters 30: 8-17. 4. Ryther, J. H. 1969. Photosynthesis and Fish Production in the Sea. Science 166:72-76. 5. Small, Larry. 1985. Personal Communication. College of Oceanography, Oregon State University, Corvallis, Oregon. 6. *Strickland, R. M. 1983. The Fertile Fjord. Washington Sea Grant, University of Washington, SeaWe, Washington. Additional References *Cushing, D. H. and J. J. Walsh, editors. 1976. The Ecology of the Seas. W. B. Saunders Co., Philadelphia, Pennsylvania. *Levinton, J. S. 1982. Marine Ecology. Prentice-Hall, Englewood Cliffs, New Jersey. *Nybakken, J. W. 1982, Marine Biology-An Ecological Approach. Harper & Row, New York, New York. *Parsons, T. R., M. Takahashi, and B. Hargrave. 1977. Biological Oceanographic Pro- cesses. Pergamon Press, Oxford, England. X&ROKE ECOL&MV CHAPTER TWO GEOLOGY The Rocks INTRODUCTION PLATE TECTONICS - A REVOLUTION The movement and interaction of these plates is called plate tectonics. The spectacular Oregon coastline of today is the result of EARTH SCIENCE Seven major plates and several minor plates have been identified (see geological and oceanographic processes, some of which have ne of the most significant ideas to emerge in the earth Figure 6). Two hundred million years ago the positions of the continents occurred over a long period of time and on a vast scale. The sciences began to take shape during the 1600s when geog- and the shape of the ocean basins that lay between them were slow, relentless movements of the earth's crust or the gradual raphers observed that the coastlines on either side of the significantly different than they are today. Similarly, 50 million years from rise and fall of sea level are neither seen nor felt but nonetheless play a Atlantic were a remarkably good fit. Perhaps, it was thought, now, these relationships will again be quite different. For instance, Baja fundamental role in creating the unique features and resources of the the two continents had been joined together at some time in the past. California will move north to a position off the west coast of the United Oregon coast. Other forces act on a daily or seasonal basis and result in Biological evidence began to accumulate in the late nineteenth and early States, and the Pacific Ocean basin will be much smaller than it is today. changes that are evident in a short time. Wind and rain, rivers and surf, twentieth centuries to support this hypothesis of continental connection. Thus, any map of the present position of the continents is only a summer sun and winter storms all continue to refine, remake, and rework It was not until the 1960s, however, that geological evidence gathered snapshot. coastal features. through more sophisticated measuring and mapping techniques con- Although some 400 miles long, the Oregon coast is but a very short firmed that the dynamic interactions which occur between the earth's segment of the Pacific coast of North America. Thus, many of the factors inner and outer layers provide a possible explanation for the lateral and affecting the development of Oregon's coastline must be seen in the vertical motions of the earth's surface (18). larger context of the development of the present Pacific coastline and of This new evidence revealed that the earth's surface is merely a skin of the formation of all of the Earth's continents. crustal material lying upon thin, rigid blocks embedded in the This chapter of the Oceanbook first introduces plate tectonics, the lithosphere, the layer from which the blocks are made. These blocks or theory that explains the slow, massive shift in continental and oceanic plates "float" upon the asthenosphere, a hot, soft, subsurface layer of outlines over time and how this shift has formed the Pacific Northwest. the earth. Deep, internal heat currents, generated by radioactive decay, The chapter also reports an exciting discovery and the pioneering drive the blocks slowly across the face of the earth. Below the research taking place deep on the ocean bottom off the Oregon coast. asthenosphere, semimolten material is layered around what is thought to Finally, it takes a look at the features and processes of Oregon's be a solid inner core (see Figure 5). nearshore ocean, with comments on economically valuable resources of Oregon's offshore geologic environment. TECTONICS OF THE PACIFIC NORTHWEST The tectonic history of the Pacific Northwest provides a good example of the changing relationships between the earth's plates. The plates now found off the Oregon coast have not always been in their present locations, nor have their boundaries always been what they are today. Over the past 30 million years, the Farallon Plate, one of four ancient Pacific Ocean plates, has gradually disappeared under the westward-moving North American Plate. The Juan de Fuca is a remnant of this plate. The once-continuous ocean ridge which connected the Gorda and Juan de Fuca ridges to teh East Pacific Rise far to the south off Central America has been consumed in the ocean trenches that once lay offshore Califronia and has since been replaced by the San Andreas transform fault(26). Figure 7. Movement of Plates Affectin Oregon The Juan de Fuca Plate is subtractin beneath the North American Oregon lies at the junction of many complex plate interactions (see Figure 7). Offshore, the floor of the Pacific Ocean consists of the Pacific Plate, moving northwest, and the Juan de Fuca Plate, moving northeast. Plate. The Explorer Plate and Gorda South Plate fragments, which These two plates diverge along the Juan de Fuca and Gorda ridges. have decoupled from the motion of the Juan de Fuca Plate, are The Juan de FUca Plate, in turn, is converging with the North American Plate at the coastline and is being subducted; that is, one plate is being pulled under another. increasingly infuenced by the motion of the Paicfic Plate and are In addition, parts of the Juan de Fuca Plate are sliding past the Pacific Plate along transform faults, known as teh Mendocino, Blanco, and Sovanco fracture zones. resisting subduction under the North American Plate. Arrows show the relative motion of the plates. It appears, too, that the remainder of the Juan de Fuca Plate is itself in the process of breaking up into small plate fragments(33). The movement of the Juan de Fuuca Plate no longer dominates the Explorer Plate fragment off Vancouver Island or the Gorda South Plate off northern California. Their motion seems to be more strongly influenced by the pull of the adjacent Pacific Plate as it moves slowly to the northwest. Both the Gorda and Juan de Fuca ridges are elevated submarine This motion, along with the buoyancy of hte fragments and their decoupling from the downward pull of the Juan de Fuca Plate, appears to be causing these microplates to pivot slowly as they resist subduction under North America(33). features. Hot new volcanic material wellin up beneath them is less dense and more buoyant than the colder, older crustal material away OCEAN RIDGES from the ridge. They have a central or "axial" valley along the length of Some 200 to400 kilometers off the coast of California, Oregon, and Washington lie the Juan de Fuca and Gorda ridges(see figure 7). These midocean ridges form part of a global network of ridges nearly 60,000 kilometers long, linking the major ocean basins of the world(13). the ridge crest, usually several kilometers wide and of rugged topogra- The Gorda Ridge, located within 200 kilometers of the Oregon coast off Cape Blanco, is one of the ridge segments closest to the continental United States. phy caused by faulting and uplifting. Within the axial valley, mounds of smooth lava flows, toothpastelike, rounded pillow lava formations, and The geological processes at the Juan de Fuca and Gorda ridges result in the formation of new oceanic crust and in volcanic activity. chimneylike structures indicate volcanic activity (18). As the plates move away from the ridge, pressure on the underlying volcanic material is relieved and hot volcanic magm from the mantle wells upward into a magma chamber underneath the crest of the ridge (see Figure 9). Liquid rock, chiefly basalt, in the upper layers of this chamber makes its way to the surface through vertical passageways and erupts on the ocean floor (13). The Gorda Ridge is approximately 300 kilometers long and consists of Other molten material remains trapped in the vertical cracks to hardens, and becomes part of the plate. three segments. The axial valley of the Gorda Ridge is quite deep, ranging from 3,200 meters in the south to 3,800 meters in the north. The Once added to the plate, the now hardened basalt material is transported away from the ridge. valley is also wide, from several to nearly 19 kilometers. Within this valley, The rock continues to cool and contract, forming cracks and crevices. vertical relief ranges from 800 to 1,400 meters. Many small, concial The plates are drivern away from the ridges by convection currents generated by heat within the rocks of the upper mantle of the earth and by gravity as the plates slowly slide off the elevated ridge. seamounts, probably submarine vocanoes, lie adjacent to the ridge axis; all but the larger ones to the east of the axis are buried beneath 14 GEOLOGY sediments(7). The 500-kilometer-long Juan de Fuca Ridge, north of the Gorda Ridge, is offset to the west by the Blanco Fracture Zone. The depth of the axial valley is 2,000 to 2,600 meters, although where the ridge intersects with the Cobb Seamount it comes to within 1,500 meters of the surface (the surface). This is signifiantly shallower than the Gorda Ridge. The axial valley of the Juan de Fuca Ridge is more V-shaped than that of the Gorda Ridge and onley 1 to 2 kilometers wide(5). The ridges form a topographic barrier fo sedimnet movement from the nearby continent. The northern portion of the Gorda Ridge is narrow, deep, and rugged (7); but the southern third of the Gorda Ridge,known as the Escanaba Trough, is filled with sediments derived from both the Columbia River and the Klamath Mountain drainages. These sediments appear to have been transported through the Blanco Gap (sometimes called the Blanco Saddle) and around the south end of the ridge before settling out the Escanaba Trough(23). The reverse appears to be true for the Jaun de Fuca Ridge; its southern half is rugged whereas a thick blanket of sediments covers the northern segment. Full spreading rats(the total amount of crustal formation at a spreading center) vary along the two ridges. The full spreading rate on the northern end of the Gorda Rige is approximately 5.5 centimeters (slightly more than two inches) per year but only 2.3 centimeters per year on the southern end, more typical of slow-sprreading centers like the Mid- Atlantic Ridge. Total spreading rates for the Juan de Fuca Ridge, on the other hand, are somewhat faster and range from 4 centimeters per year in the south to 10 centimeters per year in the north (7). Figure 8. Seafloor Spreading off the Oregon Coast This diagram, which is not to scale, shows the relative movement of the Pacific and Juan de Fuca plates away from the Juan de Fuca Ridge. The Juan de Fuca Plate is being forced down under the overriding North American Plate; this process is called subduction. 133* so- 132' 125* 124* 123' 122' 121* 49- 4W 47- 46- 6 is 0 BASIN z 44- 4 'L.A 0IN Will 42- ip m 41- 'ORD B A 40- 133- 13 129- 128' 127' 126, 125' 124* 123' 122' The differences in the spreading rates along the Gorda and Juan de Fuca ridges result from the varying directions of motion of several plate segments (see Figure 7). The subduction trench lies relatively close to the ocean ridge system where plate material is generated, but the younger, more buoyant plate material resists subduction and is increasingly influenced by the motion of the Pacific Plate sliding north- west. The Juan de Fuca, Gorda South, and Explorer plate segments exhibit varying degrees of clockwise pivoting motion as they are consumed under the continent, The Juan de Fuca Plate system appears to be an example of the final stages in the plate tectonic process, where small plate fragments become dominated by the motion of larger, bordering plates (33). Subduction Zone From Cape Mendocino to Vancouver Island, the Juan de Fuca Plate and the North American Plate converge to create a zone of very active geologic forces. As the Juan de Fuca has been IF thrust under the North American Plate, sediments riding on the oceanic crust have been scraped off and added to the edge of the continent in complex geologic structures. This convergence has also resulted in the uplift of the entire continental margin, including the Coast Range, the Cascade Mountains, and perhaps even the Blue Mountains of northeastern Oregon (10). Finally, eruption of the Cascade volcanoes is the result of the partial melting of this oceanic plate as it slides under the earth's upper layers and re-emerges as volcanic material on the continent. Although subduction zones are usually characterized by earthquake activity, the Oregon coast is unique because there is a notable yet unexplained-absence of earthquakes (10). One possible explana- tion is that the still-warm, relatively young Juan de Fuca Plate is slowly bending, like taffy, rather than breaking and releasing earthquake energy. Another explanation is that sediments, riding on the down-going plate, have a lubricating effect between the two plates. Transform Faults The Juan de Fuca and Pacific plates slide past each other along the transform faults of the Blanco Fracture Zone and the Mendocino Fracture Zone. Likewise, the North American Plate and the Pacific Plate slide past each other along the San Andreas Fault. Considerable earthquake activity and geologic uplift Figure 9. Cross Section of An Axial Valley occur along the Blanco and Mendocino fracture zones, as evidenced by Magma (molten rock) rises beneath an ocean ridge, a zone of plate sep the rugged undersea mountains. Because these rock layers are not well through a network of cracks in the rocky ocean floor, is heated by magm lubricated, resistance between the rocks on either side of the plate mineral-rich water is ejected into cold seawater at hydrothermal vents. boundary builds up tremendous strain. When a threshold level of stress adds new basalt to the oceanic crust. is reached, the rocks give way and energy is released as an earthquake. MIDOCEAN RIDGES AND HYDROTHERMAL VENTS ince World War 11 scientists have used remote sensing tech- ti hydrothermal vents provide an environment for remark- c ive xxb d... .... ..... . ............ niques such as magnetometers and acoustic reflection to .......... . .. ....... able biological communities on the deep ocean floor. Instead of sketch a picture of the shape and structure of the ocean using sunlight and photosynthesis to sustain life, the food . ..... ..... ..... ... ...... . ............. .. ........... XXX ...... ...... .... .. ............ .. bottom. However, direct exploration of deep miclocean ridges chain thrives on chemosynthesis, that is, the metabolism of ................... . ........ ... .......... with submersible research vessels has been possible only in the last two ..... . .. .... ..... .. ....... ... hydrogen sulfide ejected from the hot springs. Bacteria use the hydro- .......... X decades. The Mid-Atlantic Ridge was the first area to be directly gen sulfide for energy to incorporate carbon, oxygen, and hydrogen- observed. The ridges off Oregon have been directly observed only since X X.X@::X the building blocks of life-into organic tissue (16). . ..................... *_ ............... ...... .. .. . ............ .......... 1979. sw ...... . . . ... X.1.411X. In 1977, 320 kilometers northeast of the Galapagos Islands, 0@1 These bacteria are abundant and very productive even at the incredibly high temperatures found at 21 N and the enormous pressure at depths ... .......... .... .. oceanographers John B. Corliss of Oregon State University and John M. ..................... d. UAN C6 AreA of 2,000 to 3,000 meters. The bacteria that live on the sulfur are 2 to 4 ............ ... Edmond of the Massachusetts Institute of Technology became the first times as productive as surface bacteria and 100 to 1,000 times more to witness the hot springs of a midocean ridge. Geologists had sus- ................. productive than seafloor communities away from vent sites (16). When pected that such activity, analogous to geysers and hot springs on land, might exist on the ocean floor. Although the geological discovery may Ralf e s. a A lights are shined through the water issuing from the vents, it appears faintly milky and bluish from the concentrations of bacteria and sulfides. have been anticipated, the biological one took the scientific community 5AN AND9,F.M;, FAULIT .. ... ....... The bacteria are ubiquitous: in the vent fluids, on all surfaces, in the . . ............- by surprise. Nearly three kilometers below the surface of the Pacific .......... water column above the vents, and within organisms. Ocean was a community of worms, crabs, and fish clustered around the ............ ............ .. hot springs thriving on the chemically rich vent fluids as a food source A host of creatures either feed directly on the bacteria or rely indirectly ............ totally independent of the sun. on the bacteria to provide their nutrition. Mussels and clams, some over 30 centimeters long, extract bacteria from the water. The magnificent Scientists have begun to understand how such hot, super-saturated (Z/ N) fluids are generated within the earth and how this process effects the mouthless tube worms, up to two meters long, feed by absorbing EA-157- dissolved nutrients created by bacteria living within their bodies. Many chemical balance of the ocean, deposits metal-rich sediments on the (12-ON ............ seafloor, and creates an environment for a unique biological community new families and subfamilies of marine worms, clams, crabs, and in the deep ocean (40; 16; 1). ..... ................. .. .. .. ......... ............ .......... ........ ..... ..... .. barnacles have been found in these spectacular oases of abundant life in an otherwise deep ocean desert (14). As the newly emerged ocean crust moves away from the spreading ............ ridge, it cools and cracks. Cold seawater seeps into these cracks, draws heat from the molten rock, and rises to the surface through vents on the he discovery of these hydrothermal vent systems and their ........... ridge crest. As the water circulates it leaches iron, zinc, copper, nickel, FAI@T' PAOFLI- P11156 circulating sea water may also have given scientists a keener and other metals out of the rock. These heavy-metal molecules combine understanding of the chemistry of the ocean. It is estimated that with sulfide, a compound of sulfur and oxygen, and remain in solution U-St6lb- X... on a global scale hydrothermal vent systems circulate approx- under the tremendous pressures and temperature of the vent network. imately 6,000 cubic meters of water per second (about one-third the Wheri this hydrothermal solution erupts into the cold, deep ocean, the annual flow rate of the Mississippi River) (39). At this rate, the entire sulfide compounds precipitate out as polymetallic sulfides, forming Figure 10. Juan de Fuca System and East Pacific volume of the ocean could circulate through the worldwide midocean chimneys, spires, and metal-rich sediments (see Figure 9). Rise ridge system in about 8 million years (11). And in the process, minerals wo kinds of vent systems have been found. The type of mineral Spreading centers along the East Pacific Rise have very active contained in the hydrothermal fluids return to the ocean soup sub- deposited by a vent depends on the internal plumbing of the hydrothermal vents and major sulfide mineral deposits. The once- stances that have been removed in biological and chemical processes. cracks. In a "leaky" system, of which the Gorda Ridge is continuous ocean ridge system connecting the Juan de Fuca and probably an example, seawater and hydrothermal fluid mix but Gorda ridges with the East Pacific Rise has been consumed under In 1983, the U.S. government, excited by the prospect of valuable deposit the sulfide minerals below the surface within the vent system. North America and replaced with the San Andreas Fault. minerals on the ocean floor within the U.S. 200-mile Exclusive Economic The waters which are eventually returned to the ocean environment are Zone, proposed to lease an area the size of South Dakota surrounding on the order of 19' to 57' C (water boils at 100*C) (7). and including the Gorda Ridge. The leases would have been for exploration and mining of the polymetallic sulfide minerals hypothesized In a "tighter" system, such as the one at 21 0 N on the East Pacific Rise to have been formed in the sea. It was determined, however, that too (see Figure 10), the minerals remain in the superheated solution until little was known about the Gorda Ridge to proceed with a lease. But the they reach the surface. At the surface, the mineral-rich brine emerges at U.S. Geological Survey, the National Oceanic and Atmospheric Admin- 350' C through chimneylike features known as "black smokers" and istration, and other research agencies have begun a program of detailed precipitates in massive deposits. Hydrothermal systems like this one exploration of the Gorda Ridge. This program is intended to provide appear to be the origin of geologic formations that contain significant information about the geologic formation of the area, its mineral quantities of metal ore. One such formation on Cyprus has yielded resources, and the extent and kinds of biologic communities at vent copper ore for centuries (27). sites. MAJOR GEOMORPHIC FEATURES OF THE OCEAN FLOOR OFF THE PACIFIC NORTHWEST The floor of the northeastern Pacific Ocean is dominated by two major regions: a large, deep ocean basin and a relatively narrow, shallower continental margin (see map: Bathymetry: Oregon Continental Margin). These distinct regions result from the interaction of crustal plates and subsequent continental uplift, erosion and deposition, oceanographic processes, and seasonal weather pat- terns. Ocean Basins The Cascadia Basin, the deep ocean basin off the Pacific Northwest, is the sediment-covered surface of the Juan de Fuca Plate north of the Blanco Fracture Zone. A gently sloping, deep- sea plain, the Cascadia Basin ranges in depth from 2,400 meters in the north to 2,800 meters in the south (15). The southern portion of the basin is quite flat and is characterized by nearly buried seamounts, thought to be volcanic in origin, protruding through the sediment cover. The basin receives a large load of sediment from continental and Figure 12. Sediment Thrusting under the Continent nearshore sources via submarine canyons which deposit their load in Subducting oceanic crust carries a sediment load which is scraped thick deposits known as deep-sea fans. The Nitinat Fan, west of the Juan off and thrust as successive wedges under older layers at the toe of de Fuca Strait, fills the northeast portion of the basin and is composed of the continental slope. The rates and locations of uplift vary over sediments from Puget Sound and the Fraser River drainage of British time. Arrows show the relative movement of layers. Columbia. The Astoria Fan off the Columbia River fills much of the eastern portion of the basin with sediments from this great river system. One of the longest seachannels in the world, the Cascadia Channel, As the oceanic crust is subducted, the overlying sediments are scraped bisects the basin fron north to south. Originating at the base of the off the oceanic plate and added to the continental plate as wedges continental slope, the Cascadia Channel is two to four kilometers wide thrust successively one under the other (24) (see Figure 12). This and 20 to 300 meters deep. This channel system is an important avenue scraping process, termed "imbricate thrusting" by geologists, accounts for moving sediment from the continental margin to the deep ocean for the presence of older oceanic sediments found uplifted above basin beyond the Blanco Fracture Zone. Although a substantial amount younger sediments on the shelf. Rates of uplift have varied over time and of sediment has bypassed the Cascadia Basin by means of this channel, range from 100 to 1,000 meters per million years. Areas of active uplift thick layers of sediment have ponded in the southern and western may also vary along the coast; the Cape Blanco area appears to have sections against the mountains of the Juan de Fuca Ridge and the been the most active in the recent geologic past (4). This steady uplifting Blanco Francture Zone (15). and tilting of rock layers in the coastal area continues today (33). Along the eastern edge of the Cascadia Basin near the toe of the Historical changes in sea level have also influenced the nature of the continental slope is another smaller channel. The Astoria Channel carries continental margin. Extensive glaciers formed in the polar regions sediments from the lower flanks of the Astoria Fan southward to the approximately 2 million years ago and captured enough of the earth's Blanco Gap and the Gorda Basin beyond. water as ice that sea levels dropped dramatically. Since then, a number of climatic oscillations have taken place with shifts in the mean annual The Gorda Basin, lying south of Cape Blanco between the Gorda Ridge temperature between interglacial and glacial periods of 3 to 6 C in and the continental slope, is much smaller than the Cascadia Basin. Its maritime areas and 12 C in continental areas (12). The most recent southern edge is enclosed by the east-west ridges of the Mendocino glacial period ended about 10,000 years ago as glacial ice, covering the Fracture Zone. However, the Gorda Basin is deeper than the Cascadia Puget Sound area and much of the Olympic Peninsula, melted and Basin and is filled with sediments to a virtually flat 3,000 meters. These returned as water to the oceans. The continental ice sheet covering sediments have buried many of the mountains on the landward flank of parts of Puget Sound does not appear to have moved as far south as the Gorda Ridge and also filled the Escanaba Trough (23). Oregon (28). The ContinentaL Margin During the last period of lowered sea level, Oregon's shoreline was well to the west of its present location. Coastal rivers cut across the Oregon's continental margin is composed of three major fea- continental shelf to deliver sediment directly ro the deep ocean. When tures: the continental shelf, the continental slope, and sub- temperatures warmed and the ice sheets gradually melted, the pre- marine canyons dissecting both. The continental margin has viously exposed coastal plain was flooded by ever-advancing shorelines been shaped by two fundamental geologic processes: plate and covered by deposits of mud, sand, and gravel (21). The rising sea tectonics and sea level change. Plate tectonics has built Oregon's level reduced the rate of sediments delivered to the deep ocean by continental margin slowly westward over the past 60 million years creating a depositional environment over the now submerged continen- whereas sea level changes have occurred within the relatively more tal shelf. recent period of 10,000 years. 18 GEOLOGY WEI@,T_ ..... ... . z.@ A. 15&MON OFF . . . . . . . . -.......... ... . ...... VPFVUAN@ PAY .......... ...... ..... Figure 14. Seismic Survey Profile Printout ........... Rock layers underlying Oregon's continental shelf are shown in this ........... 4 computer printout of a seismic survey performed in fall 1984. The ............ C ... ........ horizontal bands at the top are over one kilometer thick and were . ........ ?,eex,_ . .... . .............................. . deposited on an erosional surface an top of folded sedimentary . ........ C -'SCY-10A/ 0Ar AA ... .. ...... ........ rocks. This cross section, which shows rock layers over 7 kilometers ... ...... . .. ............ . deep and nearly 13 kilometers wide, was taken by the RIV "Arco Resolution. (Photo courtesy of Mike Bell, ARCO Exploration.) Rocky outcrops, erosional remnants of shoreward rock formations, are ...... .. ... also found on the inner shelf, especially between Coos Bay and the Rogue River (22). Nearshore, sea stacks and other rocky islands provide ........... nesting sites for sea birds. Many of these features are part of the Oregon ......... .. Islands National Wildlife Refuge system. Figure 15. De Submergence Research Vehicle Alvin A@ter Ctl&n, IM, @',hn F-1,,, 1771 Continental Slope ike the continental shelf, Oregon's continental slope is also The DSRV "Alvin" being lifted from the water by an A-frame hoist relatively narrow, from 20 kilometers (12 miles) at Cape Blanco to installed on the stem of the mother ship "Atlantis //. " Scientific 96 kilometers (60 miles) off the Columbia River. Here the ocean equipment on board includes remotely controlled mechanical floor drops rapidly to meet the Cascadia Basin some 2,000 arms and various sampling equipment, underwater cameras, lights, a water temperature monitor, a current speed meter, and a Figure 13. Seismic Profiles of the Continental Margin meters below. pred .si.on depth indicator (photo by Rod Catanach, WHOI). Seismic surveys provide clues to the sedimentary structure beneath The upper slope is characterized by gently sloping benches and low- the seafloor. These three cross sections of the Oregon continental relief hills. Blocks of rocky material, probably hard mudstone (23), have 1984 ALVIN DIVES ON THE OREGON CON- margin show how sediments appear to have been ponded behind been rapidly uplifted by the underthrusting oceanic plate and the blocks of older sedimentary rocks upthrust by plate subduction. building of an accretionary wedge at the bottom of the slope. Sediments TINENTAL SLOPE Drilling is needed to obtain rock samples and confirm the shape have ponded behind these blocks to form the Cascade Bench off the uring the summer of 1984, marine scientists participat- and composition of these structures. north coast and the Klamath Bench off the south coast and northern ing in the dives of the deep-sea research vessel Alvin on California (see Figure 13). The lower slope below 2,000 meters is quite the Oregon continental slope discovered a prolific, deep- Continental Shelf steep and intersects the deep-sea bed of the Cascadia Basin at 2,200 ID sea benthic community (35). Tube worms, giant clams, meters off the north coast and 3,000 meters off the central and south carnivorous fish, and crabs were thriving in 2,036 meters of water, regon's continental shelf is a relatively flat, 'gently sloping coast (25). well below the range of sun-driven food webs. These animals were terrace. It is narrow in comparison with worldwide averages either identical or very similar to those found at the hot vents of the and ranges from about 17 kilometers (10 miles) off Cape Submarine Canyons midocean ridges, but the dominant source of energy on the Blanco to 74 kilometers (46 miles) off the central coast (24). In he outer edge of the continental shelf and continental slope is continental slope appeared to be methane, not hydrogen sulfide. general, the shelf is steepest where it is most narrow. The depth of the breached by two prominent submarine canyons and numerous On the continental slope, water rich in methane and nutrients is shelf varies but is usually taken to be 200 meters, at which point the shelf smaller ones. The Astoria Canyon cuts into the outer shelf about squeezed from the sediment of the Juan de Fuca plate as it merges with the steeper continental slope. U 16 kilometers (10 miles) west of the Columbia River. During subducts beneath the North American continent. This discovery The shelf has several prominent, rocky, submarine banks of varying size. periods of lowered sea level, the Columbia and Rogue Rivers drained interests scientists because although the emerging water is not Four major banks create locally shallow areas amidst the otherwise across what is now the continental shelf. The Astoria Fan, a large significantly warmer than the surrounding bottom water, a highly deeper water of the shelf: Nehalern Bank, Stonewall Bank, Heceta Bank, depositional feature on the eastern Cascadia Basin, lies at the base of productive deep-sea community has adapted to an environment and Coquille Bank. The rock blocks which form these banks have been the canyon. The Rogue Canyon is much smaller than the Astoria Canyon. of high pressure, low temperature, and very low productivity. uplifted by the underthrusting process at the base of the continental It begins near the edge of the shelf offshore of the Rogue River and feeds slope. directly down the continental slope onto the deep ocean floor. nQ SEDIMENTS OF THE CONTINENTAL SHELF In addition, calculations show that coastal erosion of sea terraces, cliffs, ..... ........... and other nearshore features could add as much as 600,000 cubic eologists studying sediments on the Oregon coast are ham- meters of sediment per year to the shelf. A third source, the U.S. Army ................ pered by lack of data from core samples. The Oregon conti- ........ Corps of Engineers' coastal dredging project, adds from 7 to 11 million .......... nental shelf, one of the least studied in the United States, has X: . ......... .... ...... cubic meters of sediment off Oregon per year into the ocean from been only superficially probed. Surface sediment distribution, .... ....... material dredged from Oregon's harbors and rivers (7). inferred from surface "grab samples," may not reflect the composition of ...... .... ...... deeper sediments (31). The inner shelf consists of sand derived from wave erosion of coastal ..... ...... ...... features and from coastal drainage, especially that of the Columbia Sediments found today on the continental shelf consist primarily of relict . ................ ................... River, which has been deposited onto a layer of clean, well-sorted sand .......... deposits, those laid down during the last advance in sea level, and those laid down during the last rise in sea level (34). Sediments of the middle .............. ... ........... .. which are being deposited under present hydrodynamic conditions (22). .......... and outer continental shelf tend to be very fine-grained muds of silt, clay, Sedimentation on the continental shelf is controlled by river discharge, and organic material. Patchy areas of muddy sediments appear to be estuarine circulation, wave characteristics, currents, density differences concentrated near rivers of high discharge, especially the Columbia in the water column, and benthic organisms. Nearshore surface sedi- River, where there is a high-volume discharge of fine sediments during ment distribution is mapped in Figure 9. ............. late spring and summer, a period of relative ocean calm. The mud layer is including the Rogue and quite thin or is entirely absent off central Oregon because of the low The Columbia River and other coastal rivers, .................... the Umpqua, supply the bulk of the sediment reaching the continental sediment supply from the small river basins of the north and central shelf. Sediment supply shifts seasonally with peak discharge of the coast (25). .......... ....... Columbia occurring in the late spring and early summer, several months Farther to sea, the outer shelf and upper continental slope are covered ... ................ after peak discharge of the smaller coastal streams. by poorly sorted, very fine sediment (34). These upper-slope sediments Estuaries can act as a settling basin for the larger sand-sized particles originated in streams of southern Oregon and northern California and carried in coastal streams so that only the finer suspended particles were transported northward by a north-flowing undercurrent over the ................... enter the ocean. However, during winter, high-volume river discharge ....... outer shelf and upper slope (25). into small estuaries carries river sand and gravel through and into the The burrowing of marine organisms is the principal way in which mud ......... . ocean. In summer, ocean beach sand is transported into estuaries by and sand are mixed. This action usually occurs in the transition area incoming tidal currents and is deposited along the margins of the between the nearshore deposits that are exclusively sand and the mud deposits farther offshore. estuary several kilometers from the mouth (32). Waves stir and lift shelf sediments for transport by currents on the shelf ............... (22). The winter wave regime off the Oregon coast is noted for its ........... ........... intensity, whereas summer waves are much less energetic (29). Winter D .................... storms generate long-period waves capable of rippling the sediment on ........... ...... ...... ........ ... the ocean bottom to depths of 150 to 200 meters across the entire width MNED !@-AND MUD Of the shelf. Lower-energy summer waves may produce ripples to depths of 50 to 100 meters. MUD Wave activity in the surf zone is important in lifting and transporting sand *AUCDN ITE- alongshore and in creating both a surface turbid layer and a midwater ............. ............................ ............. layer. This surface turbid layer of fine-grained materials can extend the width of the shelf, although its intensity will decrease with distance from .... .......... the source. The midwater layer consists of suspended material which has settled out of the surface layer and which moves across the shelf .................. ............ along a boundary of different water densities (22). ................ A third turbid layer develops on the bottom of the shelf in response to resuspension by surface waves, to bottom currents, and to the settling ......... . ............ . ......... of material from the surface and midwater layers. This layer can be as intense as the surface layer (22), Ac6er Kulm, 876 ....... Modern continental shelf sediments are derived from three principal Figure 16. Sediment Distribution on the Continental sources: river discharge, coastal erosion, and federally authorized Shelf dredging projects undertaken by the U.S. Army Corps of Engineers (22; 6). The large drainage basin of the Columbia River contributes approx- Sandy bottom is prevalent near the coastline; muddy areas and imately 11 million cubic meters (approximately three cubic miles) of mixed sand and mud occur farther out. Hard, mudstone rock suspended sediments each year to the ocean. Other major coastal outcrops at submarine banks are not covered by sediments. The rivers, the Umpqua and Rogue of Oregon and the Klamath of northern continental slope is covered with glauconite mud, an iron-rich sediment formed by chemical action in deep marine waters with a California, carry lesser quantities of sediments to the continental shelf. high organic content. Heavy-mineral sediments flow from the Klamath Mountains and are deposited in offshore placer deposits (see "Resources of the Continen- tal Shelf"). RESOURCES OF THE CONTINENTAL SHELF Figure 17. Gravel and Heavy Min- SHEJ-L - ----------- ----------------- io, /6 he geologic resources of the continental shelf are of increasing interest to industry and commerce. As onshore gravel deposits eral Deposits of the South Coast are depleted or allocated to other uses, deposits on the ocean A,%-r AgA6O Oregon's south coast has most of the floor may attract developers. Rare and exotic minerals, needed s offshore gravel deposits and a// of state (,f 70 1-r in sophisticated metallurgy, concentrate in deposits on the continental the heavy-mineral deposits. Gravel depos- shelf. Oil and gas reserves may lie buried in basins beneath the ocean its are small and patchy but relatively and may be increasingly important as society looks for alternatives to shallow. Heavy-mineral deposits are relict depleted land reserves. Oregon's continental shelf could be the site for concentrations from periods of lower sea UNION level. .12,62 5Fr development of some of these resources. (125 Fr. aP WATF-") Gravel Deposits rANPARD/UNION ............. he gravel deposits on Oregon's continental shelf are relicts of a &4ANe'o ..... .......... .................... time dating from approximately 15,000 years ago when sea level 0 P@F_GrON F7- was about 200 meters lower than it is today (29). Surf action . .....-..... during the rise in sea level concentrated gravels in small pocket ............ . . . beaches between what are now submerged ridges. The active wave 4 FM CZJ@M HEA@f environment along those rocky shores carried away the smaller sand- or 11111111111111111HORC THAN 20% ..........- silt-sized sediments and left the heavier gravels. Oregon's larger gravel UN10N MLE% TfM 2ex bodies are situated in depressions between submarine banks. Other )W*Q5 Rivex- .............. I..... Y smaller gravel deposits lie near submarine rock outcrops. ........... Figure 18. Exploratory Wells Gravel deposits off Oregon are relatively small and localized (see Figure Drilled In Federal Waters, 17). Major Oregon offshore deposits, which lie in shallow water, are !5,:' A L@ F@ 6- 1967-69 PAtq-AMEPJ(,A?`4 ------ located near Stonewall Bank (60 meters); between Heceta and Stone- ... ....... Eight exploratory wells were drifted as wall Banks (100 meters); at Cape Arago (70 meters); off the Coquille River (60 to 70 meters); at Cape Blanco (40 meters); and off Humbug % part of the U.S. Department of Interior's % offshore oil exploration program. None Mountain (40 meters) (29). Recent dredging by the U.S. Army Corps of A&@ PIWAMO revealed commercial quantities of hydro- ................ Engineers indicates that deposits may be present at the mouth of the carbons. Rogue River. Geologists suspect these deposits lie in former river ............ channels that once cut across the continental shelf. Estimates of the ............. volume of gravel deposited off Oregon range from 100 to 500 million It appears that major deposits occur on the southern Oregon shelf off the ........... .. ......... cubic meters. mouth of the Rogue River and off Cape Blanco at depths varying from 20 . .......... By contrast, gravel deposits off the Washington coast are extensive and to 100 meters. The offshore Rogue deposit is approximately 37 kilo- buried organisms into petroleum and natural gas, much as are the result of a different geologic process. Vigorous meltwater meters long and extends to a depth of 90 meters. This area contains 20 ancient forests were converted into coal. streams from retreating continental glaciers in Canada and alpine to 30 percent heavy minerals. The Cape Blanco deposit is less extensive glaciers of the northern Cascade and Olympic mountains carried tre- but contains a higher mineral concentration. Approximately 13 kilo- The compacting pressure of the ancient sediments also mendous volumes of gravel to be deposited in broad fans on the meters long and 6 kilometers wide, it is found in water depths ranging changed the clays, silts, and sands into rock: shale, continental shelf. These large deposits are located off the Strait of Juan from 30 to 55 meters. This volume of these deposits is not yet known mudstone, or sandstone. Oil and gas, squeezed from the (21). denser source rocks such as shale, migrated into porous de,Fuca and off the Chehalis and Quinalt rivers. South of Cape Arago, rapid uplift of the coast has preserved heavy sandstone and limestone. Placer Deposits mineral deposits onshore. These deposits were mined for chromite As the earth's crust fractured or folded, the shifting layers of uried off the Oregon coast are layers of sediments containing during World War 11 and until the late 1950s. Mining ceased when the rock formed traps, barriers to the oil's migration. Lying next to high concentrations of heavy minerals-chromite, ilmenite, federal government discontinued subsidy of the mining operations (36). or beneath impermeable rock, a reservoir was formed, hold- magnetite, zircon, and traces of gold (21) (see Figure 17). ing a pool of natural gas and petroleum above a deeper layer IM These mineral-rich deposits, known as placers, are of two Oil and Gas Deposits of water. (30) kinds: relict deposits, which were formed during lower sea level stands, il and gas are hydrocarbons, chemical compounds once part Onshore hydrocarbon deposits at Mist in northwestern Oregon have and modern deposits, which are currently being formed. The process of of living organisms which have been buried, heated, and been tapped for several years. Conditions favoring the formation of formation is the same for both kinds. squeezed into new forms. source rock and traps appear to be present off the Oregon coast; The minerals originate in the mountains of southern Oregon and northern Oil's origin lay in the sunlit, shallow, coastal waters of however, the uplift and deformation of the continental margin have California. The Rogue, Sixes, Chetco, Klamath, and other rivers drain ancient seas, where vast numbers of tiny marine plants and resulted in very complex structures which are difficult to analyze. . these mountains, discharging sediments rich in heavy minerals into the animals flourished, As countless generations of these organ- Exploration for oil and gas off the Oregon coast has been sporadic since surf zone. Waves and currents sort the heavier mineral grains from such isms grew and died, their remains settled to the seafloor and the early 1960s. Of the eight exploratory wells drilled in federal waters lighter ones as quartz and feldspar. Winter longshore currents carry were covered by fine particles of clay, silt, or sand. (beyond three miles from the shoreline) from 1965 to 1967 (see Figure sediments northward until a major headland interrupts the flow and the 18), only one produced hydrocarbons, although not in commercial heavy minerals settle out. In summer, the currents shift and carry the This process, repeated through thousands of years, led to quantities (39). Even though commercial quantities have not yet been lighter minerals south, enriching the deposit. Over thousands of years, the accumulation of dense sediments on the ancient seabed. found, interest in these areas remains as oil companies conduct geologic this sorting has resulted in concentrations of similar mineral types into The weight of these sediments, combined with certain chem- studies off the Oregon coast. "lenses" along the shore. ical, bacterial, and temperature conditions, transformed the &ECLOOV tQ THE COASTLINE regon's relatively young, straight coastline is the remnant of rapidly rising sea level and lack of sedimentary buffer along the shoreline. Under these conditions, the Pacific Ocean 22 20-7 actively attacks and erodes promontories while simul- taneously filling and straightening embayments. Interaction between the nearshore wave environment and local geology produces a unique set of shoreline features. @57_11W) A The shape and depth of the shelf just offshore and the direction of wave A approach are major factors in how the wave energy affects the shoreline Figure 21. Seasonal Beach Profiles (see Figure 19). Capes, headlands, and reefs projecting into the ocean 4 tend to focus wave energy on themselves. Thus, only the most resistant Sand accumulation on beaches is different in summer than in J Vvi of rocks can long withstand the increased pounding of waves. Over time nter. High-energy winter storms pull sand from beaches and deposit it as offshore bars; low-energy summer swe/l pushes sand this relentless focusing of the ocean's energy either will erode and remove the promontory or will gnaw away at both sides of the landward back up onto beaches into a high berm. end of an especially resistant formation until the rock is encircled by the ocean and exposed to attack from all sides (see Figure 20). Along beach fronts and embayments, however, the energy of ocean waves is dissi- IV. 17 pated, allowing sediments to settle out, thus tending to fill these indentations. ------------------ - -- WAVE SNEFar f!'OTTOM .. . .. ... Figure 20. Aerial View of Wave Refraction Around Offshore Rocks Waves moving through the water are bent (refracted) around offshore rocks and islands. This refraction is visible around rocks offshore of Port Orford in Curry County. FCC44ST The direction of longshore transport varies seasonally with wind direc- tion. Generally, beach sediment is moved south in the summer and north in the winter, although local variations can occur. Every beach has a "sand budget." If the amount of sand deposited on the beach is beach and surge to the foot of coastal cliffs. Erosion is most severe balanced with the amount being removed, the beach is in equilibrium. If Figure 19. Wave Refraction during this time, particularly of the cliffs and terraces of softer sedimen- not, a change in the beach will occur. Wave fronts (shaded bands) approaching the shoreline are bent tary rock. Waves pull sand from the beach and deposit it beyond the Man-made structures like jetties interrupt longshore transport. Winter (refracted) by ocean bottom contours and promontories (solid active surf zone as offshore sand bars. In the summer, wave conditions longshore transport along the Oregon coast is south to north; sand, lines). Wave energy (dashed lines) is focused onto projecting are less harsh and sand is returned to the beach. A wide summer beach trapped on the south side of the jetties, causes the beach to grow features and diffused in embayments. buffers. the cliffs and dunes from wave erosion. seaward. Summer longshore currents move from north to south so that Beaches are also influenced by currents flowing parallel to the shoreline. beach growth occurs behind the north jetty at river mouths. The While the lifespan of some coastal features varies over geologic time, When waves approach the shore at an angle and break in the surf zone, accompanying aerial photo shows how sand has accumulated behind others respond to seasonal fluctuations. Beaches are transient, ever- part of their energy will go into pushing a longshore current. The larger both jetties at the mouth of Tillamook Bay. changing landforms responding almost overnight to the action of waves, the waves or the gr 'eater the angle of approach,.the stronger this Rip currents also play an important role in the movement of sediment currents, and wind. Seasonal changes in the beach face result from longshore current. Wave action keeps sediment suspended in the water, and shaping of beaches (see Figure 14). When longshore currents from water sweeping onto the shore and off again (see Figure 21) (19). Storm and the larger the waves the more sediment that can be moved. This opposite directions meet, water is forced out to sea in a rip current. waves, driven by strong winds and high tides, break directly onto the transport mechanism can move tremendous amounts of material during Likewise, when a longshore current meets a headland or jetty, a rip winter storm conditions. current is commonly observed alongside those features. (17) E@01-rOM Seismic sea waves or tsunamis are generated by violent displacement of the sea bottom, for example, by an earthquake or a landslide. Although tsunamis are of relatively small height in the open ocean (less than lb meter) (2; 3), they can move quickly across the surface of the ocean as a ----------------- series of high-velocity, long-period waves. In parts of the Pacific their ---------------- speed can exceed 720 kilometers (447 miles) per hour. RIP, (A) When the tsunami finally reaches the shallow waters of a coastal area, its --------- height can be tremendous. The 1964 Alaska earthquake triggered a tsunami that produced waves onshore which ranged from 1 to 5 meters (3.3 to 16.5 feet) above mean high water. These waves appeared At intervals and surged into several Oregon estuaries and the waterfront area of Crescent City, California, causing extensive flooding, destruction of property, collapsed bridges, and loss of life (37). DIRtr-77oN WAVE MOTION Figure 22. Nearshore Circulation: Longshore and Rip Currents Rip currents are produced when longshore currents meet the WAV e .......... . headland (A) or where a bottom depression (B) allows a longshore current to flow seaward. -b- PaF@ Figure 23. Effects of Man-Made Structure on Long- shore Current In winter, jetties at the mouth of coastal rivers, as here at Tillamook WIND WAVES AND TSUNAMIS Bay, interrupt the sediment-laden longshore current flowing north aves are created primarily by wind, but they can also be and cause a sediment load to be deposited on the south side (the caused by underwater landslides and earthquakes. When upstream side). Sand accumulates on the north side by means of a Figure 24. Diagram: Parts of a Wave strong summer longshore current driven by northwest winds. This wind blows across the ocean, the friction between the air backfilling will occur until the profile of the ocean front is again in In an ideal wave, water rises and falls in an orbital motion as wave and surface of the water forms waves. The size of the wave equilibrium. energy moves through the water. Wave energy is strongest at the is determined by how fast the wind blows, how long it blows, and how far surface (large circles) and decreases rapidly with depth. The wave over the water it blows. Storms blowing in the open ocean create a period is the time it takes for a wave crest to traverse a distance frenzy of waves called a sea (2). As waves leave the storm-generating equal to one wave length. area, they become sorted according to their period. Shorter-period waves are left behind and longer waves of similar period and height form lower, more rounded, powerful waves called swell. Swell moves across the open ocean toward distant shores in groups of waves called trains. A train whose wave period averages twelve seconds will take two days to cross 1,000 miles of open ocean (2). These trains can travel great distances with little energy loss; swell generated in the Antarctic has been detected on the Alaska coast (38). As waves move over the continental shelf and into water where the Waves reaching the Oregon coast respond to the seasonal wind depth is less than half the wave length, their characteristics begin to patterns in the Pacific Northwest: in summer, the predominant wave change. Waves moving into shallow water become unstable because approach is from the northwest and in winter from the southwest. The their height increases quickly relative to their length. Eventually, they highest waves are always in the winter when the wind blows many hours oversteepen and break. Breaking waves generate back-and-forth cur- at high, velocities. Exceptional storm wave heights were observed from rents along the bottom that contribute to sediment transport near the an oil rig off the Oregon coast in 1968 where waves up to 18 meters (59 shore and even out to the edge of the shelf (37). feet) and even one of 29 meters (96 feet) were recorded (41). REFERENCES 25. Kulm, L. D., and K. Scheidegger. 1979. Quaternary Sedminentation on the Tectonically Active Oregon Continental Slope. Pages 247-263 in Doyle and Pilkey, editors. Geology of Continental Slopes. Special Publication No. 27, Society of Economic Paleontologists Note: References are cited in text by number, References marked with an asterisk (*) are and Mineralogists, Tulsa, Oklahoma. recommended because they are comprehensive, easily understood and accessible. 2& Kulm, L. D. 1985. Personal communication. College of Oceanography, Oregon State 1 .Baross, J. A., and S. E. Hoffman. In press. Submarine Hydrothermal Vents and University, Corvallis, Oregon. Associated Gradient Environments as Sites for the Origin and Evolution of Life. In 27. Malahoff, A. 1982. Massive Enriched Polymetallic Sulfides of the Ocean Floor-A New Global Habitability and Chemical Evolution. Reidel Press, New York, New York. Commercial Source for Strategic Minerals? Paper Presented at the 14th Annual 2. *Bascom, W. 1964. Waves and Beaches. Doubleday and Company, Inc., Garden City, Offshore Technology Conference. New York. 28. McKee, B. 1972. Cascadia: The Geologic Evolution of the Pacific Northwest. McGraw- 3. Beaulieu, J. D. and P. W. Hughes. 1975. Environmental Geology of Western Coos and Hill, Inc., New York, New York. Douglas Counties. Oregon Department of Geology and Mineral Industries, Bulletin 87, 29. Moore, G. W., and M. D. Luken, 1979. Offshore Sand and Gravel Resources of the Portland, Oregon. Pacific Northwest. Oregon Geology 41(9):143-151. 4. Byrne, J. V., G. A. Fowler and N. J. Maloney. 1966. Uplift of the Continental Margin and 30. *Stander, J. M., and R. L. Holton, editors. 1978. Oregon and Offshore Oil. ORESU-T-78- Possible Continental Accretion Off Oregon. Science 154:1654-1656. 004. Oregon State University Sea Grant, Corvallis, Oregon. 5. Canadian American Seamount Expedition. 1985. Hydrothermal Vents on an Axis 31. Peterson, C. 1985. Personal communication. College of Oceanography, Oregon State Seamount of the Juan de Fuca Ridge. Nature 313(5999): 212-214. University, Corvallis, Oregon. 6. Chesser, S. 1984. Personal communication. U.S. Army Corps of Engineers, Portland, 32. Peterson, C., K. Scheidegger, and P. Komar. 1982. Sand-Dispersal Patterns in an Oregon. Active-Margin Estuary of the Northwestern United States as Indicated by Sand 7. Clague, D., and W. Friesen, et al. 1984. Preliminary Geological, Geophysical, and Composition, Texture and Bedforms. Marine Geology 50:77-96. Biological Data from the Gorda Ridge. Pages 84-364 in UnitedStates Geological Survey 33. Riddihough, R. 1984. Recent Movements of the Juan cle Fuca Plate System. Journal of Open-File Report, Menlo Park, California. Geophysical Research 89(B8):6980-6994. 8. Couch, R., and D. Braman. 1979. Geology of the Continental Margin Near Florence, 34. Runge, E. J. 1966. Continental Shelf Sediments, Columbia River to Cape Blanco, Oregon. Oregon Geology, 41:171-179. Oregon. Doctoral dissertation. Oregon State University, Corvallis, Oregon. 9. Downing, J. 1984. The Coast of Puget Sound. Washington Sea Grant, University of 35. Suess, E., B. Carsons, S. D. Ritger, J. C. Moore, L. D. Kulm, and G. R. Cochrane. 1985. Washington, Seattle, Washington. In M. L. Jones, editor. The Hydrothermal Vents of the Eastern Pacific: An Overview. 10. *Drake, E. 1982. Tectonic Evolution of the Oregon Continental Margin. Oregon Geology 36. Snow, D. 1985. Personal communication. Oregon Department of Fish and Wildlife. 44:15-21. 37. *Summary of Knowledge of the Oregon and Washington Coastal Zone. 1977. Volume 11. Edmond, J. M. 1982. The Chemistry of Ridge Crest Hot Springs. Marine Technology 1. Oceanographic Institute of Washington, Seattle, Washington. Society Journal 16(3):23-25. 38. Thomson, R. E. 1981 . Oceanography of the British Columbia Coast, Canadian Special 12. Flint, R. F. 1971. Glacial and Quaternary Geology. John Wiley, New York, New York. Publication of Fisheries and Aquatic Sciences 56, Department of Fisheries and 13. *Francheteau, J. 1983. The Oceanic Crust. Scientific American 249(3):114-129. Oceans, Sidney, British Columbia. 14. Grassle, J. F. 1982. The Biology of Hydrothermal Vents: A Short Summary of Recent' 39. United States Geological Survey. 1969. Mineral and Water Resources of Oregon. Findings. Marine Technology Society Journal 16(3):33-38. Pages 283-290 in State of Oregon Department of Geology and Mineral Industries 15. Griggs, G., and L. D. Kulm. 1970. Physiography of the Cascadia Deep-Sea Channel. Bulletin 64. Portland, Oregon. Northwest Science 44:82-94. 40. *Waldrop, M. M. 1980. Hot Springs and Marine Chemistry. MOSAIC 11(4):8-14. 16. *Hiatt, B. 1980. Sulfides Instead of Sunlight. MOSAIC, 11(4):15-21. 41. Watts, J. S. and R. E. Faulkner. 1968. Designing a Drilling Rig for Severe Seas. Ocean 17. Holman, R. 1985, Personal communication. Oregon State University, Corvallis, Oregon. Industry 3(11):28-37. 18. *Kennett, J. 1982. Marine Geology. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 19. Komar, P. D. 1976. Beach Processes and Sedimentation. Prentice-Hall, Inc., Inglewood Additional Reading Cliffs, New Jersey. As the Oceanbook went to press, the National Geographic Magazine published the 20. Komar, P. D., R.H. Neudeck, and L. D. Kulm. 1972. Observations and Significance of August, 1985, issue. In that issue is the article "Our Restless Planet Earth," by Rick Gore. A Deep-Water Oscillatory Ripple Marks on the Oregon Continental Shelf. Pages 601-619 fold-out supplement, entitled "The Shaping of a Continent: North America's Active West," in D. J. P. Swift, D. B. Duane, and 0. H. Pilkey, editors. Shelf Sediment Transport. contains a three-dimensional drawing of the plate tectonic activity of the Pacific Northwest Dowden, Hutchinson, and Ross, Stroudsburg, Pennsylvania. with focus on the Juan cle Fuca Plate and Gorda Plate as they are subducted beneath North 21. Kulm, L. D., D. F. Heinrichs, R. M. Buehrig, and D. M. Chambers. 1968. Evidence for America. Interested readers will find the magazine article and supplement to be a Possible Placer Accumulations on the Southern Oregon Continental Shelf. The ORE fascinating and beautifully illustrated complement to the Oceanbook. The full citation is: BIN, 30(5):81-104. Gore, R. 1985. Our Restless Planet Earth: National Geographic Magazine 168/2: 142-181. 22. Kulm, L. D. 1978. Coastal Morphology and Geology of the Ocean Bottom-The Oregon Edmond, J. M. 1984. The Geochernistry of Ridge Crest Hot Springs: Oceanus Fall 1984, Region. In R. Krauss, editor. The Marine Plant Biomass of the Pacific Northwest Coast. 27/3: 15-19. Oregon State University Press, Corvallis, Oregon. Jannasch, H. W. 1984. Chemosynthesis: the Nutritional Basis for Life at Deep-Sea Vents: 23. Kulm, L. D., and G. A. Fowler. 1974(a). Cenozoic Sedimentary Framework of the Gorda- Oceanus Fall 1984, 27/3: 73-78. Juan De Fuca Plate and Adjacent Continental Margin-A Review. Pages 212-229 in R. Jeanloz, R. 1983. The Earth's Core: Scientific American Sept. 1983, 249/3: 56-65. H. Dott, Jr., and R. H. Shaver, editors. Modern and Ancient Geosynclinal Sedimenta- Katz, B. A. and S. R. Gabriel. 1977. Oregon's Ever-Changing Coastline, Oregon State tion. Special Publication No. 19, Society of Economic Paleontologists and Miner- University Extension Marine Advisory Program Publication SG 35, Corvallis, Oregon. alogists, Tulsa, Oklahoma. Lonsdale, P. 1984. Hot Vents and Hydrocarbon Seeps in the Sea of Cortez: Oceanus Fall 24. Kulm, L. D., and G. A. 'Fowler. 1974(b). Oregon Continental Margin Structure and 1984, 27/3: 21-26. Stratigraphy: A Test of the Imbricate Thrust Model. Pages 247-263 in C. A. Burke and C. *McKenzie, P. D. 1983. The Earth's Mantle: Scientific American Sept. 1983, 249/3: 66-78. L. Drake, editors. The Geology of Continental Margins, Springer-Verlag, New York. *Siever, R. 1983. The Dynamic Earth: Scientific American Sept. 1983, 249/3: 45-56. Somero, G. N. 1984. Physiology and Biochemistry of the Hydrothermal Vent Animals: Oceanus Fall 1984, 27/3: 67-73. Turner, R. D. and R. A. Lutz. 1984. Growth and Distribution of Mollusks at Deep-Sea Vents and Seeps: Oceanus Fall 1984,27/3: 54-63. CHAPTER THREE -1 The Water 1, Winds of the Atmosphere and Their Influence on the Ocean Two major atmospheric pressure cells over the northeast Pacific affect he sun is the source of energy that drives the circulation Oregon's weather: the North Pacific high and the Aleutian low (see patterns of the earth's atmosphere and oceans. Solar radiation Figure 25). Air- flows clockwise around the high-pressure cell and is not evenly distributed over the earth's spherical surface, but counterclockwise around the low-pressure cell. (See satellite photo of intensifies in equatorial regions and diminishes at the poles. This storm systems, Figure 26.) Surface winds spiral in rotary fashion around uneven heating, coupled with the shape and size of the continents and these pressure gradients. (A storm system spins counterclockwise as it ocean basins, creates a series of atmospheric circulation cells. slides from the Aleutian low around the North Pacific high toward the coast.) INTRODUCTION arth is unique among the planets in our solar system in that 70 percent of its surface is covered by water, principally in the 2145 29MY76 32A-1 00801 15951 WB2 oceans. No mere basins of still water, oceans are dynamic systems of vast currents and tremendous energy driven by the sun's heat, the earth's spin, and the moon's pull. Earth's yearly journey around the sun creates a cycle of seasons in the oceans, especially near the coastline. Water is an impressive substance. The marvelously simple structure of the water molecule is essential to the roles it plays in our envi ronment-cl i mate control, food production, ocean circulation, and waste disposal, to name a few. WNT7.9. Although churning surf driven before a winter storm is an unforgettable - IW P sight, the ocean's most important feature, its internal composition, cannot be seen by the naked eye. Add the vast size and great depth of the ocean and the task of measuring and understanding the ocean @Pr becomes a formidable challenge. Understanding of the ocean advances slowly as marine scientists gather ATM05@@EA'IC bits of information at selected points. Typically, they make observations CIRUk-ATION of ocean currents or seawater content by direct sampling. These observations are individual scenes of the ocean's condition at the point of measurement, and many scenes over a wide area over a long period TM PACII Icr may generate a motion picture of the ocean's dynamic conditions. Scientists must analyze and visualize the abstract data to construct a working model of the ocean. @_-UMMER_ UPLULATIC" This chapter of the Oceanbook describes how the earth's atmosphere _777 @77 Ptl jr influences weather and ocean circulation patterns in the Pacific North- 'WV1 r west. It discusses temporal variations in ocean circulation, those which W occur over a span of from several days to several years, such as upwelling and El Nino, an occasional and unwelcome visitor to Oregon's ocean. Finally, the Oceanbook examines the physical and chemical Figure 26. Satellite View of North Pacific Ocean characteristics of seawater, the influence of the Columbia River flow on MW 'rAPATA Cloud Cover the ocean, and the effect of all three on the ocean's structure,and Figure 25. Major Circulation Patterns in the Atmo- A late spring storm is shown whirling ashore over the Pacific productivity off Oregon. sphere and Ocean Northwest. The center of this counterclockwise spiral is just west of In winter, the large Aleutian low dominates the weather of the the northern tip of Vancouver Island. Clearing skies and cooler air ATMOSPHERIC CIRCULATION AND OCEAN northern Pacific Ocean (top left). Storms move counterclockwise will soon follow this Memorial Day storm. Far at sea, south of the SURFACE CURRENTS around the low, slide off the north side of the North Pacific high, and Aleutian Island chain, another low-pressure cell is beginning to blow onshore from the southwest. (Atmospheric pressure gradients coalesce before moving eastward toward Oregon. (NOAA photo.) tmospheric conditions and ocean currents may be examined at are shown in millibars.) several levels of detail, in a sense adjusting the degree of In summer, the North Pacific high moves northward off Oregon and magnification of the microscope, selecting all or merely a northern California. Winds circulate clockwise around the high and portion of the ocean for study. Beginning with a satellite blow north to south along the Oregon coast. panorama of the entire earth or an entire ocean basin, we may then Ocean circulation in the north Pacific Ocean reflects large-scale air increase the magnification to more closely observe regional atmospheric movements. The North Pacific gyre, composed of numerous cur- The constant movement of air around these pressure cells delivers and oceanic circulation and finally the winds and currents in a particular energy to the surface of the ocean. Thus, the surface circulation of the locale. This method of zooming in, which is used in the Oceanbook, rents, is narrow and strong on the west side of the ocean basin, North Pacific Ocean is influenced by the direction and size of atmo- broad and slow on the east side. A similar gyre in the South Pacific starts with a general picture which is then refined by overlays of more circulates in the opposite direction. spheric flow, particularly the North Pacific high. specific information. The North Pacific gyre is the great clockwise ocean circulation system Winter flow (December to February) is northward at all depths over the spun from the North Pacific high. Although it encompasses virtually the continental shelf in response to the southwest winds. It is referred to as entire North Pacific basin, the gyre is displaced toward the west side of the Davidson Current (see Figure 28). It is a fast current, more than 150 the Pacific Ocean by the earth's rotation. As a result, currents along the kilometers wide (wider than the continental shelf) (6), and forms a band coast of Japan are fast (40 to 112 kilometers per day) and narrow N09TH '@Z of low-salinity water from coastal runoff at least 90 kilometers wide (12). whereas those along the North American coast are slow (less than 10 The Davidson Current extends from northern California to the Strait of kilometers per day) and wide (22). Juan de Fuca and coincides with the direction of prevailing winter storm . ....... winds. This gyre is a composite of many different surface water masses and currents, each with distinguishing physical and chemical characteristics. Transition to the regime of spring and summer circulation is accom- Surface ocean currents flowing past the Oregon coast form part of the plished over one or two days in response to a shift in the seasonal wind Subarctic Current, a broad, slow, cold current drifting easterly across the direction. Sea level falls as the North Pacific high sets in, bringing high northern Pacific Ocean within the North Pacific gyre. Near the coast of atmospheric pressure and a reverse flow in currents. North America this current divides in two: the Alaska Current loops north into the Gulf of Alaska, and the California Current swings southward along the Pacific coast (21). Figure 27. Summer Circulation off Oregon The California Current, a broad, shallow surface current, drifts slowly southward over the continental shelf and slope during the summer. The California Undercurrent is a narrow, faster-moving Horizontal Circulation along the Oregon Coast current flowing northward at depths greater than 200 meters over the continental slope. This schematic diagram is not to scale. uch of the information presented on nearshore horizontal circulation is based on direct observations taken from cur- Vertical Circulation along the Oregon Coast rent meters placed along the.Oregon coast to record speed, MOR-TH pwelling, an important ocean phenomenon, results from an direction, and temperature at regular 10- to 20-minute inter- WINTF-P- CIROULA7101Y. unusual set of conditions most common along the west coast vals. Although these measurements, taken over a period of several of North and South America, the west coast of Africa, and years, were widely spaced north and south, the data obtained can begin ------- southern Europe. In coastal regions upwelling provides a to describe general patterns of the ocean circulation system. Preliminary consistent supply of nutrients that makes these waters some of the most analysis suggests that currents are similar over alongshore distances of productive in the world (15). up to 200 kilometers (9) and across the width of the shelf (7). In Oregon, strong northwest winds begin in the spring and usually Further analysis of current meter data indicates that ocean circulation off continue into the fall. As these winds blow south along the coastline, the Oregon coast responds principally to wind fluctuations and sea level. they produce currents which divert water to the right of the wind Currents over the shelf tend to flow in the same direction as the wind, direction as a result of the Coriolis force (an effect of the earth's rotation) south in the summer and north in the winter, not only at the surface, but (see Figure 29). Studies off the central Oregon coast show that the to the bottom. Currents also correlate closely with sea level, flowing surface layer in which the wind-driven offshore transport occurs is northward when sea level is high and southward when it is low. These relatively thin-less than 20 meters deep (17). This offshoreflow of water general patterns become more complex when seasonal or localized is replaced by an onshore flow of colder, nutrient-rich water that rises conditions are considered. Figure 28. Winter Circulation off Oregon from depths of 100 to 200 meters. Vertical velocities of this onshore flow On average, currents over the continental shelf and slope flow south at The fast-moving, relatively narrow Davidson Current flows north- vary but have been estimated to be as much as 17.3 meters per day (12). the surface and north along the bottom. This general behavior of ocean ward at a// depths over the continental shelf. The California Current, Vertical flow is strongest near the surface and decreases rapidly with currents can be further refined for seasonal conditions. The summertime flowing slowly southward on the surface, is pushed offshore by the distance from shore (7). southward-f lowing surface current responds to the northwest winds. It is I Davidson Current. This schematic diagram is not to scale. Since the upwelled water now at the surface nearshore is denser and called the California Current, a poorly defined and variable extension of colder than the water it replaced, now farther offshore, a strong onshore- the Subarctic Current. It is broad, approximately 500 to 1000 kilometers offshore pressure difference in the water column is established. This wide, and weak, moving an average of 4 to 8 kilometers per day (3). east-to-west gradient leads to lowered sea surface levels at the coast During the summer its speed may more than double within 100 kilo- and causes a southward surface current called a coastal jet whose meters of the coast (see Figure 27), reinforced by extended periods of velocity is greatest (approximately 25 centimeters per second) 15 to 20 northwest winds (21). kilometers from shore (8). In summertime, the California Undercurrent is narrower, approximately provide a feedback loop for nutrients which sink out of the productive As the local wind stress varies from day to day and from season to 50 kilometers wide, and faster than the overlying California Current. It surface waters to deeper water. These particles and dissolved sub- season, significant variations in the strength of coastal upwelling occur. flows northward, flowing over the continental slope at depths below 200 stances can be transported back upstream and returned to the surface Most upwelling occurs as a series of pulses or "events" with a time scale meters (see Figure 27). The undercurrent, which originates off California, through upwelling (19). of days to weeks, as long as winds are favorable. When these northwest is believed to be linked to the equatorial Pacific water masses because In fall (late August and September), the southward surface current winds cease, warmer sea surface temperatures return to the area in a of its slightly warmer temperature and higher salinity (3). This "pole- weakens and disappears. It is replaced by an increasingly strong matter of days, Upwelling events can occur even in the winter when ward" (so named because it flows toward the North Pole) current may poleward undercurrent that responds incrementally to each northward winds, generally from the south, shift direction and create the necessary wind event of the oncoming winter, conditions for upwelling (8). no UO aciumoan&pmv Eddies 'Alw-jol'a@ atellite surveillance is a recently developed tool which is assist- ggc q ing in the study of large-scale ocean circulation features (20). @,7 5@ Satellite images of the California Current reveal several eddies between Baja California and Vancouver, British Columbia. As large as 150 kilometers in diameter, these eddies rotate clockwise at about one kilometer per hour and drift slowly southward with the current (16). Their origin and extent have not yet been determined, but their formation and behavior appear to be linked to features on the ocean 44 bottom such as the Mendocino Fracture Zone and to coastal features such as Point Conception in southern California. El Nino uring the winter of 1982 and spring of 1983, an unusual set of ocean conditions occurred off the west coast. Sea tem- pe M+- KNAUSS, 178 ratures were unseasonably warm, high seas and tides slammed onto the Pacific coast, causing substantial erosion, and heavy rains repeatedly drenched California. In Oregon, although upwelling may have continued, the cold, nutrient-rich water was Figure 29. Offshore Water Transport and Upwelling replaced by warm, nutrient-depleted water which had a marked influ- Wind blowing across the water sets up a spiral of water movement ence on the decline in fish harvest (19). These conditions are associated with El Nino, a periodic phenomenon noted and best studied off the within the upper 20 to 40 meters of the surface. The result is a slow movement of this surface layer at right angles to the wind direction. coast of South America. Off Oregon, strong north winds in summer result in water moving The causes of El Nino are not known exactly, but a clearly important seaward; deeper, nutrient-rich, high-salinity water flows shoreward relationship exists between the atmosphere and' the oceans (10). The and upwells into surface layers. A fast, narrow coastaljet develops initial manifestations of El Nino off Oregon were noted in October 1982: along the coastline, moving in the direction of the wind. anomalously high sea level, high coastal sea surface temperature, and increased poleward flow. These oceanic conditions occurred within one month of the onset of El Nino off Peru and preceded any atmospheric effect in the North Pacific by two to three months. The atmospheric conditions appeared in December and January, enhancing the initial Active upwelling is restricted to a narrow band ranging from 10 to 30 effects and then inserting their own signal. kilometers from shore, but it may influence a much larger region. Satellite During a normal year, a persistent high-pressure system prevails over infrared photos show that colder upwelled water is swept offshore as the western Pacific near Malaysia and a low-pressure system over the patches, tongues, and plumes that continually change shape (see Indian Ocean. The pressure differential causes tradewinds to blow Figure 30). westward across the Pacific. In addition, the Peru and California Cur- rents (see Figure 25) meet at the equator and then swing westward as Just as wind direction influences horizontal surface flow, changes in the South and North Equatorial Currents, respectively. The tradewinds, wind direction can result in changes in vertical circulation. During winter, combined with the westward-f lowing equatorial currents, cause warm when winds frequently blow to the north, downwelling occurs. These water to pile up in the western Pacific. north-blowing winds cause water surface transport to shift onshore (to In an El Nino year, the atmospheric pressure system breaks down. As the the right), Water then "piles up" at the coast and, having nowhere to go, tradewinds relax, the westward-flowing equatorial currents subside. In sinks and then moves offshore. the absence of the forces needed to maintain high sea level in the Upwelling, a product of seasonal winds, in turn strongly influences the western Pacific, a slosh of warm water begins to flow back across the climate of the coastal area and by extension the entire Pacific Northwest ocean (19). When this water reaches the Americas, it spreads north and (13). Nearshore upwelled water is cooler than offshore water; warm south along the coast. It is first detected by a slight rise in sea level. marine air passing over these waters is cooled and forms fog. This cool, Later, weather and oceanic conditions such as those observed during foggy air is pulled landward by warm air rising over inland areas. the winter of 1982 and spring of 1983 begin to appear. Figure 30. Infrared Satellite Photo of Upwelling An infrared scan of the Pacific coast from Vancouver Island to just Deep Ocean Circulation south of Monterey Bay, California (NOAA satellite, September 11, ff Oregon, a deep poleward current has been verified over the 1974, from 1, 500 kilometers), shows cold, upwelled water as lighter continental slope in spring and early summer (7). Little is grey areas along the coastline. Warmer water offshore shows as darker grey. Clouds (upper right comer) appear white. Upwelled known of the deep ocean circulation off the Oregon coast water forms tongues and plumes which continually change. beyond the continental slope since there are few direct measurements. PHYSICAL PROPERTIES OF THE OCEAN TYPICAL, VERTICAL, OCEAN 3TRUCTURE, large part of physical oceanography is concerned with the distribution of salinity, temperature, and ultimately, density of LSUBARC71-C PA C h @ `IC the ocean. Much can be learned by observing small variations 1j% in these properties: how oceans circulate, how heat is exchanged across the ocean surface to maintain a relatively constant global temperature, and how sound waves behave in the ocean. A7-/v/0.5/0/X!S/C/C Yl " 77: L_ @ If, / YC f t 5 Salinity HEATINCT MEOPITATION' eawater is a complex fluid, approximately 96.5 percent pure COCUN(@F EVAPORATION water and 3.5 percent dissolved salts. These salts include sodium chloride (common table salt), magnesium, sulfate, cal- cium, potassium, and other constituents in smaller amounts. A typical 1-kilogram sample of seawater will contain about 19 grams of chlorine, 11 grams of sodium, 1.3 grams of magnesium, and 0.9 gram of TEMPER-ATUR-E- 5AL-INITY sulfur (5). Salinity, the saltiness of the water, is measured in parts per 60KFAGE ............. )10.ljyop,@Aer ........ INC-PEA5E, ....... ........................... thousand (o/oo). The average salinity of the world's oceans is 35 o/oo. (2). ZONE, OF SEA50NAL Temperature ith a few exceptions, the temperature of the oceans decreases with depth as the influence of surface heating becomes less pronounced. The water in the lower half of all 100 ........................... the oceans is uniformly cold. Originating principally in the Antarctic Ocean, this cold, saline water sinks to the ocean floors and ZONF- OF then spreads along the bott6m toward the equator. Surface tem- NON-SEASC)NAL_ ..... ..... peratures over the continental shelf vary from about 10* C in winter to ____@LDW C-HANCTF-6 14* C in early summer. Surface temperatures decrease during summer upwelling to about 10* C (7). zoo Density he ocean's density depends on three factors-temperature, salinity, and to a lesser degree, pressure (see Figure 31). Temperature and density are inversely related; that is, a change in temperature produces the opposite effect on density. Salinity and density, on the other hand, are directly related; that is, an increase in .1100- salinity produces an increase in density. Pressure becomes a factor only .................. in very deep parts of the ocean; if the temperature is kept constant, an increase in pressure will cause an increase in seawater density. A li6er HUYER-, 11776 Variations in the density of seawater are partly responsible for keeping .. ...... ..... ... the ocean's currents in motion. In the ocean, water generally forms layers Figure 31. Vertical Structure of Pacific Northwest Ocean of increasing density with depth. Where density layers are well devel- oped and stable, as in the open ocean, vertical circulation is inhibited; in Atmospheric influences lead to short-term changes in the upper Salinity (middle): During both summer and winter, salinity is rela- nearshore coastal waters, energy supplied by the wind can disturb the layers of the ocean. The depth of the surface layer changes tively low and uniform in the seasonal layer (upper 100 meters) but stratification enough to bring deeper, denser water to the surface. seasonally depending on surface inputs. Zones of rapid change increases with depth in the permanent halocline-a zone beyond buffer the more stable deeper waters from the dynamic upper layer: the reach of seasonal influence; Temperature (left): In the seasonal layer, a temperature high at the Density (right): Density reflects salinity and temperature changes surface (due to solar heating) drops rapidly with depth in summer; both within the seasonal surface layer and below. 024 0CMAH001PRAPHly !5WFACA5 7FMPERAT'UFZ - 51UMI-n, SURFACE 7EMP6FATZ4KE-W1NTM --1UFAAC-r- @ADNrry-wINTM r_F_N5/TY_sVrv" T= _:@ 7- @UPFAn-_ MN5t wNTE*_ --414F.1 @Ul D@1- Ae, Figure 32. Sea Surface Temperatures Figure 33. Sea Surface Salinity Figure 34. Sea Surface Density Mean annual temperature variations at the surface of the Pacific The salinity of the surface layers off the Pacific Northwest reflects Density is a result of temperature and salinity. Summer surface Ocean are relatively small. Because of the sun's seasonal effect, the the freshwater inflow from the Columbia River. In summer a lower density is clearly influenced by the large freshwater flow from the mean summer temperature is 14' C while the mean winter tem- salinity plume spreads southwest. Its shoreward boundary may be Columbia River over a broad area and by the upwelling of cold, perature is 9' C. Summer upwelling brings colder, deeper waters to pushed to sea by colder, highly saline, upwelled water. In winter, saline waters along the coastline. Likewise in winter the freshwater the surface along the central and south coast shoreline and the Columbia River discharge creates a band of lower-salinity water discharges from the Columbia and other coastal rivers result in a supresses the normally high summer surface temperatures. During along the coastline from Tillamook to the Strait of Juan de Fuca. band of less dense water along the northern Oregon and Wash- the summer, the warmer Columbia River waters are pushed sea- ington coastlines. ward. Vertical Structure Horizontal Structure ceanographic regions throughout the world vary in salinity and ff the Pacific Northwest coast, surface water properties temperature as a result of particular combinations of heating, change over horizontal distance depending on the season of cooling, evaporation, and precipitation (22). A unique set of the year. The Columbia River has a significant impact on the these environmental conditions occurs in an area of the makeup of the Pacific Ocean (see Figures 32, 33, and 34). northeast Pacific Ocean, referred to as the Subarctic Region, and gives Because the Columbia River drains an area of 662,000 square kilometers the waters of the eastern North Pacific a distinctive vertical structure (13), its freshwater outpouring creates a sizeable plume of low-salinity (see Figure 31). The upper layer is influenced by seasonal temperature water that differs markedly from the more saline ocean waters farther to and salinity fluctuations (13). In winter, precipitation, coastal runoff, and the west. This plume migrates seasonally in response to local winds. In storm conditions produce a thick (75- to 100-meter) layer of low- summer it forms a broad tongue of low-salinity (32.5 o/oo) water widely temperature, low-salinity water. In summer, heating of surface waters spread to the south; its inner edge may be pushed seaward by cold, and less intense wind conditions create a much shallower, warmer, saline water during periods of upwelling (see Figure 33). In winter this surface layer. However, the salinity content of this summer surface layer plume is driven by the Davidson Current and storm winds along the is reduced by the large volume of fresh water from the Columbia River northern Oregon and Washington shoreline (see Figure 33). (13). Coastal upwelling also creates a marked difference in horizontal struc- Below the influences of seasonal temperature and salinity fluctuations ture. Cold, nutrient-rich, high-salinity water rises to the surface along the lies a middle zone where salinity and density increase rapidly with depth coast during the late spring, summer, and fall, displacing warmer, but where temperature remains relatively uniform. The greater density of nutrient-poor, lower-salinity surface water offshore (see Figure 32). this layer acts as a barrier to low-density surface water which cannot readily move down through it. In the third and deepest layer little change occurs; temperature slowly decreases and salinity slowly increases with increasing depth. Figure 35. Turbidity Layers Coastal erosion and river discharge add fine particles to the inner shelf, and surface waves, particularly in winter, stir bottom sediments, thus creating three turbid layers over the continental shelf. Wave action suspends fine particles and prevents them from settling to the bottom. In deeper water, waves reach bottom infrequently, allowing mud layers to accumulate. Turbidity, Nutrients, and Dissolved Gases Turbidity, nurtients, and dissolved gases are also important physical attributes of coastal waters, particularly as they affect biological productivity. The concentration of these properties may change vertically from the surface to deeper water and they may change horizontally along the coast and with distance from shore. Turbidity is an expression of fine particle concentration in the water column. Three turbid layers have been identified in the coastal waters off Oregon (see Figure 35)(also see in Chapter Two, "Sediments of the Continental Shelf"). The upper layer consists of organic and inorganic material originating from coastal rivers, especially the Columbia River, and from material suspended by wave action in the surf zone. Organic solids include excreted waste particles, the minute hard parts of microscopic organisms, and other plant or animal debris. Inorganic solids range from molecule-sized clay particles to larger particles of dist and silt (5). Away from the influence of plant growth. The midwater layer extends to a depth where a rapid increase in density prevents continued settling of material from the water above. This material consists of ultrafine particles derived from living things (called biogenous sediment) and from the earth, such as sand, silt, and clat (called terrigenous sediment) (4). Material in the bottom turbid layer may originate in the surf zone but may also result from rippling of the bottom by wave action and resuspension of sediments by bottom currents (11). Between these layers, the water is quite clear. 32 OCEANOGRAPHY Figure 36. Nitrate Distribution Inorganic nitrogen (nitrate) is the one nutrient usually in shortest supply off Oregon. A continual supply is essential for biological productivity. Winter discharges from the Columbia River and Juan de Fuca Strait show strong nitrogen input, but by late spring increasing biological productivity has significantly depleted available nitrates. Summer upwelling is the principal means of resupplying nitrogen to surface waters within a relatively narrow band along the coastline. Off Oregon, nutrient building blocks such as carbon, nitrate (see Figures 36,37), phosphate, and silicate ae introduced into coastal waters from three major sources (1). First, the slowly circulating waters of the northeast Pacific Ocean bring in a low but steady supply of nutrients. In the late spring, summer, and early fall, the Columbia River adds an important seasonal nutrient pulse (1) with high levels of slilicate, moderate amounts of nitrogen, and phosphate levels comparable to those in the incoming ocean currents. Perhaps the most important source of nutrients is the highly saline upwelled water which brings nitrogen, phosphates, and silicates to surface layers during the summer months (see Figure 38)(12). A steady supply of nutrients in the water is a critical factor in the ocean's biological production. If there were not a steady inflow of nutrients to the sunlit surface layer, those nutrients already present would be consumed and further productivity would be severely limited. Figure 37. Sea Surface Oxygen Oxygen is exchanged between the air and the ocean and is generated by plant growth within the sunlit waters of the ocean. In summer, upwelling brings nutrient-rich waters to the surface along the coast and promotes rapid plant growth. Thus, oxygen produced by plant photosynthesis masks the otherwise oxygen-poor nature of the upwelled water. Winter oxygen levels are influenced by wind mixing and precipitation at the surface of the water. Weather patterns affect the seasonal distribution and amount of nutrients available over the continental shelf area. In winter, moderate, uniform concentrations of nitrogen are present off much of the Oregon coast (see Figure 36), but low light levels and low temperatures result in diminished biological productivity. Increased light, temperature, and nutrient supplies in spring stimulate plant growth. Nitrates and phosphates are reduced at the surface, which leads to a lull in productivity prior to the onset of upwelling. In summer and fall, upwelling brings an abundance of nutrients from deeper waters to the surface along the coast, enabling high levels of plant growth (see figure 36,38). TIDES n the open coast, tides determine animal and plant distribu- tion in the intertidal area and contribute to coastal erosion, especially during winter when high tides and storms com- WOKF- UP @N Affm UPWFA-LArAer bine to tug at the shore. Tides are also of fundamental M, importance to estuarine circulation and to the animals of the open ocean which depend upon the estuary as nursery or feeding grounds. In this way, tides contribute to the productivity of the entire marine environment. 0-6- 6-10 /0-zo _-3o NI'MATE -@@/Y5; Mr-WCrV01 Ara-ft, AE@ Tides, the regular rise and fall of sea level, are caused by the AF6-- A711-Ae,@A6,/,-77 gravitational pull on the earth by the moon and sun. The moon, though smaller than the sun, exerts a stronger pull because it is so much Figure 38. Vertical Nitrate Distribution closer to the earth. Its force is more than twice that of the sun. The 1VO"TI-fLY 7%ZtAL P,-@7-HIV5 O@ 7-H,- 0,P49,0'y COAST A comparison of the vertical distribution of nitrates immediately gravitational attraction of the moon pulls ocean water nearest it away before and several days after an upwelling event shows a sharp from the earth and at the same time pulls the earth away from the increase in nitrate levels in the surface layer. Upwelling is funda- water farthest away. Two equal tidal bulges result on opposite sides of mental to biological productivity along the Oregon coast. the earth (see Figure 39). Lead by the moon's orbit about the earth, the tidal bulges move across the ocean as a long-period wave. A particular location on the earth will 0- come under the influence of the moon each 24 hours and 50 minutes, .Y Alfl@111 Seawater also contains a number of dissolved gases which enter the slightly longer than one day. Since the moon's orbit is offset from the .. ... .. ... -sea interface or which are earth's equator by approximately 23.5 degrees, the Oregon coast generated during ocean across the air biological processes. The major gases are oxygen, nitrogen, and carbon experiences a procession of unequal tides spaced approximately six dioxide. Gas bubbles are formed by breaking waves and the impact of hours apart. These tides move northward up the coast; Coos Bay has raindrops and are important in two ways. They transfer gases from the high and low tides approximately 20 to 30 minutes earlier than those air to the ocean and back again, and they carry minute salt particles, on the Columbia River (13). Each day there is a higher high tide, then a trapped within bubbles, into the atmosphere where they act as nuclei for lowest low tide, then a lower high tide, and finally a higher low tide water condensation and precipitation (2). before returning to another higher high tide. Oxygen concentrations are an important measure of the health of When the sun and the moon are in line with the earth, as at a new and nearshore waters, especially where circulation is sluggish. Oxygen is full moon, their combined effect produces larger than normal, or generated in coastal waters as a product of photosynthesis (plants spring, tides. When the sun, moon, and earth are at right angles, as at Figure 39. Tidal Rhythms on the Oregon Coast convert the sun's energy to living material through photosynthesis) and the first and third quarter moons, their forces counteract each other, is introduced through exchange with the atmosphere. These processes, and smaller tidal ranges, or neap, tides result. The earth is also closest A monthly progression of high tides and low tides at Coos Bay as well as the mixing of water masses, control the distribution of oxygen to the sun during December, producing the highest tides of the year. illustrates daily and monthly fluctuations in tide heights. The Earth (see Figure 37). In summer, upwelling brings nutrient-rich but oxygen- Tides produce minor coastal currents, but these are usually weak and rotates daily beneath tidal bulges, but the tilt of the Earth's axis results in a higher high tide at (A), a lower low tide at (B), and lower depleted waters to the surface, where prolific plant growth returns masked by nontidal currents in the open ocean. Tidal velocities high tide at (C), and a higher low tide (hidden) before returning to oxygen to the water. Wind and waves mix the water column and increase increase, however, when the tide moves through constricted channels (A). The Moon's orbit around the Earth brings it in and out of line the depth of oxygen penetration. like the mouths of coastal estuaries. with the sun. REFERENCES Additional Reading *Anikouchine, W. A., and R. W. Sternberg. 1973. The World Ocean. Prentice-Hall, Inc., Note: References are cited in text by number. References marked with an asterisk (*) are Englewood Cliffs, New Jersey. recommended because they are comprehensive, easily understood, and accessible. *Carefoot, T. 1977. Pacific Seashores; A Guide to Intertidal Ecology. J. J. Douglas Ltd, 1. Atlas, E. L., L. 1. Gordon, and R. D. Tomlinson. 1977. Chemical Characteristics of Pacific Vancouver, B. C. Northwestern Coastal Waters- Nutrients, Salinities, Seasonal Fluctuations. Pages Downing, J. 1983, The Coast of Puget Sound. Washington Sea Grant, University of 57-79 in R. Kraus, editor. The Marine Plant Biomass of the Pacific Northwest Coast. Washington, Seattle, Washington. Oregon State University Press, Corvallis, Oregon. *Kennett, J. 1982. Marine Geology. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 2. *Gross, M. G.. 1972. Oceanography: A View of the Earth. Prentice-Hall, Inc., Englewood Knauss, J. A. 1978. Introduction to Physical Oceanography. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Cliffs, ew Jersey. 3. Halpern, D., R. L. Smith, and D. K. Reed. 1978. On the California Undercurrent over the Komar, P. D. 1976. Beach Processes and Sedimentation. Prentice hall, Inc., Englewood Continental Slope off Oregon. Journal of Geophysical Research 83(C3):1366-1372. Cliffs, New Jersey. 4. Hartlett, J. C. 1972. Sediment Transport on the Northern Oregon Continental Shelf. *Scientific American Magazine. 1977. Ocean Science. W. H. Freeman and Company, San Ph.D. Thesis, Oregon State University, Corvallis, Oregon. Francisco, California. 5. Horne, R. A. 1969. Marine Chemistry. John Wiley and Sons, New York, New York. Wooster, W. S., and J. L. Reid. 1963. Eastern Boundary Currents. Pages 253-280 in M. N. 6. Huyer, A., R. D. Pillsbury, and R. L. Smith. 1975. Seasonal Variation of the Alongshore Hill, editor. The Sea, Vol. 11, Interscience, New York, New York. Velocity Field over the Continental Shelf off Oregon, Limnology and Oceanography *Wright, R. W. 1976. Currents of the Sea. Natural History 85(7):31-37. 20(l):90-95. 7. Huyer, A., and R. L. Smith. 1978. Physical Characteristics of Pacific Northwestern Coastal Waters. Pages 37-55 in R. Krauss, editor. The Marine Plant Biomass of the Pacific Northwest Coast. Oregon State University Press, Corvallis, Oregon. 8. Huyer, A. 1983. Coastal Upwelling in the California Current System. Prog. Oceanogra- phy 12:259-284. 9. Huyer, A., and R. L. Smith, 1963. Pacific Northwest: Physical Oceanography of Continental Shelves. Review of Geophysics and Space Physics 21(5):1155-1157. 10. Huyer, A., and R. L. Smith. In Press. The Signature of El Nino off Oregon, 1982-83. Journal of Geophysical Research. 11. Kulm, L. D. 1978. Coastal Morphology and Geology of the Ocean Bottom-The Oregon Region. Pages 9-34 in R. Krauss, editor. The Marine Plant Biomass of the Pacific Northwest Coast. Oregon State University Press, Corvallis, Oregon. 12. *Oceanographic Institute of Washington. 1977. A Summary of Knowledge of the Oregon and Washington Coastal Zone and Offshore Areas, Volume I. Oceanographic Institute of Washington, Seattle, Washington. 13. *Proctor, C, M. et al. 1980. An Ecological Characterization of the Pacific Northwest Coastal Region. Five Volumes, U. S. Fish and Wildlife Service, Biological Services Program, FWS/OBS-79/11-79/15. 14. Pruter, A. T., and D. L. Alverson, editors. 1972. The Columbia River Estuary and Adjacent Waters: A Bioenvironmental Survey. University of Washington Press, Seattle, Washington. 15. Ryther, J. H. 1969. Photosynthesis and Fish Production in the Sea. Science 166:72-76. (See also letters in Science 168:503-505. 16. Simpson, J., and C. Koblinski. 1982. New Ocean Eddies Found off California. Science 215:1490. 17. Smith, R. L. 1981. A Comparison of the Structure and Variability of the Flow Field in Three Coastal Upwelling Regions: Oregon, Northwest Africa, and Peru. In F. A. Richards, editor. Coastal Upwelling. Gordon and Breach Science Put5lishers, New York, New York. 18. Smith, R. L. 1983a. Physical Feature of Coastal Upwelling Systems. Sea Grant Publication WSG 83-2, University of Washington, Seattle, Washington. 19. Smith, R. L. 1983b. Circulation Patterns in Upwelling Regimes. Pages 13-35 in Suess and Theide, editors. Coastal Upwelling, Part A. Plenum Publishing Corp. 20. Stevens, P. R. 1983. Seas From Space. Oceans, March, 1983. 21. *Thornson, R. E. 1981. Oceanography of the British Columbia Coast. Canadian Special Publication of Fisheries and Aquatic Sciences 56, Department of Fisheries and Oceans, Sidney, British Columbia, 22. Tully, J. P. 1964. Oceanographic Regions and Assessment of Temperature Structure in the Seasonal Zone of the North Pacific Ocean. Journal of the Fisheries Research Board of Canada 21(5):941-970. CHAPTER FOUR [PL&MMU(OH The Drifters enough to create a "red tide" (so called because of the color imparted to the water by the explosive growth of these organisms), they will be consumed in huge quantities by mussels. Toxins from the dinoflagellates can be stored in mussel tissue, often to the point that the mussels become extremely poisonous to humans who eat them. As a result, mussels are occasionally put off limits for human consumption. In addition to studying diatoms and dinoflagellates, marine scientists recently began to appreciate the importance and wide distribution of the INTRODUCTION icroflagellates. Somewhat neglected over the years, these micro- m lankton are free-floating plants and animals of the sea having scopic plants are so small that they are difficult to sample and analyze. little or no ability to resist the current. Often transparent and Scientists now use closeable bottles rather than nets in an attempt to quite small, they are not the most noticeable organisms in the capture and study these small organisms (20). sea though they are certainly some of the most important. Phytoplankton, simple single-celled plants, form the base of the pelagic food chain. These inconspicuous marine plants also produce 95 percent of the sea's oxygen, an element necessary to sustain all living creatures. Millions of years ago, plankton settled to the bottom of shallow coastal seas, where they were buried and subsequently compressed, forming IREPRE,5ENTATIVE_ D14MM-5 Phytoplankton Production the oil and gas deposits tapped today. Zooplankton, small free-floating etermining the amount of organic material produced by marine animals, range in size from ultraminute organisms to large jellyfish. More IYO T_ A LL_ DI?AWN M -54ME -SC-4 L-6 plants is important in assessing the amount of food ultimately complex than phytoplankton, these tiny animals convert plant material to I available to support the marine food web. Phytoplankton animal tissue and provide the vital link between phytoplankton, the ID) abundance in the ocean varies, depending on location, sea- primary producers, and the rest of the ocean food web. son, and even time of day. These variations are measured in two ways: by standing crop, which is the number or weight of individuals present at any one time (a static quality), and by productivity, which is the rate at PHYTOPLANKTON which these microscopic plants convert nutrients and carbon dioxide into new plant tissue using light energy from the sun (a dynamic quality). s on land, photosynthetic plants growing in the sea are the basis for most forms of life, converting the energy of sunlight Since plants are the first step in converting the sun's energy to an into organic materials such as sugars, starches, fats, and organic form, they are called primary producers. Biomass, or primary proteins, which are then used by a vast array of marine production, can be measured by sampling a known volume of seawater, animals. To synthesize these basic building blocks, phytoplankton allowing the plankton to settle, and then either drying and weighing the require nutrients: nitrogen, most common in the sea combined with sample or burning it and estimating the amount of organic matter from oxygen as nitrate; phosphorous, present as phosphate; carbon, the amount of carbon dioxide driven off. Problems in separating live from potassium, sodium, calcium, and sulfur, all plentiful in the sea; trace dead material and in distinguishing plant from animal species prompted metals; and vitamins. development of a second technique. The green pigment in plant cells, Photosynthesis requires that phytoplankton remain at the surface in the chlorophyll, is the link between the sun and virtually all life. Measurement sunlit waters of the euphotic zone. Lacking their own means of mobility, of the amount of chlorophyll a (one of several types of cholophyll) can phytoplankton have adapted special means of remaining afloat. Small- give an accurate count of plant production. ness increases their resistance to sinking and facilitates the diffusion of P2SDRE-5EJVTAT1VE_ 1D1A10,FLACTf:LLA7_E,5 Phytoplankton productivity is controlled by several factors-light and nutrients into their cells. Some form chains or grow ornate appendages IYOT-AL.Z-DRAWN 7-0 _S4Mt_E nutrient availability, temperature, mixing, and herbivore grazing. Light like wings or spines which help to keep them at the surface. In addition, and nutrients are essential; without them photosynthesis cannot take surface-mixing processes of wind, waves, and currents assist in keeping place. Temperature influences the rate at which metabolic processes these tiny plants within the euphotic zone. proceed; photosynthesis and, in turn, respiration (which consumes the Plant plankton fall into two size classes: the nannoplankton, those that Figure 40. Phytoplankton of the Oregon Coast products of photosynthesis-oxygen and sugar) proceed more rapidly are too small to be captured in a fine net, and the net plankton, plankton Phytoplankton off the Oregon coast vary in size and shape. The at higher temperatures than at lower ones. Mixing keeps phytoplankton large enough to be sieved and captured in a net. Phytoplankton can also diatoms and dinoflagellates shown here are typical examples. They suspended at the surface, but if too virgorous, forces them below the be classified by locomotion: some have whiplike swimming appendages are not a// drawn to the same scale. euphotic zone. Nutrients are also brought within the reach of phy- called flagella, whereas others are true free-floaters. Although many toplankton by mixing and other circulation processes. Herbivores graze different groups make up the phytoplankton, two are particularly impor- on phytoplankton, reducing their number, but may also be important in supplying nitrogen through excretion, which in turn can have a positive tant in coastal waters: diatoms and dinoflagellates (see Figure 40). valves are secreted, and the parent ceases to exist. Simple cell division effect on phytoplankton populations. Diatoms are widely assumed to be the most common plants in the sea. accounts for the rapid growth in phytoplankton. Dividing once a day, a In the temperate waters off Oregon, two factors are particularly critical: They have an external shell composed of glasslike silica (see Figure 41). single cell can produce a billion copies of itself in a month (20). light intensity and nutrient concentrations. Light intensity varies daily When diatoms die and fall to the ocean floor, they become a major Dinoflagellates are a diverse group; some are plants, some are animals, and seasonally with cloud cover, day length, and sun angle. Moreover, constituent of marine sediments, especially in higher latitudes (20). some have an external cell wall of cellulose (hence the prefix dino: turbid waters can significantly decrease the depth of sunlight penetra- Each shell has two valves which fit together much like a pill box. A .,armored"), and some are naked. The presence of toxins distinguishes tion into the surface waters, thereby decreasing the zone in which light is diatom can reproduce both sexually and asexually by simple cell others of the group. Mussels along the Oregon coast feed on phy- sufficient to support plant growth. division. When a diatom divides, the two valves separate, new opposing toplankton, including dinoflagellates. If clinoflagellates are abundant [PLIMY17(om Kt3 7 XX.: A N . ...... .......... .......... ................. . . ............. ..........- .............. .. . . . ...... ................ .............. ............... ................ .............. ............ Figure 41. Electron Micrographs of Phytoplankton .............. A. Phtographs made with the powerful scanning electron microscope reveals the shape, structure, and surface texture of diatoms. On the ............. left, diatoms on eel grass are shown 1000 times life size (photograph by Michael Eng). On the right, diatoms on a squid are shown 1600 1Z,0Y4Z57-ee5 times larger than life (photograph by Carla Stehr). These photographs, called electron micrographs, were made at the Electron 171c, eK) 16? 0 Microscopy Unit, National Marine Fisheries Service Northwest and Alaska Fisheries Center in Seattle, Washington, and are courtesy of Carla Stehr. ........... ............. Of the many nutrients needed by plants to grow, inorganic nitrogen is ................ ............... the one which is usually in shortest supply, It is therefore a limiting factor which may place a ceiling on plant growth. As phytoplankton grow, ........... inorganic nitrogen is removed from the surrounding water. To sustain ........ .. growth, nitrogen and other nutrients must be continually supplied to the The onset of upwelling replenishes the surface waters with nutrients euphotic zone. The most important mechanism for replenishing depleted by spring phytoplankton growth. Phytoplankton populations . ......... inorganic nitrogen to the euphotic zone is upwelling (see "Oceanogra- respond to increased nutrient availability by producing outbursts of ........... phy: The Water"). Dead and decaying matter (detritus), fecal pellets, growth called blooms. Phytoplankton growth and subsequent grazing and dissolved waste products drift down through the water column and by herbivores again reduce nutrient levels, and by fall, shortening day .................... . ......I........... ............ .......... ................... .......... . ..... are eventually remineralized by marine bacteria into a form that can be length and colder temperatures set in. Periodic upwelling events at this .......... ............. used once again by the phytoplankton. time of year, however, can lead to small increases in phytoplankton. The Affer @WAL,1_ and highest concentrations of phytoplankton during an upwelling event are ......... Upwelling areas, like the coast of Oregon, are regions of high production ........... ..................... as compared to the open ocean (18). Annual primary production on the often found in bands lying parallel to the coast. The position of the bands Oregon continental shelf is typical of that found in many other upwelling depends on the intensity of upwelling and the width of the continental locations, with values ranging between 200 and 300 grams of carbon per shelf (see Figure 42). Figure 42. Phytoplankton Concentrations over the square meter (2, 22). In waters west of the shelf, total yearly production Few studies have been made of Oregon's phytoplankton populations has been estimated to be 125 grams of carbon per square meter, a value west of the continental shelf. However, the species composition of Continental Shelf considered typical of temperate oceanic regions (2, 17, 18). phytoplankton in oceanic waters differs from that of the coastal zone and Samples taken along two transects over the Oregon continental Nearshore phytoplankton growth is closely tied to seasonal fluctuations. diatoms are much less important as primary producers. Phytoplankton shelf near Newport show phytoplankton concentrations per square During the winter, surface wind-driven mixing produces sufficient abundance offshore is much lower than in coastal waters and, rather meter to be twice as great over the narrow shelf (rransect A) as over nutrients, but light and temperature levels are too low for plant growth. than being concentrated in the upper 20 meters as in coastal waters, the wider shelf (Transect B), but total abundance is approximately Mixing disperses many plant cells below the euphotic zone. In spring, reaches a maximum during the summer around the seasonal pycnocline the same. however, nutrients remaining from the winter are present at the surface, at 60 meters (2). Because many phytoplankton species are adapted to and phytoplankton growth increases as the days lengthen and tem- certain light intensities, a chlorophyll layer at this depth may indicate an peratures warm. assemblage of diatoms able to 'photosynthesize in the presence of adequate nutrients at much lower light intensities than at the surface (2). no (D FuHnom _V IIMill Figure 44. Electron Micrographs of Zooplankton Zooplankton, while typically much larger than phytoplankton, are none-the-less very tiny. The scanning electron microscope gives @UF@AUS- marine scientists a valuable look at surface details which aids in understanding how organisms develop at an early stage. On the left, a IN newly hatched squid, shown 50 times life size, displays many of the features of an adult, including tiny suckers on its not-yet-developed tentacles (photograph by Carla Stehr). At right, a marine amphipod, Rhepoxynius abronius, is magnified 40 times to reveal a body with segmented plates (photograph by Caron Stehr). (Photographs courtesy of Carla Stehr.) Zooplankton occupy the first few levels of the trophic pyramid above the primary producers (see also Figure 3 in "Marine Ecology: Life and the Figure 43. Zooplankton off the Oregon Coast Environment"). Some are herbivores, grazing on phytoplankton, whereas others are voracious carnivores, preying on other zooplankton. Many different animal groups are represented among zooplankton Eleborate food-gathering mechanisms have evolved to capture the samples taken off the coast of Oregon. These drawings are not ZOOPLANKTON variety of food items consumed by the zooplankton. drawn to the same scale but are arranged from top to bottom by early all groups of marine animals have at least one develop- Although zooplankton are not restricted to the euphotic zone as are increased size. mental stage when they can be considered zooplankton. The marine plankton, many of them live by grazing and must remain in the young of most nekton (animals that can swim) are planktonic, surface waters. However, zooplankton are less affected by sinking, IN] and many benthic organisms release planktonic larvae to the since they have more swimming ability. Many groups of zooplankton water column. That larvae can drift can be both an advantage, as when migrate vertically in the water column, surfacing at night to feed and the larvae of attached bottom-dwelling organisms are dispersed widely spending the daylight hours in the dimly lit water 100 to 200 meters to find suitable environments, and a disadvantage, as when currents below (see Figure 45). carry the young beyond their range of environmental tolerance. Zooplankton are an important link in the marine food web, converting Zooplankton lifestyles are far more varied than those of phytoplankton. plant material to animal tissue. Although the specific food habits of most Zooplankton have developed ways of pursuing and apprehending food. animals off Oregon are unknown, it is likely that most fish and larger Most are multicellular, not unicellular. Reproduction is sexual rather than pelagic invertebrates feed on zooplankton at some time during their life Beyond the shelf, winter mixing increases nutrient concentrations at the asexual, and the advanced zooplankton have more carefully pro- history. Numerous species of fish, including juvenile salmonids, myc- surface. In summer a thin layer of Columbia River plume water (see grammed behavior for bearing young to increase their odds for survival tophids, Pacific herring, and northern anchovy, as well as squid and "Oceanography: The Water") begins to spread over the region, surface (20). shrimp, are known to eat zooplankton (11, 19). waters warm, and the water column stabilizes. Conditions are ready for Many groups make up the zooplankton, including chaetognaths, larva- The pelagic food web is based primarily on grazing, that is, zooplankton phytoplankton production, which then begins to deplete the supply of ceans, ctenophores, medusae, pteropods, amphipods, euphausiids, eating phytoplankton. A large portion of the energy produced by nutrients within the surface layer. Consequently, production decreases and the larval stages of many fish and benthic invertebrates (see Figure phytoplankton flows through the zooplankton to the higher trophic levels throughout the summer. A slight increase in production can occur in fall, 43). Of these groups, the copepods, jellyfish, and euphausiids make up as indicated by a consumer-to-producer biomass which approaches when stratification breaks down because of the onset of surface wind over one-half of the animal biomass of the pelagic habitat; copepods are one-to-one (6). mixing, and nutrients return to the surface (1, 2). the most abundant life form in the waters of this region (6). 0 nQ @ . NOC51111 NIPIY16@HT /Yor,/Y DIEL VERTICAL MIGRATION __ .....;:-.@. __._.................@........ ... __ ".-1:.:1.1:.-. ...I.I....,..... _.@,-:,:: :::** ... ... %%..:-..-.','...',,'.-..- --:1.'..:1.:1 ... :::,.. ......@ ........... :-- -- .., @_.. - _" __ ....... , ... - ___- ..... .:.:...:::@:.:...::",..:.:.....:.:.:. . '@@...::.@:":.::,....-,,.,.,,.,,,.,--.-.. ".. .... .... ;;Za:*$@:iwl..,.@ .. ............... I... 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W,-..:... 11.:,...:.-.....- ........_........ ..... 1. ..--..-..:..:.:.:.:.!.:.:...- .,-11 .., .. .: .;.--. -I-::- - .. .....:::::. - - .,: . .... _:@@r. *.@.. ,::,.*,.*...,::..,.*i.,.:i.,.:..i:@:..i:@:i:i..: .. .:.... @ .. ..........@--... 1. : *4:I:..,..: . ....@-...:,.,*.. - -,...: :: . I: .................'.._ : .., -.,,. .. I@ ..:- ;,, .1 .@r..,, , :.;: " .. @. I..I:.... 1. : @.-II.,- ... . .... @@. -- ... ..,:... . I ......- "r',:..-- . ....... ,-_, -- ...... ., . q: .-".:@X.:::::' '_......... - ..::@. ..--..: :: .@ rr ,,::::.::@x:.::. .'@: . :% ::::., ';@' .:.:.... I..,'.............. . . . ...-I- ". - .. ...,- @.:..', .,-...@...... - ... - . myctophid fish Stenobrachius leucopsarus and the shrimp Sergestes .::::%........:...:,. :.:,@:;:@::..' .: - ..,:@:..... .... -. - .--:.-r..:.-_:@o ..,..1.:.,,*:,:. ___ -r-.::.:.:.:.::.:.::.: 11.I.:_ ....@:.:.:-;.. :- *** .....,....,rI:.. @: -:'..--:r: ' '.:.. r.. :. ::: @::@i::.:, .m. ...@:Ir.I.. -..., ...........-...:.....: : *,.*,.j-.,:::j: ..j.'. ... ;: .... .. %.. ... ................ :,*-..- .: --.:-X--. :....:.:.:.:.:.!.:.:.:.:.:.... :: - ..-::..:..j:j:.-.j:j:r:i..:. -@ .: .:., .. ..,.-:":,-- .@..... ............ I I . . ....:1. r.. _1 ..... ::.@@:@;@@:*7'@' r ..:%. ::. @& @::**-:::::::e,-.@ '..... vk.:_i@:Atl *.:.4=;V,-:::..* .... . ... ... ....::,. I :.q. .......... .1-: I .:-.... -.... .:.: ... 1. @.. .::, ......@r:_I. I ...... ..I......... similis, and typical euphausiids. The movement of individuals to surface .:::::XN.::.:.... .-..::::: :` '',Q---- .. ...@, .. .,.r....._: ,@'.:. ...... "":',.%hrI.... :.: .:' -:. - ......... .. .............. ... , ..:. ..:.II...@: ,,...... ... ,... .., r .@Q@@..:@ .. I::. ***-:::::::::: - : ...:.. .'.*..-..,.':@..::-., r<:::;::::.;@.: ... '. . . ..- @ - - @... I . *-:::::: ..*.. @. .::!, -....:::::,: -- -" ..._W%,@' , ,.::;.:. .., . ..r r. ..:-.,.*..... ,-...rj@j: ::;.@j:.::.:;:, .. . ..... 77@@ ..':-1. ..,...I,..... .1-:-.-'.-:1..::':'::,.:.-r...... ... .:!::::!:@:::::1 .,..... [email protected] .. .. :. ..*-_.-.: :: @:. ....,..... .............. r.. @@:.- @ " ", -@ '[email protected], .:.. .........:*... :1 , ,'.@:.0.V!P @, ::.. .. @:@ . ., ............,.... :: - " - - Aw .:[email protected], -I., : . .... * ,-,.."...".1.1 ....:. ...,-... r.. .- -.......@ .::.:.,1@@ ....I.1, "i .. .:.% .....::::, I ...... ---.. ...I. . .. . X.... ..1@_- . @ -@ .". - .. ...i ... - [email protected] @ i -. ..@. ...@ r- @.I -:- ,@.*@;.....111111 ...... @: ...! @ @ -@:::@!@@7,, @:i:@4.. ... F] ... V: ... '...'.....,.. . @... ::..::- .:.. :. , .., s @. @@ ...] ..... ... .. . 11:-...:- .e. .: :. ... - --- .1 .: waters at night is readily apparent. -:--,....-,. ........ .. .. I ...... ..@... ': -I... 1: .......... -.1-1 ....,....@.,,...,.....@ ......... ,_,_... ...I.- %N.I...."......... .,.......- ..... ... @@ ... . ...: ,...... .*........,-.....@...@..: .. .... .-- : . ...., ... ...........-.,.:@t@@ 14.0 .; @ .:::,- @... _...... .--.... . ..... ....r.,"':...-..I%. '.? 4;@WI...... . . ._ ,.. . . ...,.. . . . . .::!, : X., ..... 1--.1--1:-.-'1:-:-::-: : -@ .-rr :.".,, .... ..- ..@.... ..-..: ..-.,. .r r. '.".r @ @ - ......-....... ..................,I.,- -@r.... @ ...I.....:- .. .. @ . .'--...@... .: . .........-."I.1@:r .. C. -;.. ;,:..'...::@:%@' .... -@:;@ :.--@:' ... .,-::. --- ...I... ::::::: .: .:,:.....:.% . .r @'. r: : ::::::.r.... . I:...... :..-.... @ft*,-...I....... I........ . . . . ...... .: :: %............. . @.,. ,:. : . . I.,,.. .:;:.r%. . ... -, . ...::,:... . .. @: :@ :::r: '0 . .. :::..".,..:.....:,..:,.....:,.....:.:....:..:.@ .... ...,.. .--@:@..@I I@@-.1 . .I'll. 1. ...... ... ,....... : :::. .-r.,I- -r .....r ...I. o'.. . ..... ... ... . ., ..........,..- ,, ,"r" @:_:j....,@ .I%.I.1.1-I -1.%11......... .... ... . .. ., ,r. . ............ '. @:.:@ ...; :..., .1. @.I ,@@.-.. .. @:@:. :@ :::. ,; i,: . .,..:........... I ...... @ . ,.I-. .--.I r. ... ....-. .. __ .: ..... I... @ III ::@:@ -'. '.`@:-,., .,.:,.,-@:,.N, .1:.- :. ,.. .@ .-. .I..--@ .I: : : :r.. .. .1.-A . : ... @...:': 7 . ... @.Xl@ : :............... ..r..:::-i'4.., :.. @@..:.. P1.-.'-.`-'-'@ Few generalizations can be made concerning the relationships between . .:. ' r::,';::::@ ' ::..: r. r ..,.AA@_ :., :..'.1 ."'.,@.,..,:,.,@.,.,:@:@.".:@'.. ...!@. .: :I ...'4!;@W': ,r:@ W..--@::@; .r @.j.._, .@. ;@*k, @ios -,.,,., If.,-.r:, :::@,j:@ @:.@::@@-::!@:@: . . .r. :::;..: @'-:-: ........ .......: ... .........., ........ ...:...... . ,.-. ,-.....'r.. ::..; .::; -.-:- j.; :.*: . .::::.:* ::':-::::.:::.:.:@. ,I I..,._. ,' ' r _'. .' ','.'...... ,' .::*.:; ::r .I... @ ..:.,: : N. - @r 1.-.-'.:::. @:@:@:@:@@]::@@@@;@.'k.::..e.: !;@: .1; :@: @. '.. ... -:::%:::@:']-@I . . . . -s:;: -. : : .r..... ... --..:.., . ... ,:. .:. .w,. ..:: ,Id" :. ..@ @..... ...:: . :; ,-. .,: : . : . :I... .:,; 'i :- -@:@,I r:. ..*.:. -, ....... .. . @, *:1.0F.r.',' . .:: . :1. :1@ ... @ @ .i .,"* .. :@:r.:@i - :@: ..@ ..... . ,@ .: .r -::'. .,..r-"..: ...N.... :::, ,-Ar @@::@--'....' ...I - .s. o:,: @ i:i@ii ,: .. ,I_.,:::j;.j. , ,e.``@'. , "-::::;:::: ..........I. .. ..@. ....:.. !-.@.._ . .1 @ .@. 10. r;;... .. -4 -'r.1...:.:. N.. @ I.I.::;. " r, species which migrate and those which do not. Both herbivores and ::*..., @..A",-I-'.@Aii .,:@.@..@ ..., .6', ., ..,..... - " ...%- .1 _::@-r..:.r @@4 :: ,:,%.,,,...",:@]@@@i@@@i@@@iiiii:i@i@i:::.i@: -.I. ..... r, r r ...'e@r..::.: ...'.. .-..:-:!1. .: ...... ....r..a... . *..4 -*:@@::, - : 'r'l . .:. - r . 1.1 ] :'e..., , ,, , e. .i,: :i ': ", @:.*.@. . 'a. ".1 ..... ........ ... ...,.,.,......,. :,.@ -i` ,. .:,@ .:;. ...IA' - .-__ . .:: :.. -.:1 : @ .:_;., .. .: @.. , :@:., _:;: .. .......- ....::.::@@::, -.:.: . .... ....,.... ::@:@:@:@ @::...:. . :1; = : .. : :.,*:-.-: X :-!1,:-,`.-: : : :,.,A .''. .. .., .... `....... .--,. I, @r%'.. .. . .............@NO ..@...@ '... 1. ..-@. .:,::.. .'-.-@'...:.@ :@:r-!:@-*- '. ':. : :,. e:..::.,.......,..... ......@.......@.@..@'............... .:4 *, .......7- ,... ...... 11.'. I...." ......................,. :., :.% -.@-.. .. @... . r r.r -....._,-e: .*.-.@::@...:..'r @ ._.... .. -.. *@@-. 4e., ,:,::, "s, ... @.'. .. ........ carnivores demonstrate migratory behavior. Within any one animal group @@@@:@:@:@:@:@:@:@@@@@@@@@@@@@@@]@@@:@@@@,-10",. .-... I-- ,!:r:'f'..,e.,. ,,::@@. r'.,.. ,. ._-__,.-..,..?P_S ._::..;:---.,%@, . r.... ... @-...r .---. :i:@:... @@;:is:jj::i::.@:.@.!@@.::.; .-*'..,'.. - ..: ...... .@ T: --': .::':. r @.... ..::::i-:@ - ,,:;:: @@. .: . '' --.,..... tw,:.. -:-:-:-'.--. :: " ....::..::.::: ::: .. -..1.-...@@. . ":r !.1 "'...... @......: , - W....,.........:., ....... ,:.:. _;@@:,..... .. ...... ....., ... .. :: -:.10::.::,.:::-.@- ...@.... ...........%..", .....- ...,.. I @.. 1. I r. @::::: ,....-.., . ......... or within any one genus there is considerable variability in the number of @......--'..'.'.'@@!@j@;@;@:@@@il:@:@;@:@@@@@;@@: @..,:_.'-:-...-.-::..-.1... .1..:.-@ ...:::,.::. 1@@- .@[email protected] .'-_0. ;.,_ : ,......: -.. . ..W.- I:.e:::..j. @... ': Z_.@._..-_.... .. r'a: @.!;:,-".. :,'@,.,,,. @,. :..r . .,;.-... r ... . ...::: .! .:;., .- -:. r I. I II.. .............. @w @.. .-.%... 'j: .... :1: .::..:,@ . . -.. .. .. ..... .., .........: .. @. @::.!_1. ..';@..j,:'."'. ;'.. .II .11.,.@: r.. ,: @..: & .*:-:-::-:-.-:I.-:-,- : ::-I-. ..., ... ." .......a...,.. e., ::I I:r. I ....... %.._,,::,@..@,_ ... @ d.: :,.-,.. @,..,.i::,:.:@.:: @j@:::*:..: 1: ::'.:r..: 1-1I*,.. 'i',, ::@::: :,...... :; __ ,,,.. ............. ::. ..... ..--- -.. ..I.:., -.::. @:- :' :.-..:-., -:-*: : @-- ;; .. .......--::... .. ...... .:.:.:I....::. .. - .:.,:.:.: ... ...: .... I ..,..: .. ..... ... @.@. .. . ...., .. ...:::.... .... -.. ........ ,.,:.:.::..: - .:.::. ..... . .r- ....@@: .:.- . @.- ... ,.r. .. :;:-... - .: @ ..I-;... @'.. :,-':..-. : ,::;@ li@ .:.. .... .:::.. - - ,:i@i@iii@l:.:!:.:::::::: -._ ...... @ .. @.. . . . . .a @.;:-:-:-:-'- ......... . 0 .:: .. @M. - - - --::@:@ @ @@i *@I:.:..... .. .... 0. .1e:...@... ..%... I.@ j......; :.. @.:.... 0. ::::::: -...............'...... . . species which migrate vertically. Even members of the same species ... .:... ...@0--:@:: *-!-@i@ .......""...'.., :r '. @@* ..,.:.. a. @.:..... .- ... r ........, @,r...... [email protected]........ ...,,. I.. ........- .. . ..... ..... ,...1.- ..... @-,.@ -:.- I.:.... , @......... .... :::::::::: @@,@.......@......@.@..........@.... .s...........X........ "'@ @. "'. *::...@, :.. .@:::. :..,. @... .; I. :,.::-:.:: ::.. I-- .. ... .. .::-x. ,,.. .::.:,.:::...:..:.,:.:: .. ..@::,,:'.'. 1:1*:::::: ***@::--.-@."...i. . .1 I.... .. '! -.. . .-:,,.. @:: .:.: . .... % .. 11::@.I-.:: , - *r;,-.. @..,_._ .,..:; @.-.-- .. -:@:: _': .............., may or may not move vertically within the water column -.. ;-......... ., :..I-I @......-:: .--:`:-'. @I: @:1. ..'r' ..:::@ -.-'. ..:...:...:. .......... .... . ....I--.. ,. .."...,- jr-1k, @........ -@;];@: -@i:@i@."@@i@:@:@:@:@@ I---. ........ . ... .1 - 1..:.,. -x.....-.,,, ,.: I ... ! -, ,., .-...'... @.:....,:.@ .: .:,.::::%:?::: .',.,r.....,...-...'..'....., F. ,....,.. .. 1............ - -::.-::@,,- -_. ..:.. @-:-::: ...:,:::: ... --.. ..-; ... .. .... . . @ _......-... 1..... *: ......... -. -... @@ . . . . . . ...........:: .::::::!:,.. . ::.".-, -'.-,*-'"*'* '---......'. . ...._e_ .. -_-@-. ..I.:* @.. .- _...-..r ...... ,...._.__ ........@@:...... . . . . . ...... , ......: I....N. on a daily basis. ;@@., .....,.- ...-- -:.,-.,.,_-., ....,...,.,.;:@:,,.@:::."....,*.: -1% @@,'@.--,.@' ..., r:;:..:..--1111...'@ ...;: @-@. . . . ... P.. . _., . @., , - ..:,. -.1,:........... -, m-::-...... @ r -.....-@ : .::.. . . .-:, @ @....., @... . . .... @: .. [email protected] 1. - 4.%-.. .%....... . ......."..r.".'. .... .. -:,'.: .. .%,:. .:...:.: .. ..............- % ..........:N'... .::....:,.I.,:@::::;:@::::@i@i:-;:::::@@: [email protected]:i@@j:::.,.:.:.: ... - .. .,,.:::..::..:..,@;,:....,..,.r,,......-... .:::.::::::::::,:::.::.:.::, - .:: -.........-. ... _:::::: - I.: *0:.:, .. ..._ -....:..."...1..... -::.:..-.:@-'...".-- !... ...:... _ ._.. .. ........ @-_I... .. - :'...,:..,.,..'..-_.1 _'.'::-_':r-_:.- -;@@,-. .---@.. -i,.-F. ..... .. - ." 1%.......'......1.I....*_. _@:-,-` ... ::@.?R:,... . @-:::: . ........ For example, a portion of the Stenobrachius population fails to migrate to .. -.........:.:............ . ...,* . @.`@,.-.:::::"]@-',..,i:@:, --@'. ... [email protected]. ::::.. .. .,@ r.. I @ @@ : . ....:: .......... .@. . ........ :--,::,. .::::,.:.,:.:.,::.:.: .. 1-. . ... :. ,::.:.,'_.:,_,,,....,,. @::!:...@: .- ..: .: -...::::::.. 0:;@:-.:,.-.,:.:.:...-..'r.. I...,:.::..,., .. ...:. --....- I.. @.. ... @ @:. ...-,..-.,_::",:.:::.:.'.' ...::`-:::.'.-.-.'.'-'- .... ...- W.. . ... .. , @.....:.. .....:.. ........... : , . ., .1 1:-.. ,.. -1 ...'.... ....'r- ..--:--:::-:-,--:-::-::.:: ::::@@@@@@@@i@@:@i@@;@:@:1:1@:@@@@@@@@@@@@@. ',@..:@:i@*::-.. . @.-!.,... @@::.*'...:::_4 .::@. @,-:,.:.:,::. ,.:.: ,: _:@::::@@:. . ..........I.........I:...-. ...... :. r..-I.:-.: .. ..._ ... ... 11 .... :. - .1 .. . .........:1 ...,r ... :.._.....'r....... .. .@ .... --- ........... r....-..:. , --:@i:.; *:- "':* -....-- .......... ..- _P.r. ,.....:... - ... .-XI.N. :.. - .: @:-:-:, ,,...- ..'#r---::_: , .,'* __ ... @@... the surface at night. Those which do not migrate remain below 400 .. -... .-- -.@., .''.--I 11 11 11';-.... .. @ @.. :... . ,.:.: ....... I.- .::::i:i!:@:@@:@:@:@i:.,@ :-:.:..::-.1.-:-:-:-:::1.1.-:- @ `::"-.::- ........ %. @ I...-'..:..: - -... .,..:.;.;: -% :.'...-1....,....- %.-.. ..",--- -- -... .@[email protected] . :1.::,:-.:1._:...-:-;; ........... .''j@@' '.. .:,.*..-..... ..'.:r.- -... '.-j-*.. ..: .. 1: @'-`@r"@: @*@. @.. .1. @:::::::-..... "......: ........@ -@ ..:*;'.'`'!."@j:@j@j,:.:, r _- , ... ,@'.@.. @:..@'.:: ... ::.:"-@::.:: .....%..: .. ,@.-.. .... !.....::. : :.@::: :.:,!-..:.::,..:.:,...::..:: -... ... - r ....I.@::, "',1,......r...... %--..4.:::,.:,.`.,@1: 1:, :.. _..:..-:,,::.:. . .1 ... ;r.:.::.. ,:.@, ..._., .-..1. .: %- ...-.... ..... .@. ........ -.1 ::':'!.:.-.- .. N. :::......- .:::!, -:,.".. i:i@j:@@:@j@;@:@@@:@i::::@@@@]@@@@@@@@@@@; .::..:.e_ :.-,: .@:' I.....-e.,.. ...I-...-- @:,.:- :::::,:::::..:; .;: .. .. A. -:-!::-:.::@.-'.-::-:1- , .-@:%: ':@*:...,._!. --... 1; @ .1. ... 1:11.. . ....". .. I:.:,r'..' ...P __....'. .::: .:..". .: - :. 1: @i@:@i@@@@@@@@@@@@@@@@i@@@@@i@i@@@@:@:@:i: :.::'':. :: .. .:,.: _........,'.r.1..--. @. ...... . .'.'.'r .... ,..... .., -. ... , ... .:17:%.:::,. ....:.. -::Xi@..: ..., -m::.:@,.:@.;. :::: ... I.....; meters after sunset. .-,.@. ::.r...:-- @ ....1.1 ...@ .- "... @..X.:::....,.-.- ... . @.: .'.:.'.1..:-%r.... ....'. r -.........- Ir .. :1'.:.1:-. @:., .............. ,,..., - .", . ..... .. . ...... .- ...... -- . -. ..::@...-. ...... .. .. .--@*-,.-*@ ....,::*:.. I - ......, .." .. r.@:-::m,--.:@i@-',: -@."i...@`.`-, .-- - - I-. . .. ,._.1. .%. , .........,- ,.I............. _... I..". . :... - I.. ,:A@@ :!.:....:.::.::,.::.::::::...,:I @i@@@:@@i:i:@@@:@:i@j:@@;@;@@];@;@:]@:::;: !.::, -@:"o r:::.@_. I -@-:%@. :.... ._1-.:-::.:..:.-.::7,-'.1`-.':!:m .,...,... -.... .... ..:,..:.7..::::: ..............I.... '. r:. .. ...I , @ - ..- -.....@.. .. ... ..... ...,-,..... ...*-.-.. -,---!0.*,:--,.:: :11: -- --:r::-::-:-:i1i,: ": .:.,... _...@@ ., :::..::,....!: .:1 ....I.. ... I .@, ::..,.,:* .; :: :..' . . .@.% ...@...: . : X .. .'.A.:@- Xr' : ;.- .: . : ::@ - -*- .--. . .. . -:-".-:-.-: . -@.. ..,.. ..*. I ` 1: ". .I.. ..@:.. .. ..... - .::,.:.. --..%. . ;: : :: '., -, ......-..... ..,'......, ... --....,. ..I-.1. :,.:. ... :: -----. .:@.....X% . . Y:1. :.. : : . .- :. .. : .:.. -'.-;-:,:-X -- ...... .I..... : ...M,::: -- '." - '.:.-;'. - - .- ' - '- ' '.. @**. r -I..... . -- .... .. . ....* !:: i., '::.:::,: @..,::_%.,,:..-,. . . . ..@.:...@. .. . . I . . . I: :@. --. . ... . @....I... . ,:.:,.. :.. .::r... . ..X .......'...... --I:-::...".......,.:..... - -'.-.',..... @ .@... . .:,.: .@ @. . ., :: I., .... I ......".:::... * - . @: X.- .::::,...:.. ,' .:!: : ..-:....!_,. ._- Z . .1. .. .. . . . - - - ... a . I...@ .. .11.. ..1. . .. Several hypotheses have been proposed to explain why marine orga- .:: 1- ::@@.,@...-@,,@i-".-.--..:@:...'*.@.., --:'-.@@.%,':@@--...' ...... ..:::.._.@ .-.@:..-. ;..::.,..::: .........@:: *..!@e:::!-.*@::--,: .it j.@:....:. .: ,.: .:. ::', I @... .. ...1:.@ .,-.:: .:.,.: .. ............@... --_., ..:.. N:.:.:...'..' :, I..::. @:-. _X,.: .... '. . ... ... %...::..'.: C.'.'.,: r I - '-.... 1. I @. __ .I-:....... . r'.. _:-.:-:-...1. ... .... II':::::. -:.-:.% ,::,.:.... ::. @-:: r-:::: ":".:::: ..-. -_-_.,:'.:::,:::.- ..'....... @. :.: ..:.::....:::I.N...:, .1 @... I.. ...... ,:.@- *':-,:; ...@.::,.: . ..... .. . ..... . ..%..:::.:. ........_.......w.,::':. ::r' .1 ':--:-1.-. .. ..",:., @, ., . ..'r. . -r... ** * . , ,"'.I.....'... '. .@: @@::..: - .:.::.. - ....@.@.'..... . '0@. r. ....-I -...W............ " ...... 41.:: ... - r. ...... ::1.-:-.-.-... .1 ....,V.. '.,:..,:. %@ ....... . . . ._ @.:;. ;_r '-- -, ...-....@:.." ...-...-r.._: ...:::::: ....:-. .,.. ........ . . . .e.. ..:.,-.,..: .... .:::: -... @ ..... -% ,.. - - @::. ,:,I....@*. . ." " * * * "I" 1% "*'.:: .;;@ ._... - I............: . .:-.':':" :'r '.', - :--..........'......... _-@, '-. ,* ......! :@ ....@-. --:..I-*- ", 11 1:1 1:1 : 1,.,,,,, .:, ..-:: .. ...:- ..... -....@-":... @ ":... :::.,:. -......-jp-.@::-.,.@ :,:-.*,*: :@- ":..::::::.::..,.,.,. -:-... I .. ;, .... I........-.... ..... . .. - -.. . .@... nisms migrate vertically. The dark provides relative safety from preda- e.-.-;-;:;-,; ::,:..:,::._ A. '..--- .............. .1 X. .--. r. - .... ... I :... _-... ...... --:-,-::-: , ::r.."'.......-: - .:,. w...."',..... ...... .:..:::_:.:. ': ., !:::....::. -.,. ...f......."...:r..-. ... ...--.1 . @.11 - .r.::_ @; ... r-. ... 1. ..... r ....:_w: .--'-:"-. ...:,'. 'I.:::..::.:.,-@'.'* -'.- --.- @.. -.,- .:::.:::.: saa.........:.. . ,-I.1. -_ ...., .:.:: - .::;:::. ...@... ...@.'r.: . .... -..... ,,........... ....... .. ,; :. ..-.-.-:..:.:.: .........,... @ , .-. ...". . ." '.1:1 1':.:.:..,r... _'. .% ....... .... , "....... X:...::,X.::. "' @_ @':'::;'::.' --::.%-1-r--...'- .:%::,:. : : .1 - -:::; .."...::,:.. , :. --l!'... -::: I.."..... .... I .:..%... , 1. .@...."-.,.-,-.....@.,.@...@.,.,.@..., ..: .,.:. :.:,...._%._..,:: - -,:....:....r..;,;. ..'.....'..,._.......... .: ...... X.., .........._ I.. .... ... . ...:: @': ,.-..----.__ I., .. ....... @ ..:.. -1 . 1:..@::.:-.-. .... ** ._., - :. .%1:1--:....:..-'.., _:@ @.....-..., .... ...,,........'...",I...-...". -.-.-...--- ...... ::1.@..:-:-:---..- tors; cooler water in the deeper layers lowers metabolic rates so that less V.............'.... -::@_ ,.:., :.@: . I. --r ... ..r:....... 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N.-...'..-,::::, '....... - : .: -,::,..,:::,:, ': -... a... ::@@@ii@@ii@ii@@ The vertical migrations of zooplankton have been monitored with echo .:1: 0I@ i@i@i@@@i@i@i@i@;@@i@i .: :::::::::i:@:,*.i:::]:]::::;::,:::...I -%`1:: ...:" -..,:.:,.:.:, .":. - .:.:. .,: : 1:1. -:: -., 1% - , - 1: .:.:.::::::::::::" - *:** ** - I :-,..--.-.'..'-.;'-%,: :::--.,%.%, ... .I...... I. ....,......: ............. ......::..; ::. ...,. --- : .,.: ._ ........'.."... :::: .....'::: .. .E......'............... . .__ ..... "', -%:.-.,.`0%1 1:,,,; .. %-%. . . . . ".. ,'. ...... .11 ... 11 ....- .. -... ...... sounders. Certain of these organisms form a sound-reflective layer at ... .. . @ middepth known as the "deep-scattering layer." This layer has been 011@F_@_ VEP_T_1CAL_ M, 14@1@TION detected at less than 200 meters at night and as deep as 800 meters by Figure 45. Diel Vertical Migration day (4). The daily cycle of ascent and descent of marine organisms in represented here by three common species, follow a reverse response to variations in sunlight intensity, such as shown in this pattern; they are lowest in the water when the sun is highest and rise diagram, is referred to as diel vertical migration. Across the top of toward the surface as the sun sinks. Some, like the sergestid the diagram is the approximate position of the sun, beginning on shrimp, do not necessarily come to the surface but merely rise the left with a high at noon, dipping to a low below the horizon at some distance before descending again. - midnight, and rising again to another noon high. Marine organisms,I I 1. , , """", -"-*@*-`* @.....-i-%. .-,---.f----- ...........'... @i ,...,,.-,!@ . ! ....r , ..... , . N `@ , " ol - .. " - - .. , , I - .. . , I - - ,N . ** .1, 11 - - - I .i.i @ , @ ,S nn UU [PUMMUCH . . IMPORTANT ZOOPLANKTON-COPEPODS AND EUPHAUSIIDS Copepods Euphauslids Zooplankton Production ince herbivorous zooplankton depend on phytoplankton for food, their distribution is closely tied to the seasonal and spatial changes in the marine phytoplankton community. Zooplankton populations experience a burst in production during the spring in response to phytoplankton growth, but lag somewhat behind, until sufficient numbers of prey are available to exploit. In the summer, coastal zooplankton abundance is approximately five times that found during the winter (9). Zooplankton are most numerous within a few kilometers of the Oregon shoreline and then decrease rapidly farther west. Typical abundance 1.6 kilometers (1 mile) off Newport during the summer is from 5,000 to 15,000 individuals per cubic meter of sea water. At 16 kilometers (10 miles) west opepods are the most numerous zooplankton group on the uphausiids, large zooplankton closely resembling shrimp, of Newport, the average abundance in the summer decreases to roughly continental shelf. Most zooplankton samples collected off reach a maximum length of 22 to 24 millimeters (about one 1,000 individuals per cubic meter of sea water (12, 14, 15). The highest Newport have contained more than 90 percent copepods. inch). They are larger and more complex and pass through concentrations of continental shelf zooplankton are found in the upper They are also an extremely diverse group; fifty-eight species of more stages of development than copepods. Over a dozen 20 to 30 meters of the water column. copepods have been identified from Oregon's shelf waters (13). species of euphausiids live off the Oregon coast; Euphausia pacifica is Over the continental slope and in oceanic waters, copepod density in The copepod Calanus marshallae is a common species along the the dominant species in offshore waters (19), while Thysanoessa pacif- summer is approximately twice that of winter. Although the highest Oregon coast. Its body is composed of segments, with each segment ica is the most abundant species over the shelf (7). concentration of copepods occurs in the upper 39 meters of water, many bearing a pair of appendages. The appendages surrounding the mouth Euphausia pacifica migrates vertically in the water column to feed (see individuals live below 40 meters in the offshore zone (10, 11). are used to gather and ingest phytoplankton, while those located at Figure 45) and is both herbivorous, grazing extensively on phy- Distinct changes in the species composition of the zooplankton also midbody function much like oars, propelling the animal through the toplankton, and carnivorous, preying on small zooplankton. In turn, these occur seasonally. During the winter, northerly currents bring many water. Although copepods cannot swim effectively against ocean cur- euphausiids are the most important food source for many nektonic species with southern affinities into the Oregon coastal zone. When the rents, many species are capable of daily vertical migrations. species, including herring, Pacific sardine, jack and Pacific mackerel, direction of the predominant surface current reverses in the spring and Development of copepods from eggs to adults is a complex process. A rockfishes, salmon, shrimps, myctophids, and baleen whales. Other summer, many copepods typical of more northern habitats occur off the copepod molts a total of 11 times before becoming an adult. In the case zooplankton, including other euphausiids, also prey on E. pacifica (3,15, coast. of Calanus marshallae, this molting process leads to more than just 19). morphological changes. Accompanying development are habitat The Antarctic species Euphausia superba, also known as "krill," occurs changes within the coastal zone. Adults and the oldest juveniles are in large swarms and is the principal food for baleen (filter-feeding) found west of the summertime upwelling front, eggs occur within the whales. Recently, the Japanese and Russians have shown an interest in upwelling front, and the youngest juveniles live east of the front (14). commercially fishing the abundant stocks of the Antarctic region. REFERENCES Note: References are cited in text by number. References marked with an asterisk (*) are recommended because they are comprehensive, easily understood, and accessible. 1 .Anderson, G. C. 1964. The Seasonal and Geographic Distribution of Primary Productiv- ity off the Washington and Oregon Coasts. Limnology and Oceanography 9:284-302. 2. Anderson, G. C. 1972. Aspects of Marine Phytoplankton Studies Near the Columbia River, with Special Reference to a Subsurface Chlorophyll Maximum. Pages 219-240 in A. T. Pruter and D. L. Alverson, editors. The Columbia River Estuary and Adjacent Waters, Bioenvironmental Studies, University of Washington Press, Seattte, Wash- ington. 3. Grinols, R. B., and C. D. Gill. 1968. Feeding Behavior of Three Oceanic Fishes (Oncorhynchus kisutch, Trachurus symmetricus, and Anaploporna fimbria) from the Northeastern Pacific. Journal of Fisheries Research Board of Canada 25:825-827. 4. *Gross, M. G. 1972. Oceanography: A View of the Earth. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 4. Krygier, E. E., and W. G. Pearcy. 1981. Vertical Distribution and Biology of Pelagic Decapod Ctustaceans off Oregon. Journal of Crustacean Biology, pp 170-95. 5. Pearcy, W. G. 1972. Distribution and Ecology of Ocean Animals off Oregon. Pages 351-377 in A. T. Pruter and D. L. Alverson, editors. The Columbia River Estuary and Adjacent Waters, Bioenvironmental Studies, University of Washington Press, Seattle, Washington. 6. Pearcy, W. G. 1985. Personal communication, College of Oceanography, Oregon State University, Corvallis, Oregon, 7. Pearcy, W. G., and R. M. Laurs. 1966. Vertical Migration and Distribution of Meso- peiagic Fishes off Oregon. Deep-sea Research 13:153-185. 8. Pearcy, W. G., M. J. Hosie, and S. L. Richardson. 1977. Distribution and Duration of Pelagic Life of Larvae of Dover Sole, Microstomus pacificus; Rex Sole, Glyptocephalus zachirus; and Petrale Sole, Eopsetta jordani, in Waters off Oregon. Fishery Bulletin 75:173-183. 9. Peterson, W. K. 1972. Distribution of Pelagic Copepods off the Coasts of Washington and Oregon During 1961 and 1962. Pages 203-218 in A. T. Pruter and D. L. Alverson, editors. The Columbia Estuary and Adjacent Ocean Waters, Bioenvironmental Studies. University oi Washington Press, Seattle, Washington. 10. Peterson, W. K., and G. C. Anderson. 1966. Net Zooplankton Data from the Northeast Pacific Ocean: Columbia River Effluent Area, 1961, 1962. Department of Oceanogra- phy Technical Report 160. University of Washington, Seattle, Washington. 11. Peterson, W. T., and C.B. Miller. 1975. Year-to-Year Variations in the Planktology of the Oregon Upwelling Zone. Fishery Bulletin 73:642-653. 12. Peterson, W. K., and C. B. Miller. 1977. Seasonal Cycle of Zooplankton Abundance and Species Composition Along the Central Oregon Coast. Fishery Bulletin 75:717-724. 13. Peterson, W. K., C. B. Miller, and A. Hutchinson. 1979. Zonation and Maintenance of Copepod Populations in the Oregon Upwelling Zone. Deep-Sea Research 26A:467-494. 14. Peterson, W. K., R. D. Brodeur, and W. G. Pearcy. 1982. Food Habits of Juvenile Salmon in the Oregon Coastal Zone, June 1979. Fishery Bulletin 80:841-851. 15. Proctor, C. M., et al. 1980. An Ecological Characterization of the Pacific Northwest Coastal Region, Five Volumes, U.S. Fish and Wildlife Service, Biological Services Program, FWS/OBS-79/11-79/15. 16. Raymont, J. E. G. 1980. Plankton and Productivity in the Oceans, Vol. 1: Phytoplankton. Pergamon Press, Oxford. 17. Ryther, J. H. 1969. Photosynthesis and Fish Production in the Sea. Science 166:72-76 (see also letters in Science 168:503-505). 18. Smiles, .,and W. G. Pearch. Size Structure and Growth Rate of Euphausiapacifica off the Oregon Coast. Fishery Bulletin 69:79-86. 19. Strickland, R. M. 1983. The Fertile Fjord. Washington Sea Grant, University of Washington, Seattle, Washington. 20. Tyler, H. R., and W. G. Pearcy. 1975. The Feeding Habits oi Three Species of Lanternfishes (Family Myctophidae) off Oregon, USA. Marine Biology 32:7-11. 21. Walsh, J. J. 1981. Shelf-Sea Ecosystems. Pages 159-196 in A. R. Longhurst, editor. Analysis of Marine Ecosystems. Academic Press, London. 22. Willis, J. M., and W. G. Pearcy. 1982. Vertical Distribution and Migration of Fishes of the Lower Mesopelagic Zone off Oregon. Marine Biology 70:87-98. 42 F LA H KIM H CHAPTER FIVE. HEKU(o1N1 The Swimmers ::7::-V TEI T INTRODUCTION t-APWAF s. una, salmon, perch, anchovies, herring, squid, and other familiar marine animals are classified by marine biologists as nekton 14 because of their ability to outswirn the ocean currents. Unlike .......... the passively drifting plankton, nekton swim widely throughout the ocean to feed and reproduce. The nekton inhabiting Oregon's ocean include two major groups of marine animals: invertebrate squids and vertebrates fishes. Sea birds and marine mammals are often classified Wn, as nekton since they too pursue a swimming mode of life (see "Marine Birds and Mammals: Residents and Visitors'' for a discussion of these _J I two animals groups). Figure 47. Northern Anchovy Egg and Larvae Dis- Nekton occupy a variety of niches within the marine ecosystem, both as tribution off Oregon (July 1976) predator and as prey. These niches change as individual fish mature from tiny, free-drifting larvae to mobile juveniles, and finally to predatory The spawning and release of eggs occur west of the Columbia adults. Increased physical size and improved swimming abilities permit River. During summer, the Columbia River plume carries the J-0 planktonic eggs and larvae south and offshore. The mechanism by nekton to capture increasingly large bundles of food and thus gradually @0000%. ) 0 0 which these larvae return to the continental shelf and estuaries '0 0 0 progress from herbivores to first-, second-, and third-order carnivores. OOOOOL 10 0 0 where they are later captured as juveniles is unknown. Reversal of Although less vulnerable as they grow larger and develop mobility, 10 0 (1 00 0 the current and onshore flow in the summer or fall may play a role in 00 0 0 0 maturing nekton nonetheless continue to be prey to larger nekton. 6e_H60,C0,Z- r 10000000 this process. 0 0 (1 00 000k Nekton are important to oceanic food webs and ecosystems as well as to ')0 0 0 0 0 C @0 0 human populations. Throughout history, two major nekton groups, squid 300 sp'A'AlIVINt 0 n n 0 0 0 and fish, have been valued as an important food source. Many cultures A11fZ_r 5AILEY I nor, developed around the opportunity to seek, catch, and process fish. Indeed, Oregon's coastal economy has been anchored in the commer- Figure 46. Migration Route of Pacific Whiting off the cial and recreational fishing industries supporting fishermen and the U.S. West Coast onshore network of processors, marine supply dealers, and boatyards. Adults spend the summer feeding on the mid- and outer continental This chapter of the Oceanbook describes a few general characteristics shelf of Oregon and then migrate south to southern California and of nekton and then provides more detailed information on important Baja to spawn. species found off Oregon. The Oceanbook is not intended as a complete guide to the nekton of the Oregon coast; rather, it is limited to the most tion of nekton. For instance, myctophids can match the ambient light of abundant prey species and the most important commercial species. And the environment through control of ventral light-producing organs, which because the fishing industry is so important to Oregonians, the chapter make the animal difficult to discern against the dimly lit background. includes a brief overview of commercial fishing. Likewise, because all red light is filtered out at these depths, the red pigmentation of the sergestid shrimp and other nekton appears black and thus aids concealment. NEKTON CHARACTERISTICS The depth of the sun's penetration into the ocean influences the vertical Body shapes vary widely but are adaptive to the needs of animals in the ndowed with an ability to swim, nekton roam the ocean, distribution of nekton, most of which ultimately depend on food pro- ocean environment. Tuna, with their streamlined bodies, are rapid especially as part of the cycle of spawning, rearing, and duced in the euphotic zone. Many of the larger nekton are known to live swimmers and can migrate many hundred kilometers. Sole, a kind of feeding. Many species migrate long distances throughout their in deeper water during the daytime and rise to the surface at night, flatfish, lie on the bottom, both eyes on the top side of the head. life history. The Pacific whiting, for instance, spawns off south- following their prey, which are in turn rising to the surface to feed on Rockfish, round-bodied and relatively slow swimmers compared to the ern California in winter and then moves northward over 1,300 kilometers phytoplankton in the ocean's upper layers. This vertical movement in the tuna, are nonetheless quite maneuverable as they graze around their to summer feeding areas off the Oregon and Washington coasts (see water column, often extending over several hundred meters, is known as rocky home. Figure 46). Salmon, steelhead, and sea-run cutthroat trout are ana- diel vertical migration (see "Plankton: The Drifters"). Feeding behavior is extremely varied among the nekton. Some, like dromous fish; that is, they begin their migration in fresh water, spend Many nekton have developed adaptations for concealment based on the sharks, are rapid-swimming midwater predators that pursue and over- most of their lives at sea, and return to fresh water to reproduce. depth of light penetration. Epipelagic species, those living in the upper take their prey. Others pluck their prey off the bottom. Still others, like Albacore tuna migrate across the North Pacific Ocean to feed in summer 200 meters of the ocean, are usually countershaded, silver or gray above the large clumsy sunfish Mola, float at the surface and feed on small off the Oregon continental shelf. In general, larger fish tend to travel and light below. Such cryptic coloration allows the fish to blend with its gelatinous zooplankton. farther than smaller ones (11). environment. Below 200 meters, bioluminescence is a common adapta- The vast majority of nekton produce small eggs which are nearly always IMPORTANT NEKTON SPECIES OFF OREGON laid in midwater and drift with ocean currents (see Figure 47). Although nformation on the distribution, migration, reproduction, and trophic most nekton species produce tremendous numbers of eggs (an excep- relationships of the major nekton species in Oregon is summarized tion is the shark, which produces approximately 12 per year), mortality is below. These species represent the most abundant and important high. Fertilization is external in most nekton and eggs develop externally. prey species within the pelagic ecosystem as well as the most However, notable exceptions exist. Salmon deposit their eggs on well- important species harvested for human consumption. prepared gravel beds in freshwater streams, and Pacific herring affix eggs to the rocks and vegetation in bays and estuaries in gooey mats. In Invertebrates other nekton species, like rockfish and sharks, fertilization is internal. The eggs mature within the female's body cavity and the young are born alive. In general, egg production off Oregon coincides with the season of peak food abundance in the spring and summer. Since the eggs are charac- teristically small, with little yolk, the larvae must feed themselves. The tiny larvae (3 to 10 millimeters) drift in ocean currents from the spawning area to the nursery area, usually in shallow water. Here they feed on zooplankton and grow rapidly until at the end of the larval stage they "A/?1<ET _-5c@UY) LOLL90 OpdLe-scens develop fins, scales, and other features of the adult. The young adult fish then move from the nursery grounds to the feeding grounds, which are often in deeper water. Fishery biologists believe that adult fish may make SQUID Loligo opalescens use of subsurface countercurrents to move from the feeding grounds to the spawning grounds (111). Range. More than a dozen species of squid live off the Oregon coast (30). One of these, the market squid L. opalescens, is common in coastal Oregon's estuaries play an important role in the life histroy of many waters between Baja California and southern Alaska. nekton species. Salmon use estuaries for migration, food, shelter, and physiological acclimatization prior to moving into the ocean. Several Age/Maturity. Squid live one to two years and mature eight to ten flatfish species, especially English sole, use estuaries as nursery months after hatching (49). grounds during their first year of life. Pacific herring lay their eggs in the Reproduction and Early Life History. Following mating, which occurs intertidal zone of Yaquina Bay and continue to use it as a nursery and from April through August, female squid attach several dozen egg feeding ground, clusters to the bottom. Adults die after spawning. Larvae hatch after Harvesting fish stocks is still one of the major uses of the ocean, and three to five weeks. Spawning grounds off Oregon are located in water many of the nekton living off the Oregon coast are important to Oregon's S H R I M P Sergestes similis less than 60 meters deep between Bandon and Cape Arago, off the commercial fishing industry. These fish are harvested as two major Range. S. similis ranges from Japan eastward to the west coast of North Coos Bay North Spit, in the vicinity of Heceta Head, off Newport, and in groups: groundfish (those living on or near the seafloor) and midwater America. the area surrounding Cape Lookout (23). species (those living higher in the water column). Groundfish include Trophic Relationships. Squid eat euphausiids, copepods, shrimp (Ser- flatfishes (halibut, sole, flounder), rockfishes (many species), sablefish, Migration and Vertical Distribution. Off Oregon, the distribution of S. gestes), crustacean larvae, northern anchovy, and other cephalopods Pacific whiting, Pacific cod, and lingcod. Important commercial species similis changes seasonally. The center of maximum abundance moves (34). Predators include coho and chinook salmon, rockfish, sanddabs, living higher in the water include albacore tuna, coho salmon, and from the continental slope in the summer onto the continental shelf lingcod, petrale sole, seabirds (arctic loon, cormorants, sooty shear- chinook salmon. during the winter (69). S. similis, like several other common pelagic water, short-tailed shearwater, northern fulmar, gulls, rhinoceros auklet, Many important commercial fish'species, like salmon and rockfish, are animals, migrates vertically each day. At night, most sergested shrimp common murre), and marine mammals (elephant, fur, and harbor seals; also caught in the recreational fisheries. Other species frequently caught can be found in the upper 100 meters of water. At dawn, the bulk of the California sea lions; porpoises) (51). by recreational fishermen are redtail surfperch, lingcod, surf smelt, kelp population migrates to depths greater than 200 meters where they will Fishery. Although the presence of squid has been known for years, a greenlings, and cabezon (25, 26). remain until dusk (69). strong fishery in California held down the price. The aftermath of the Reproduction and Early Life History. Off Oregon, S. similis lives just 1982-83 El Nino and low production in California made it profitable to fish over one year. Spawning occurs throughout the year, but only a few for squid in Oregon (33). Squid have been recently landed in small individuals reproduce during the summer (69). quantities in Newport. Market squid are harvested when they form Trophic Relationships. Sergestid shrimp feed on copepods, euphau- spawning schools in shallow water. Shrimp nets, bottom trawls, purse siids, chaetognaths, and amphipods (32). Among the predators of these seines, and lampara nets have been used to catch the market squid. shrimp are fish such as albacore and Pacific whiting (55, 3) and baleen Efforts are currently underway to assess the biomass of the Oregon whales (55). squid resource. It is unknown what level of fishing intensity can be Fishery. Although abundant, this species of shrimp is not harvested sustained by the present stock. commercially. 4 0 Vertebrates Fishery. Commercial fishing for albacore by U.S. vessels takes place from the continental shelf to over 1,600 kilometers (1,000 miles) offshore. Most of these fish are harvested by trolling with jigs. The albacore which belong to the northern substock are also fished off Japan. The annual landings of albacore in Oregon are shown in the Table: "Commercial Fish and Shellfish Landings 1970-1983." A 1VAC_1<E_1ZE_Z_ Tr6churus s@tnnvtr@wq JACK MACKEREL Trachurus symmetricus Range. Jack mackerel range from Baja California to Alaska. They were especially abunda AL,5AC0P-_F_ 7-UNA Thunnus aLaLunq& nt off Oregon in 1983 and 1984, possibly as a result of -83 El Nino event (67). the 1982 Migration and Vertical Distribution. Most data about T. symmetricus ALBACORE Thunnus alalunga are from California waters where commercial and recreational fishing is Range. Albacore tuna are distributed throughout the North Pacific common. They live in the uppermost 100 meters of water and frequently Ocean. Two separate groups seem to exist within this range, each form dense schools. Small individuals are most abundant near the coast having different migratory behavior (39). A northern substock, represent- and islands of southern California. Larger fish school offshore over the ing albacore caught off Oregon and Washington, migrates between the continental slope along the west coast of North America. Adults migrate eastern and western North Pacific. A southern substock, encompassing D0V5_1Q_ _50Z_E Microstornus pac@FLWS northward and westward from their wintering range off Washington, fish caught off southern California, does not make trans-Pacific migra- Oregon, and California (49). As surface temperatures decrease, fish may tions. During the summer fishing season, no exchange of fish is known to descend into warmer, deeper waters. occur between the California and Pacific Northwest substocks (38). DOVER SOLE Microstomus pacificus Age/Length/Maturity. Jack mackerel are long-lived and may reach 30 Migration and Vertical Distribution. The seasonal migration of albacore Range. Dover sole range in distribution from Baja California to Alaska. years and a maximum length of 76 centimeters (approximately 30 into the waters of the Pacific Northwest is thought to begin in late May Areas of major abundance in Oregon are off Coos Bay and the Columbia inches). They mature between two and three years of age (49). and June when fish move from the central North Pacific into waters River. Dover sole prefer mud and muddy-sand bottoms on the outer shelf Reproduction and Early Life History. Mackerel spawn in areas from located 1,000 to 1,600 kilometers (625 to 1,000 miles) off the coast (39, and slope (19, 66). Figure 48 shows locations where Dover sole are 150 to 450 kilometers (approximately 281 miles) offshore (45). The center 92). They then migrate eastward as surface waters begin to warm. caught. of peak spawning moves northward during spring, summer, and fall. Albacore first appear off northern California and southern Oregon in Migration and Vertical Distribution. Younger fish live in shallower water Mackerel off Baja California spawn in March and April, whereas off midsummer. While off the coast, these fish tend to aggregate in the than adults. Seasonal changes in depth distributions also occur. Oregon peak spawning occurs during the fall (36). It is not known if the vicinity of upwelling fronts or at the edge of Columbia River plume water Females migrate into shallower water during the summer, whereas seasonal shift of spawning results from later maturation of the more (38, 64). By late fall, albacore have left Oregon and moved into oceanic males remain in deeper areas all year (2). northern individuals or if spawning adults migrate north as surface waters. Physical factors such as water temperature and the structure of waters warm (61). Jack mackerel eggs and larvae have been found 160 oceanic fronts can affect the timing of this migration as well as the Reproduction and Early Life History. Spawning occurs during the to 1,600 kilometers (100 to 1,000 miles) off the Oregon and Washington distribution of albacore (39, 63, 31, 9), winter in areas deeper than 400 meters (74). Larvae live in the uppermost coasts in August (1). Maturing fish move onshore for the first three to six Rather than spending most of their time in surface waters, as was 50 meters of water for at least one year. They are distributed over and years and then move to deeper water and further offshore (49). previously thought, albacore are frequently found within and below the beyond the continental slope. Off the Columbia River, Dover sole thermocline (38). Fish swim over a range of depths, with the range being eventually settle to the bottom near the edge of the continental shelf Trophic Relationships. Jack mackerel off southern California feed on larger during the day than at night. Albacore may encounter up to 70 C (12). copepods, pteropods, and euphausiids (8). There are also reports of change in water temperature over a 20-minute period when moving Trophic Relationships. Pelagic larvae eat zooplankton. Adult Dover sole juvenile squid, northern anchovies, and myctophid fish being eaten (14). vertically (38). feed on benthic invertebrates such as polychaete worms, ophiuroids Jack mackerel are generally not an important food source for other Reproduction and Early Life History. The spawning grounds for the (brittle stars), crustaceans (amphipods), and molluscs (14, 71). marine life (61). northern substock of albacore are located in the central North Pacific Fishery. The Dover sole has been the most important flatfish landed in Fishery. If an expanded, open-ocean purse-seine fishery develops off between Hawaii and the Philippines. Spawning occurs throughout the Oregon since the trawl fishery began in 1973 (12). Despite yearly Oregon, jack mackerel may become a significant commercial species year, with a peak in summer. Albacore found off Oregon are sexually fluctuations in landings, Dover sole has consistently remained the (44). immature three- and four-year-old fish (92). dominant flatfish. It is also one of the few groundfishes present in Trophic Relationships. Albacore feed on juvenile stages of anchovies, sufficiently high concentrations beyond the continental shelf to support rockfishes, jack mackerel, and Pacific saury as well as squid, euphau- a deepwater commercial fishery. siids, and amphipods (10). MX-nT_0P111DS A 5 'A 7 _11z 5 q1 Y AV,!'--l /0 V Y Enqr<@@uUs morday, Clupea Tiarengus -paita,@;L MYCTOPHIDS NORTHERN ANCHOVY Engraufts mordax PACIFIC HERRING Clupea harengus pallasi As a group, the myctophid fishes are the most abundant of all midwater Range. Northern anchovies live along the west coast of North America Range. Pacific herring are widespread throughout continental shelf fishes. One of them, Stenobrachius leucopsa(us (northern lampfish), is between Baja California and British Columbia, Three distinct subpopula- waters of the North Pacific. Although distribution near North America the single most abundant species off the Oregon coast (75). Moreover, tions of anchovies are found within this range. Individuals off of Oregon extends from Baja California to the Beaufort Sea, herring are more myetophids are the dominant fish larvae between 21 and I 11 kilometers belong to the northernmost group. The central subpopulation is cen- abundant off Washington and British Columbia than Oregon. (62 to 185 miles) offshore (86). A distinguishing feature of myctophids is tered off southern California and is harvested for fish meal. the presence of many photophores, small, light-producing organs Age/Length/Maturity. The maximum age reached by Pacific herring in located on the body's surface. Age/Maturity. Adult northern anchovies in the northeast Pacific mature the northeast Pacific is eight years, and the maximum length is 23 Length. Myctophids are small fish, usually 10 centimeters (4 inches) or at two years of age and reach a maximum age of seven years (49). centimeters (approximately 9 inches). Pacific herring mature between less in length. Migration and Vertical Distribution. During winter, adult and juvenile two and four years of age (49). anchovies live in nearshore areas. Some of the juveniles move into bays Migration and Vertical Distribution. Adults migrate seasonally from the Migration and Vertical Distribution. Myctophids are mesopelagic; that and estuaries (Tillamook, Yaquina, and Coos bays) when spring arrives. continental shelf into shallow water. is, they live below 200 meters depth during the day. Some myctophid From June through August, juveniles remain in nearshore and estuarine species migrate to the sea surface at night. During the summer, the habitats while adults migrate into Columbia River plume water to spawn. Reproduction and Early Life History. Spawning occurs during late largest concentrations of myctophids are found over the continental Mature adults are typically found from 65 to 157 kilometers (40 to 100 winter and spring (49). Pacific herring lay their eggs in the intertidal areas slope. When the southerly winds of winter produce an onshore flow of miles) off the northern Oregon coast at this time. By fall, adults have of Yaquina Bay. The sticky eggs are frequently found attached to kelp, near-surface water, these small fish become most numerous on the outer returned to the nearshore habitat where they are joined by juveniles rocks, and pilings, After the eggs hatch in about ten days, the larvae continental shelf (65). which have left the bays (37). subsist on the food reserves of their yolk sac for another two weeks before they begin feeding. At the end of their first summer, young fish Trophic Relationships. Myctophids eat copepods, euphausiids, and Reproduction and Early Life History. Fertilization of eggs occurs in move into deeper water on the continental shelf (20). amphipods. Important predators on myetophids are albacore, rockfish, near-surface waters. The eggs are pelagic. Following spawning, eggs Trophic Relationships. Pacific herring feed on zooplankton such as and sablefish (94, 75). and larvae are carried even farther offshore (see Figure 47). copepods, amphipods, and euphausiids, although food habits may Trophic Relationships. Northern anchovies feed on phytoplankton and change seasonally, Herring consume large quantities of food during the zooplankton (for example, copepods, pteropods, and dinotlagellates) spring and summer. Many predators, including sharks, salmon, lingcod, (42, 4). Northern anchovy are eaten by other fishes (Pacific whiting, seabirds, and marine mammals (sea lions and whales) rely on Pacific salmon, rockfishes, jack mackerel, and albacore), many marine birds, herring for food. squid, and many marine mammals (seals, sea lions, dolphins, porpoises, and small whales) (94). With the exception of occasional harvesting for use as bait, the 100,000 to I million metric tons of anchovies off the Oregon and Washington coast remain unexploited (81, 84). no (D 481A cj 12 T C." F.k VVI k Z. fty 4L 0 J-) J- Tk@ Y",I ':, A1-- I-Is -je CO Lu A ul sk- "g@ z;j) Cr jxl: I ir 0 0 ) AZi 0 1" IN !V. c-. 26' 125 1 3. 126' 1125)' 1! 4- L)OVA!!:R A7-Oz@iKi"l-5H (-@OM1W2ffP-,6--1AZ- CW-C-H AF-EA5 Da t6 f ro,-n 0 DCY W, /V7, /;-7 5&=V@O 110Z ecln, 19 76 L6 ta icrorn 00,1:-4 W, 1?77, in 5tander 01106&n, 1'776 Figures 48, 49, and 50. Fishing Grounds for Selected A comparison among the maps will reveal areas where spec Groundfish Species. catch overlap. In Figure 48, Dover sole data are based on This series of three maps shows areas of the continental shelf where records for 1973 and 1975. Figure 49 displays data on rockfi three species of groundfish were caught by commercial fishermen. including Pacific ocean perch, and is based on log records COMMERCIAL FISH AND SHELLFISH LANDINGS (POUNDS ROUND) IN OREGON 1970-1983 1970 __@971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 FISH: I Anchovy, northern ........... I 1 39002 1500 200 300 700 0 0 200 0 Bass, Striped @ .....,.,,, 50051 670B4 54449 39517 35151 18019 2 Bonito, Pacific ..... 0 0 0 0 0 0 0 0 0 0 0 0 0 1462 C.1bezon ,, . ......... 0 0 0 0 0 0 0 0 0 0 0 299 142 702 Cod, Pact c .... ...... 76397 483147 1075675 466186 700607 588029 628939 846913 931676 931704 356522 116947 260319 196644 Flounder, arrowtooth ......... 8653 20781 50903@ 731591 3406W 1018123 7128W 1947083 380564 745000 438774 1311268 1617209 1191733 Flounder, starry ......,,. 585038 613714 521900 463583 613504 887568 1754995 746795 1211186 645989 426768 889441 481812 432560 Grenadier ... ..... ..... 0 0 0 0 0 0 0 0 0 0 0 0 0 798 Hake, Pac. (Whiting) ......... Q 59,35 0 KW3 3641B b320 471987 974687 858049 304700 605298 360251 3316 142536 Halibut, Pacific ... . .... 95170 71601 68571 51601 67630 57878 58149 78500 62998 43448 176684 150396 234730 579560 Herring, Pacific ............. 479334 437281 387264 492181 656291 70867 83613 54874 137231 175448 140723 148410 144970 145915 Lamprey, Pacific ........... 3771 3000 1273 0 4000 3138 865 1481 9090 8935 3233 4666 39169 4482 Lingcod ... ............... 1121325 1534302 1663760 2312925 2167563 1664442 1116570 996228 1180735 1805165 1662778 2307361 3213736 3830684 Mackerel ........... 0 0 0 276 473 5080 2987 3613 810 5231 20 26 83 18253 Opah . @ , , @ , , , . ..... . 0 0 0 0 0 0 0 0 0 0 0 0 0 448 Pollock, walleye . @ ... . .... 0 0 0 0 0 0 0 0 0 0 0 0 0 348 Prickleback, monkeyface ...... 0 0 0 0 0 0 0 0 0 0 0 0 0 302 Pac. Ocean PercW .......... 1612600 1738991 588244 570145 887044 921419 2332603 1446010 1934061 4193424 3615284 4350997 5508130 5192175 Rocklish, widow ....,, 0 0 0 0 1 1 1 31768970 19198987 Rockfish (misc. spip.) ... .... 4238572 4198673 5283943 488304 4022363 3256941 5714320 6457698 11559767 19194651 35173303 18321418 22031780 3029142@ Sablefish ... ... . ....... 161845 274570 449010 1298698 601181 728981 1080658 921098 3816029 17024760 6025840 5166329 11220816 10234762 Salmon, chinook ............. 6311491 5013543 5085474 9595654 4911284 5534955 4820004 6953526 4543434 4BO4950 3954327 2439675 4365148 1287328 Salmon, chum ..... ... 4883 3050 9960 11788 3272 4625 10111 810 13086 338 1824 11118 13964 1100 Salmon, coho . , ........... 13084479 11774660 6482926 7305423 10054741 5823540 11413708 3291276 4148041 6160328 3255659 4156442 4204763 1300319 Salmon, pink . @ .............. 1004 10412 132 16363 81 1041 6378 455566 281 122324 1805 372605 0 269 Salmon, sockeye ,., ,..... 40675 163440 153722 10944 21 7 399 210 50 10 0 0 472 2998 Sanddab, Pacific ......_ 63049 60184 114467 193872 245392 365095 326960 243560 227027 453383 356592 293589 526000 531290 Shad, American . ........... 698248 473822 640844 450747 264505 456758 412635 369780 671598 703166 291414 117477 435351 359719 Shark, souptin ............. 0 0 3755 343 1010 855 2982 1805 856 3049 1791 3585 11081 13905 Shark, spiny dogfish ... 17280 4115 514 906 12701 19367 13330 56090 160326 85446 56305 10608 2090 2581 Shark, other ................ 0 0 0 0 0 0 0 0 0 0 0 1293 8213 7100 Skates and Rays ..... 1137 707 1037 7477 13989 16180 254044 255298 401579 480573 183673 85861 63889 159640 Smelt ... _ ... 148105 134246 133403 62244 424627 9147 19761 956275 7100 791228 328762 24013 55346 40343 Sole, butter ................. 0 0 0 2842 3411 22962 14586 48558 63498 44244 26713 22463 19178 12075 Sole, curlfin (turbot) .......... 7 1 1 1 1 7 10087 2532 1016 5105 9793 9469 Sole, Dover ............. 5606116 5718550 6014291 4572561 5714525 4886918 5018116 4075203 7546417 11226910 9080509 11672995 17951407 18698513 Sole, English ....... 1687586 1804012 2195609 2378570 1786406 2173321 3602636 2171203 2283864 2390661 1584178 1600095 2187335 2014645 Sole. flathead ..... ........ 0 0 0 0 0 33351 59968 22814 18127 31165 7035 11111 6524 17105 Sole, petrale ........ ...... 2151452 2290871 2206880 2244005 2746087 2654859 1764112 1818942 2246190 2330293 1890934 1948665 3323843 2435788 Sole, rex ......... ... 1076279 862727 1324442 1268203 1311021 1010607 1078871 952756 1431578 1638048 1175957 1346409 1865611 1426686 Sole, rock ......... 4488 32495 2425 388 3549 26212 14230 20360 20164 20301 28729 19871 66543 9278 Sole, sand .... ........... 578476 465245 444261 401791 313835 470267 847841 466900 569098 769564 564653 73545B 856930 696583 Sole, slender .... ........... 0 0 0 0 0 0 0 0 64 0 25 0 0 0 Sole, miscellaneous ...., 3337 198 0 2030 2 13017 70492 16595 19252 39777 0 0 0 0 Steelhead . .... ......... 186370 313129 457276 461329 129414 26529 33548 73000 74900 41193 29772 61060 53564 80487 Sturgeon, green ,........ 40017 39920 33823 22247 85771 32974 40945 16721 34995 22243 23240 9990 21219 18970 Sturgeon, white ... ......... 172631 201708 202665 268582 271203 301284 483895 240962 181219 312161 183927 280123 236691 296648 Sunfish, ocean ......... 0 0 0 0 0 0 0 0 0 0 0 0 0 244 Suriperch . ................. 4838 5994 0 1572 B769 D 39 0 2B8 2487 '121 167 342 2421 Tomcod, Pacific ......... 0 0 0 0 0 0 0 0 0 0 0 0 0 46 Tuna, albacore . ............ 21797708 8419585 23056004 16338827 25224720 17165537 5933617 4420159 11285419 3106607 3504715 7726890 1913063 3410429 Tuna, other ............. 5139167 4672582 6177711 8086658 7815206 6418872 11415793 5478762 7112254 5713979 1006 0 580 '177 Walleye ......... 0 0 0 0 0 0 0 0 0 396 0 0 0 0 Wolf-eel . .... ............ 4137 0 0 0 0 505 285 145 688 253 690 1435 2348 6747 Miscellaneous . ..... . 2051413 1825248 750068 612377 742556 994620 631019 552768 122328 97253 227422 335370 1219 53 CRUSTACEANS: Crab, box . ........... 0 0 0 0 0 0 0 0 0 0 0 0 502 16207 Crab, Dungeness ... ., 14929347 14875849 6762259 2349645 3917625 4026937 8134065 19902419 12501274 15631877 18650635 6984025 7035245 5350560 Cralb,rock .................. 0 0 0 0 0 0 0 0 863 2333 178B 7 0 0 Crab, Tanner ..._...... 0 0 0 0 0 0 0 0 0 0 0 0 65 1338 Crayfish .... ..... ....... 39019 39537 8730 9942 12094 26559 11916 32494 11286 20663 78359 83904 155231 125519 Shrimp, brine . @ @ @ ......_, 0 0 0 0 D 0 0 0 0 278 3125 3935 7100 12402 Shrimp, ghost (sand) .......... 6349 8002 10082 12753 14628 19533 27303 33097 57325 46546 57888 55499 68749 69905 Shrimp, pink ................ 13572174 9075006 20731151 24517194 20313760 24083568 25456007 48580070 56666109 29586586 30152030 25923589 18461988 6547073 MOLLUSKS: Clams, bay ................ 40690 58753 74130 34452 24956 27780 88029 75758 215031 9412 80467 74707 131989 136185 Clams, razor . @ , @ ........... 40465 118016 45781 41455 36228 20291 22516 26528 100 Mussels, ocean ............. 0 0 588 0 0 728 666 312 818 19068 60629 17866 18372 28267 Mussels, freshwater . @ @ @ ..... 0 0 0 0 0 0 0 0 0 0 0 0 0 2485 Octopus ...... .. _. ..... 3048 2796 2886 11095 0 7244 14538 4049 16122 24187 14013 14082 18597 16780 Scallop, weathervane ........ 0 0 0 0 0 0 0 0 0 3434 0 16853845 1487941 2648965 Squid ...... ...... ....... 0 0 0 0 0 0 0 0 0 0 a 225 113138 297410 Oysters . ............. 306810 278904 175720 198072 233528 213136 16612 233736 241168 222048 234784 269840 296464 247136 TOTAL .......... 97965370 77666113 93053689 91736521 95838310 86258871 95626041 114590565 135027755 132089781 124742030 148494292 129979815 100608098 INCLUDED IN PACIFIC HERRING. INCLUDES CURLFIN SOLE (TURBOT). INCLUDES ROCKFISH SIMILAR IN APPEARANCE TO PACIFIC OCEAN PERCH. INCLUDED IN ARROWTOOTH FLOUNDER. - INCLUDED IN BAY CLAMS 2 NO COMMERCIAL SEASON. 4 INCLUDES NORTHERN ANCHOVY INCLUDED IN ROCKFISH (MISC. SPP.). INCLUDES MINK FOOD, CARP, WALLEYE AND INCIDENTAL SPECIES Trophic Relationships. They feed on copepods, amphipods, euphau- Trophic Relationships. Pacific whiting eat a variety of food items. siids, fish eggs and larvae (for example, northern anchovy), and crusta- Euphausiids, shrimp, Pacific herring, northern achovy, eulachon, flatfish, cean larvae (29, 27). Saury are an important food for many commercially rockfish, and smelt have been reported from the stomachs of whiting. important fish. Off Oregon, saury is one of the main preyof albacore (64). Seasonal and year-to-year changes in the diet are known to occur (16, Salmon and sablefish also rely on this abundant fish as a food source 41). Predators on whiting include fish (sharks, rays, albacore, rockfish, (17). In addition, marine mammals such as sei whales and northern fur sablefish, lingcod, and arrowtooth flounder) and marine mammals (Cal seals are known to feed on saury (29). ifornia sea lion, northern elephant seal, Steller's sea lion, northern fur Fishery. Japan, South Korea, and the Soviet Union have developed seal, killer whale, sperm whale, dolphin, and porpoise) (5). large fisheries for this species in the eastern Pacific, but the saury off the Fishery. The most productive fishing grounds for Pacific whiting off U.S. west coast are not exploited. In 1968, saury biomass in the eastern Oregon are the area@ around Heceta Bank, Yaquina Head, and Cape 5comber _J .aponict4s North Pacific was estimated at 450,000 tons (29). Blanco. Most fish are caught at between 100 and 200 meters (5). Recent political sanctions against Poland and Russia have essentially stopped the direct harvest of whiting by foreigners. Joint-venture operations have continued, though, with U.S. vessels catching and selling 72,000 metric PACIFIC MACKEREL (CHUB) Scomber japonicus tons of Pacific whiting to foreign interests during 1983 (59). However, Range. Pacific mackerel, a highly migratory species, range throughout foreign interest in the Pacific whiting fishery may be changing since the North Pacific. recent claims have been made that the fish are too heavily parasitized for Trophic Relationships. Pacific mackerel feed on crustaceans, squid, consumption (33). and small fish. Fishery. A commercial fishery exists for this species in California. Although not of commercial importance in Oregon, Pacific mackerel were the most abundant fish caught by Oregon State University researchers in purse seines off the Oregon coast in the summers of 1983 and 1984. As with jack mackerel, the recent intrusion of warm water from California associated with the 1982-83 El Nino event may account for this abundance. merLLACCius py-odur-tus PACIrIC WMIT-IN67- PACIFIC WHITING (HAKE) Merluccius productus Range. Pacific whiting are very abundant between Baja California and British Columbia. Migration and Vertical Distribution. Pacific whiting migrate annually /r@,'A77A/Z_5 from spawning grounds off southern California to feeding grounds off northern California, Oregon, and Washington (see Figure 46). During RATTAILS, Family Macrouridae winter, adults form spawning schools in midwater over the continental Abundance. Off Oregon, rattaiis are the most numerous benthic fish in shelf of southern California. Following spawning, fish migrate northward, water deeper than 1,000 meters (76). first appearing off Oregon in April. By mid-June, large numbers have moved inshore to depths of less than 100 meters. During the remainder Reproduction and Early Life History. Little is known about the biology of the summer, whiting gradually move back into deeper water, and by of this family (91). Larvae and juvenile are rare, only occasionally being fall, move southward again (5). captured in midwater trawls (901 Adult whiting off Oregon also vertically migrate within the water column. Trophic Relationship. Members of this family Macrouridae off Oregon At night, fish are at the surface feeding on euphausiids (3). During the are known to feed on epifauna and pelagic organisms (70). day, whiting migrate downward and form large schools near the bottom. Fishery. 'Two species in this family are an incidental commercial catch PAC_I)c@IC 5AUQY CoLoLabLS _qaii-a Schools can vary in size from 0.5 to 20 kilometers (approximately 0.3 to off northern California. They are marketed in the Eureka, California, area 12.5 miles) long and 0.25 to 3 kilometers (approximately 0.16 to 1.9 miles) under the name "grenadier." wide. PACIFIC SAURY Cololabis saira Age/Length/Maturity. Pacific whiting reach a maximum age of 13 years Range. Pacific saury is a common epipelagic fish off of Oregon. and a length of 79 centimeters (approximately 32 inches). Maturity is Vertical Distribution. Saury are known to congregate around oceanic reached at 4 years (46). fronts such as upwelling regions, which are distinguished by marked Reproduction and Early Life History. The eggs are pelagic and are thermal gradients (29). During daylight hours, saury are found feeding at found considerably offshore. The larvae and juvenile fish are pelagic for depths of 30 to 70 meters. At night, saury migrate to the surface and one to two years in shallow areas of the continental shelf and then join stop eating. Large schools sometimes form at this time. the adult population in deeper water (49). CANARY ROCKFISH Sebastes pinniger ROCKFISH Sebastes spp. The term "rockfish" or "red snapper," is applied to any one of the many species in the genus Sebastes. Over 60 species of Sebastes occur off the U.S. West coast. Range. Figure 49 shows where rockfish are caught off Oregon. Migration and Vertical Distribution. Rockfish larvae are abundant in surface waters beyond the continental shelf (84,86). As juveniles, they more in shore, settle to the bottom, and spread over the continental shelf, where they are addociated with rocky bottoms as adults (7). Reproduction and Early Life History. Reproduction in many rockfishes of the genus Sebastes differs from the of other groundfish. Fertilization is internal and precedes release of larvae by one to four months. Young are born live rather than released as eggs into the water. Commercial catch rates may be high during the mating and spawning periods (60). Trophic Relationships. Young rockfish feed on planktonic crustaceans. Adults are known to consume euphausiids, squid, copepods, amphipods, and fish (7). Important predators on juvenile rockfish include other fish (for example, halibut and albacore), marine birds, and marine mammals. PACIFIC OCEAN PERCH Sebastes alutus WIDOW ROCKFISH Sebastes entomelas Fishery. Prior to 1960, flatfishes were the most important group of groundfish landed in Oregon. Since 1960, rockfish have increased in importance. Among the most important commercial species in Oregon are the Pacific ocean perch, Sebastes alutus, widow rockfish, Sebastes entomelas, yellowtail rockfish, Sebastes flavidus, and canary rockfish, Sebastes pinniger. These species are caught in the deepwater trawl fishery on the continental slope. The widow rockfish, unlike most other species, is mainly pelagic and spends considerable time off the bottom. A midwater trawl fishery has been able to exploit the dense schooling behavior of this species, but landing of widow rockfish have been declining since 1981 (see Table: Commercial Fish and Shellfish Landings in Oregon 1970-1983). Catches of Pacific ocean perch increased steadily throughout the 1960s until Japanese and Russian trawls caught large numbers in 1966-1967. Oregon and Washington landings decreased from 7,200 to 675 tons over this same period. Foreign fishing fleets are now prohibited from fishing Pacific ocean perch. YELLOWTAIL ROCKFISH Sebastes flavidus SABLEFISH Amoplopoma fimbria SABLEFISH (BLACK COD) Anoplopoma fimbria Range. SAblefish range along the outer continental shelf and upper slope from Baja California to the Bering Sea and Japan. Figure 50 shows locations where sablefish are commercially caught. Migration and Vertical Distribution. Most sablefish do not migrate great distances along the coast (24), but a seasonal shift from shallow water during the summer into deeper water during the winter has been noted (6, 79, 35). They are commonly found between depths of 160 and 2,000 meters, with the larger fish found deeper. Age/Length/Maturity. Sablefish are long-lived, with a life span that can reach 26 years. Maximum size reached is slightly greater that 90 centimeters (36 inches). Maturity is reached between 5 and 7 years (49). Reproduction and Early Life History. Mature sablefish spawn along the continental slope throughout their range between September and February. Locations of spawning grounds are unknown. Egg development occurs at the surface. Sablefish larvae are fund at the surface dduring the spring as far as 290 kilometers offshore (180 miles) (6). Juveniles are also epipelagic and form schools near the surface, sometimes far offshore. By fall, juveniles have moved from offshore areas onto the continental shelf (35). Subadults eventually move to deeper water (49). Tropic Relationships. Food items depend on life stage, geographic location, season, and time of day (49). Larval sablefish feed on zooplankton. Adults consume fish such as saury and myctophids as well as euphausiids (17, 35). Sablefish are eaten by northern sea lions, Pacific cod, and lingcod (49). Fishery. Sablefish is a major deepwater, longline fishery. 52 NEKTON SALMON Migration. There are two types of ocean migrations. Spring chinook from Migration. Recent studies have shown that for the first few months after ive species of salmon live in the waters off Oregon: coho (silver), the Umpqua River and spring and fall chinook from areas south of the Elk reaching ocean water, juvenile coho may be distributed south of their River remain off the southern Oregon and northern California coasts entry river. By late summer, most have moved north of the point at which chinook (king), pink (humpy), chum (dog), and sockeye (red). throughout their life (59). The western limit of their distribution is not they entered the ocean. Some juveniles may remain in coastal waters in Two of these, coho and chinook, are important to Oregon's clearly defined but may extend several hundred kilometers offshore. the vicinity of their release point (67). commercial and recreational fisheries. Chum salmon, though Chinook originating from coastal streams from the Elk River north, as well numerous in Oregon at one time, are less abundant today. Sockeye and as from the Columbia River, tend to move northward. Most of these fish Some Oregon coho have been known to move as far north as the Gulf of pink are not caught in large numbers off Oregon, but are abundant in migrate as far as northern British Columbia before returning to their river Alaska by the end of their first summer at sea (15, 21). The proportion of areas farther north. the Oregon coho stock that makes this extended journey is unknown. of origin (21, 46). However, scientists believe that only a small number of fish, from various Trophic Relationships. Chinook off the Oregon coast eat euphausiids, stocks, are involved and that the migration is tied to oceanic conditions amphipods, crab larvae, squid larvae, and fishes (79, 80, 22). The diet of encountered by coho smolts where they enter the ocean. Likewise, the harbor seals includes adult salmon. route taken by these fish on their return migration is not well docu- mented. Most coho stocks produced in Oregon (hatchery and wild) remain in ocean waters off California, Oregon, and Washington (56). Trophic Relationships. Juvenile coho salmon eat primarily euphausiids, amphipods, crab larvae, and fish (77). Among the fish eaten, the Pacific sand lance, juvenile rockfishes, and juvenile flatfishes are most fre- der coho are nown to ee on eup aus quently consumed. 11 S, 0 il. a@ --,1 1. squids, and other fishes (15, 80). Among the predators of young salmon are rockfish and other large fish, including salmon, and the common murre, a seabird which is known to eat juveniles as they migrate into the ocean, Adult coho are consumed by harbor seals, sea lions, killer whales, and sharks. OncorhyncAAs tshawyt-sr-ria 11A7URF- AP4Ar!@ FALL CHINOOK SALMON Oncorhynchus tshawytscha 9@57VJ" 7V @,7RE@a*4 5 Apal@ 0ncc)rhjncjjs K5Litjr_h CE-AR@L7_ AM@ 1,PAWH (74 Fke5HW,@,7E@@ 'M" - '_ ANO DA@- Range. The distribution of North American chinook salmon is somewhat M. 11&= @11A I) I broader than for coho salmon, with individual stocks ranging from summg:p. '@@-WINTgA southern California to the Gulf of Alaska, the Aleutians Islands, and the COHO (SILVER) SALMON Oncorhynchus kisutch A,:;Ul _r', rAkt-7V 1"i e@A-rF IN 61@F@ MO/I Bering Sea. They are also found off the coast of Asia. Range. The coho stocks of North America range throughout the eastern Reproduction and Early Life History. Many chinook stocks reproduce North Pacific from central California to Alaska. They are most abundant 51DRINQ 5PRINCT 7VF1q@F_511WA7EQ in the upper sections of large rivers such as the Columbia, Sacramento within this area off British Columbia, the central portion of their range. In AIYO (California), and Fraser (British Columbia), as well as in streams near the Oregon, juveniles spending their first summer in the sea have been coast. Chinook also demonstrate far more variability in the time they found within 37 kilometers (23 miles) of the shoreline (67). Older salmon YEAR- CIVE enter fresh water on their spawning migrations. Rather than having just can occur farther offshore, especially during the winter. Coho also live in one spawning run in the fall, chinook return to spawning rivers through- the northwestern Pacific from Japan to the Bering Sea. out the year. Spring, summer, and fall runs are found in the Columbia Reproduction and Early Life History. The life cycle of coho salmon is 6UNMER River. Oregon coastal streams may have both spring and fall runs or just summarized in Figure 51. Spawning occurs in smaller tributaries of W/ a fall run. @V - @e freshwater streams from November through February. Eggs are depos- IMN CZ 7-611AZI 7@ A'o COHO _@ALMOIY Variability in the chinook life history continues after spawning. After ited in coarse sediments and hatch in a little over one month. (The hatching, chinook may migrate downstream to the estuarine environ- development of salmon from egg to adult occurs in stages; the YEAR- 7WO ment, remain in fresh water for several months before moving into sequence is egg, fry, fingerling, smolt, adult.) Coho fingerlings remain in FAL-L 7WO estuaries, or remain in fresh water for one year and then migrate to the streams for about one year before migrating into estuaries. They then coastal environment during their second spring (40). Typical of this undergo dramatic physiological and morphological changes, called variability are the fall chinook in the Sixes River, a small coastal stream in smoltification, in preparation for entering the ocean. Fingerlings are Curry County, which have five distinct life history patterns based on transformed into smolts when this process is finished. Most coho smolts 5UMMEP WIN7F-P, length of time spent in fresh water and estuaries (82). are 10 to 13 centimeters long by the time they finally reach the sea. C:7DW/Y_4V_/Z9;n1^1 -ro In the Columbia River, the offspring of fall-run chinook remain in fresh After entering the ocean, coho grow rapidly. At the end of their first .5PRiricT water for about three months, whereas the young of spring-run fish summer in the sea, they are 28 to 51 centimeters (approximately 11 to 20 spend one year in the river; however, there are exceptions to this pattern inches) long. Some precocious males (called jacks) reach sexual matu- Figure 51. Coho Salmon Life History. (83). Chinook return to fresh water after reaching an age of from two to rity at this time, return to the stream of their birth and spawn with mature six years. Most are three or five years old. three-year-old fish. The females and nonprecocious males remain at sea The life cycle of the coho salmon is similar to that of all types of for one more summer. Commercial troll and recreational fishermen salmon: birth in freshwater streams, a journey to the sea, a matura- harvest these three-year-old adults, but adult coho not caught return tion phase at sea, and a return to the stream of birth to spawn and during the fall to their natal stream. begin the cycle anew for the next generation of salmon. H IE KTO N go Salmon Fishery. Salmon are harvested in the ocean by trolling with SALMON MANAGEMENT baited hooks on lines. Fishing occurs over the entire Oregon continental uring their life cycle, salmon pass through very different shelf, although activity is usually concentrated in areas less than 150 meters deep. Coho salmon are normally caught in shallower depths than biological environments and many political jurisdictions. Fish are chinook. move from smaller freshwater streams along the Pacific North- Salmon catches off Oregon have fluctuated greatly over time. Following west coast or from the Columbia River system of Montana, Idaho, and British Columbia, through estuaries, and into the ocean to peak production during the early part of this century, salmon catches migrate as far away as the Gulf of Alaska before returning to their native 60 N declined steadily until the early 1960s. This decline has been attributed streams. While completing this extensive migration, salmon are regu- to the construction of dams; the alteration of freshwater habitat by lated by state, regional, federal, foreign, and international organizations. logging, pollution, gravel removal, siltation, dredging, and filling; and overfishing (52, 57). Many of the problems facing salmonid management are related to the vast area traversed by migrating fish, the effect of changing environmen- %A TOTAL 5HOLT15 tal conditions, and the socioeconomic and political demands of all the jurisdictions through which the salmon pass. In addition, the increased use of hatchery-reared salmon in recent years to supplement depressed t wild stocks presents new challenges in managing for "mixed stocks" (hatchery and wild) in ocean and inland commercial and recreational fisheries while attempting to rebuild wild stocks (33). 40 pki-vk-rE Oregon hatchery operations were expanded in the 1960s to counteract tIMOLTW5w the decline in salmon. The number of young released to the ocean has N@l increased steadily since that time. As an example, coho smolt releases Pul!@Uc_ 1@;MOLITII increased from less than one million during the 1950s to 62 million in 30. 1981 (see Figure 52). An ever-increasing number of salmon smolts has had mixed results and has not always translated into an increased number of adults. On the one hand, chinook salmon have been generally stable or increasing from 1960 to 1982, although some (for example, V summer Columbia River chinook) have been on the decline. On the other 20 - hand, coho production illustrates a different trend, increasing from the early 1960s through the early 1970s and then declining from the mid-1970s until today (see Figure 53) (59). ^PULT C@DHO 0- YE^Jz@ OF, Az>e1L-7' R,67161" Aaafftd F- PAGIFIG MAPINE MHEMEZ COMMIUON 3b-ANNLOL REPOPT, 1983 Figure 52. Coho Salmon Hatchery Releases and Adult Abundance for the Period 1961-82. Far fewer adult coho salmon return to spawn than are released as smolts. The difference between total smolts and public smolts (smolts produced naturally or by public agency hatcheries) repre- sents private hatchery releases (salmon ranches) (data from 62). Several theories have been proposed to account for the recent coho declines. None has been proven and all are controversial. The Oregon Department of Fish and Wildlife has put forward several explanations in its 1982 Coho Salmon Plan (58). Two of them have received considerable attention recently from fisheries biologists and oceanographers. One theory involves the importance of ocean conditions to salmon Traditionally, the abundance of coho salmon was thought to be limited by the freshwater habitat. Streamflow, in particular, has been positively correlated with the catch of adults (53). Recent data, however, suggest that ocean conditions such as upwelling during the first year in the sea may be more important in determining year-class success and eventual adult abundance (53, 54, 88). (Factors such as ocean conditions are ref erred to as density-independent controls, since they operate regardless of the number of fish in the ocean). The other theory relates the increased number of young fish but low adult return to the ability of the ocean to provide food. Some fishery biologists feel that coho production has declined because too many smolts are being released by hatcheries, especially in years of low ocean production. (Regulating factors which vary proportionately with the number of fish living in the sea are collectively called density-dependent factors.) Figure 52 shows the dramatic increase in the number of young salmon released by Oregon's public hatcheries and salmon ranches Superimposed on this figure is the abundance of coho adults over the same period. The number of adult fish produced after 1975 has declined in spite of the continually increasing number of smolts release. This type of relationship could indicate that there is a finite limit to the number of salmon the ocean can support and that the limit may have been exceeded (47, 48). Such a limit is called the carrying capacity. The carrying capacity of the ocean is not fixed. Long-term changes have occurred in ocean conditions, including sea level rise and sea tem- perature increases associated with the most recent El Nino events. Such changes in the environmental conditions of the ocean may explain why salmon have been more abundant int he past (68). Moreover, natural salmon populations containted a combination of individual races that had adapted to various niches in the available habitat. Thus, ocean carrying capacity in the past could have been higher than today now that present populations include artificial production where ability to adapt to a wide variety of niches may be less than for natural production (56). It is likely that a combination of factors is causing the decline of coho salmon. The identity of these factors and their degree of influence cannot be ascertained withgout much more information. SOME FISH SPECIES OF MINOR COMMERCIAL IMPORTANCE OFF THE OREGON COAST (After Miller and Lee, 1972) CABEZON Scorpaenicthys marmoratus KELP GREENLING Hexagrammos decagrammus Ranges from Baja California to Sitka, Alaska. KELP GREENLING Hexagrammos decagrammus Length up to nearly 1 meter. Ranges from La Jolla, California, to Aleutian Islands, Alaska Found from shallow intertidal to 75 meters. Length up to 1/2 meter. Found from intertidal zone to 45 meters; common in kelp beds but taken in deeper waters over sandy bottoms. LING COD Ophiodon elongatus Ranges from Baja California to Kodiak Island, Alaska. Length up to slightly over 1 meter; weight varies from up to 41 pounds off California to over 100 pounds off British Columbia. Found at various depths by age: juveniles in shallow bays on sand and mud bottoms from beach to nearly 100 meters; adults from surface to 420 meters. SPINY DOGFISH Squalus acanthius SPINY DOGFISH Squalus acanthias ENGLISH SOLE Parophrys vetulus Ranges from central Baja California to Alaska. Ranges from Baja California to northwest Alaska. Length to 1 1/2 meters. Length up to 1/2 meter. Found from shallow waters to 360 meters. Found from 20 meters to 300 meters. REDTAIL SURFPERCH Amphistichus rhodoterus Ranges from Monterey Bay, California, to Vancouver Island, B.C. SURF SMELT Hypomesus pretiosus Length to 40 centimeters. Ranges from Long Beach, California, to Prince William Sound, BIG SKATE Raja binoculata Found from surface to 8 meters. Alaska. BIG SKATE Raja binoculata Length to 25 centimeters. Ranges from Baja California to Bering Sea. Spawns in surf in daytime. Length to 2 1/2 meters, but rarely over 2 meters. Found from 3 meters to slighty over 100 meters. 56 NEKTON COMMERCIAL AND RECREATIONAL FISHING: between the mouth of the Columbia River south to Tillamook Head and a peak in the cyclical productivity of shrimp and Dungeness crab, and Where the Fish Are and How We Know the Stonewall Bank-Heceta Bank areas off the central coast. favorable weather and ocean conditions for fishing (43). n ancient industry, the harvesting of fish stocks is still one of The commercial catch off Oregon is made up of many nekton species, as Recent declines in traditionally important fisheries such as salmon have the most important uses of the ocean. Yet basic data about fish well as several important benthic species (see "Benthos: The Seafloor" increased interest in the commercial harvest of alternative species. distribution and abundance is difficult for scientists to obtain. for a discussion of Dungeness crab, Tanner crab, pink shrimp and Squid, skate, northern anchovy, Pacific saury, sergestid shrimp, Pacific Fisheries biologists and oceanographers depend on catch weathervane scallops). This variety is reflected in the accompanying mackerel, and jack mackerel are abundant, but markets have not yet table, "Commercial Fish and Shellfish Landings in Oregon 1970-1983," been developed for these species. At present, many of these species data supplied by commercial fishermen because going to sea is expen- which lists all commercial fish catches from 1970 to 1983. On the basis of are hauled in with other commercial target species but are tossed back sive and making quantitative observations once there is difficult. Thus, pounds landed, however, rockfish, salmon, lingcod, Dover sole, and over the side. It has been estimated that these discarded species may commercial fishermen provide important information on the kinds of sablefish have been the most important. Pacific whiting, though not account for between one-third to one-half of the total commercial catch species caught in a particular area-their size, sex, age, and community landed in Oregon, has been important until recently as a foreign and (68). composition. U.S.-foreign joint-venture fishery. Several fish species important to commercial fishermen are also impor- Nevertheless, commercial fish catch data, though valuable, is used Most of the groundfish species caught in the commercial and recrea- tant to recreational fishermen as sport fish. Rockfish and salmon within limits by biologists. Catch statistics do not reveal information tional fisheries live over the continental shelf, although some are abun- dominate the ocean sport catch (see Figure 56), but other species about species not caught or individuals too small to be netted. Some dant over the continental slope (sablefish, Dover sole, rex sole, and some frequently sought include redtail surfperch and lingcod (25, 26). species may be fished with more intensity than other species, so catch rockfishes). Many of the species associated with the bottom exhibit P-E02ZAFIONAL 0CLAN 6ALMON CATCH 1@q66_1953 data may show a disproportionate amount of the target species or show distinct preferences for water depth (2) and bottom type-rock, sand, them in greater numbers in a particular area. Catch statistics reveal mud (12, 66). Figures 48, 49, and 50 map the commercial catch of three where fish are caught, not necessarily their distribution. species with differing environmental preferences over the continental Improvements in fishing technology have affected the catch data shelf and slope off Oregon. supplied to scientists. Larger boats with more powerful engines can stay Commercial landings for Oregon have varied greatly, from approximately at sea longer and range farther in search of fish. Improved nets increase 90 million pounds in 1973 to almost 84 million pounds in 1984 (see Table: the efficiency of the catch. Echo sounders are now used to locate fish, "Commercial Fish and Shellfish Landings in Oregon 1970-1983" and which appear as little dots on a screen. Infrared satellite images reveal Figure 55). The fluctuation in landings can be influenced by a variety of upwelling areas where fishing success could be higher. Together this factors, including abundance of fish, weather, market conditions, increased fishing power has changed the numbers and kinds of fish improvements in fishing gear, shifts in species targeted for harvesting, caught and thus the information available to biologists. and governmental regulations. An increase in landings during the mid- to Fishermen have long known that fish distribution usually coincides with late 1970s resulted from several factors, including an increase in the 1190 - specific environmental conditions to which a species has adapted. number of vessels (most of which were large trawlers) in the fishing fleet, Water temperature and salinity, depth, sediment type, and other bottom ....................... .............. conditions combine to create unique conditions attractive to certain fish. T0T4Z_ 17OUND-5 LANZ),-_O: Col@lvf,12CAZ- f-/,W AND 51-ILLLF1,3H _b& 67 6e &1 197.0 7/ 71- 7.@, 74 IF75 7& 77 7e 100 el 6> Many species have overlapping habitat requirements so that several fish types may inhabit a given area (see Figure 54). These areas of high fish Afft7- OPEWN OF-Dr F-15ti @ WIMLIFE, 19(53 concentration have been traditional fishing grounds, such as the area SURVIVAL IN THE OCEAN ishermen and biologists have often wondered why some 0 - fish species are abundant in some years and scarce in others. One approach to this problem has been to deter- IF mine the point in some animal's life history when it is most vulnerable (18, 11). The first months of life are a critical period in determining the abundance of an animal since the youngest ......... .. W JEE, stages of fish and invertebrates experience the highest rates of mortality. If larvae and juveniles experience favorable environmen- 00 0- tal conditions, then there will usually be a correspondingly higher number of mature adults available for a commercial or recreational fishery. .=t,- Survival through the first few months of life depends upon both physical and biological factors. Adequate supplies of food are central to survival. Off Oregon, upwelling produces phytoplankton 11" M74 1175 676 IM Me If7f IWO lfbl /fe.7- Ne) /W blooms which in turn provide many animals with food. In the Z0001- Aff.&- AL710N. 1?7e Y E, A F-_ absence of upwelling, not only is food less available and mortality _J 0,---rA FRCM QPX- DE.r FKSH@,WiLDUM increased, but individual growth is also slowed. The slower a Figure 54. Benthic Fish Assemblages on the Outer Figure 55. Twelve-Year Trend in Oregon Commercial species grows, the more time it is exposed to possible predation Continental Shelf and Slope off Northern Oregon. Landings. from larger individuals. An adequate food supply and the availabil- The distribution of fish species changes with depth. Rockfish are (ODF&W data). The increase in landings from 1976 to 1978 reflects ity of species to the fishery have been correlated with the intensity the most numerous fish on the upper continental slope, whereas increased fishing effort, favorable environmental conditions, and of upwelling (78, 28) and abundance of food such as pink shrimp rattails begin to dominate in deeper water and become the most peak cycles in the life history of key species. Catch statistics for (87,53). abundant fish below 1,000 meters. specific fish are shown by year in the accompanying table. 191vo REFERENCES 21. Hartt, A. C. 1980. Juvenile Salmonids in the Oceanic Ecosystem-The Critical First 41. Livingston, P. A. 1983. Food Habits of Pacific Whiting, Meriuccius productus, off the Summer: Pages 25-28 in W. McNeil and D. Himsworth, editors. Salmonid Ecosystems West Coast of North America, 1967 and 1980. Fishery Bulletin 81:629-636. of the North Pacific. Oregon State University Press, Corvallis, Oregon. 42. Loukashkin, A. S. 1970. On the Diet and Feeding Behavior of the Northern Anchovy, Note: References are cited in text by number. 22. Heg, R., and J. Van Hyning. 1951. Food of the Chinook and Silver Salmon Taken off the Engraulis mordax (Girard). Proceedings of the California Academy of Science, 1. AhIstrom, E. H., and H. D. Casey. 1956. Saury Distribution and Abundance, Pacific Oregon Coast. Fish Commission of Oregon Research Briefs 3:32-40. 37:419-458. Coast, 1950-55. U. S. Fish and Wildlife Service Special Science Report, Fish 190. 23. Hixon, R. F. 1983. Loligo opalescens. Pages 95-115 in Cephalopod Life Cycles, Vol. 1. 43. Lukas, G. 1985. Personal communication. Oregon Department of Fish and Wildlife. 2. Alton, M. S. 1972. Characteristics of the Demersal Fish Fauna Inhabiting the Outer Academic Press, London. Portland, Oregon. Continental Shelf and Slope off the Northern Oregon Coast. Pages 583-636 in A. T. 24. Holmberg, E. K., and W. G. Jones. 1954. Results of Sablefish Tagging Experiments in 44. MacCall, A. D., and G. D. Stauffer. 1983. Biology and Fishery Potential of Jack Mackerel Pruter and D. L. Alverson, editors. The Columbia River Estuary and Adjacent Waters: Washington, Oregon and California. Pacific Marine Fisheries Commission Bulletin (Trachurus symmetricus). California Cooperative Oceanic Fisheries Investigative Bioenvironmental Studies. University of Washington Press, Seattle, Washington. 3:103-119. Report 24:46-56. 3. Alton, M. S. and M. 0. Nelson. 1970. Food of Pacific Hake, Merluccius productus, in 25. Holliday, M. C., D. G. Deuel, and W. M. Scogin. 1984. Marine Recreational Fishery 45. MacGregor, J. 1966. Synopsis on the Biology of the Jack Mackerel (Trachurus Washington and Northern Oregon Coastal Waters. Pages 35-42 in Pacific Hake, U.S. Statistics Survey, Pacific Coast, 1979-1980. Current Fishery Statistics Number 8321. symmetricus). U.S. Fish and Wildlife Service Special Scientific Report, Fisheries 526. Fish and Wildlife Service Circular 332. National Marine Fisheries Service, Washington, D. C. 46. Mason, J. E. 1965. Salmon of the North Pacific Ocean-Part IX: Coho, Chinook and 4. Arthur, D. K. 1976. Food and Feeding of Larvae of Three Fishes Occurring in the 26. Holliday, M. C. 1984. Marine Recreational Fishery Statistics Survey, Pacific Coast, Masu Salmon in Offshore Waters. International North Pacific Fisheries Commission California Current, Sadinops sagax, Engraulis mordax, and Trachurus syurnmetricus. 1981-1982; Current Fishery Statistics Number 8323. National Marine Fisheries Service, Bulletin 16:41-73. Fisheries Bulletin 74:517-530. Washington, D. C. 47. McGie, A. M. 1981. Trends in Escapement and Production of Fall Chinook and Coho 5. Bailey, K. M., R. C. Francis, and P. R. Stevens. 1982. The Life History and Fishery of 27. Horn, M. H. 1980. Diversity and Ecological Roles of Noncommercial Fishes in California Salmon in Oregon. Oregon Dept. Fish and Wildlife Information Report 81-7. Pacific Whiting, Merluccius productus. California Cooperative Oceanic Fisheries Marine Habitats. California Cooperative Oceanic Fisheries Investigative Report 48. McGie, A. M. 1984. Evidence for Density Dependence among Coho Salmon Stocks in Investigative Report 23:81-98. 21:37-47. the Oregon Production Index Area: Pages 37-49 in W. G. Pearcy, editor. The Influence 6. Brock, V. 1940. Note on the Young Sablefish, Anoplopoma fimbria. Copeia 4:268-270. 28. Hyman, R. A., and A. V. Tyler. 1980. Environment and Cohort Strength of the Dover of Ocean Conditions on the Production of Salmonids in the North Pacific. Oregon State 7. Brodeur, R. D. 1983. Food Habits, Dietary Overlap and Gastric Evacuation Rates of Sole and English Sole. Transactions of the American Fisheries Society 109:54-70. University Sea Grant Publication ORESU-W-83-001, Corvallis, Oregon. Rockfishes (genus Sebastes): M.S. Thesis, Oregon State University, Corvallis, Oregon. 29. Inoue, M. S., and S. Hughes. 1971. Pacific Saury (Cololabis saira), a Review of Stocks, 49. Miles, E., et al. 1982. Atlas of Marine Use in the North Pacific Region. University of 8. Carlisle, J. 1971. Food of the Jack Mackerel, Trachurus symmetricus. California Fish Harvesting Techniques, Processing Methods and Markets: Eng. Exper. Sta. Bull. 43, California Press, Berkeley, California, and Game 57:205-208. Oregon State University, Corvallis, Oregon. 50. Miller, P. J., and R. N. Lee. 1972. Guide to the Coastal Marine Fishes of California. 9. Clemens, H. B. 1961. The Migration, Age, and Growth of Pacific Albacore. California 30. Jefferts, K. 1983. Zoogeography and Systematics of Cephalopods of the Northeast California Fish and Game Bulletin 157. Dept. Fish & Game Bull. 115:1-128. Pacific Ocean. PhD Thesis, Oregon State University, Corvallis, Oregon. 51. Morejohn, G. V., J. T. Harvey, and L. T. Krasnow. 1978. The Importance @f Loligo 10. Clemens, H. B., and R. A. Iselin. 1963. Food of Pacific Albacore in the California Fishery 31. Johnson, J. H. 1962. Sea Temperatures and the Availability of Albacore off the Coasts opalescens in the Food Web of Marine Vertebrates in Monterey Bay, California. (1955-1961). Pages 1523-1535 in H. Rosa, editor. Proceedings of the World Scientific of Oregon and Washington. Trans. American Fisheries Society 91:269-274. California Fish and Game Bulletin 169: 67-98. Meetings on the Biology of Tunas and Related Species, F. A. 0. Report No. 6. 32. Judkins, D. C., and A. Fleminger. 1972. Comparison of Gut Contents of Sergestes 52. Netboy, A. 1980. The Columbia River Salmon and Steelhead Trout, Their Fight for 11. Cushing, D. *H. and J. G. K. Harris. 1973. Stock and Recruitment and the Problem of similis Obtained from Net Collections and Albacore Stomachs. Fishery Bulletin Survival. University of Washington Press, Seattle, Washington. Density Dependence: Rapp. Process-Verb. Cons. int. Explor. Mer. 164:142-155. 70:217-223, 53. Nickelson, T. E. 1983. The Influence of Ocean Conditions on Abundance of Coho 12. Demory, R. L. 1975. Informational Report-Dover Sole: Oregon Department of Fish and 33. Kaiser, R. 1985. Personal communication. Oregon Department of Fish and Wildlife. Salmon (Oncorhynchus kisutch) in the Oregon Production Area. Oregon Dept. Fish and Wildlife Informational Report 75-4. Portland, Oregon. Newport, Oregon. Wildlife Information Report 83-6. 13. Fitch, J. 1956. Jack Mackerel: California Marine Research Commission. Pages 27-28 in 34. Karpov, K. A., and G. M. Cailliet. 1979. Prey Composition of the Market Squid, Loligo 54. Nickelson, T. E., and J. A. Lichatowich. 1984. The Influence of the Marine Environment California Cooperative Oceanic Fisheries Investigative Progress Report. April 1, 1955 opalescens Berry, in Relation to Depth and Location of Capture, Size of Squid and Sex on the Interannual Variation in Coho Abundance: An Overview. Pages 24-36 in W. G. to June 30, 1956. of Spawning Squid. California Cooperative Oceanic Fisheries Investigative Report Pearcy, editor. The Influence on Ocean Conditions on the Production of Salmonids in 14. Gabriel, W. L., and W.G. Pearcy. 1981. Feeding Selectivity of Dover sole, Microstomus 20:51-57. The North Pacific.Oregon State University Sea Grant Publication ORESU-W-83-001, pacificus, off Oregon. Fishery Bulletin 79:749-763. 35. Kodolov, L.S. 1963. Reproduction of the Sablefish (Anoplopoma fimbria [Pall.]). Corvallis, Oregon. 15. Godfrey, H., K. A. Henry, and S. Machidori. 1975. Distribution and Abundance of Coho Problems in Ichthyology 8:531-535. 55. Omori, M., A. Kawamura, and Y. Aizawa, 1972. Sergestes similis Hansen, Its Distribu- Salmon in Offshore Waters of the North Pacific Ocean. International North Pacific 36. Kramer, D., and P. Smith. 1970. Seasonal and Geographic Characteristics of Fishery tion and Importance as Food of Fin and Sei Whales in the North Pacific Ocean. Pages Fisheries Commission, Bulletin 31. Resources, California Current Region-1. Jack Mackerel. Commercial Fisheries Review 373-391 in A. Y. Takenouti, editor. Biological Oceanography of the Northern North 16. Gotshall D. W. 1969. Stomach Contents of Pacific Hake and Arrowtooth Flounder from 32:27-31, Pacific Ocean. Idemitsa Shoten, Tokyo, Japan. Northern California. California Fish and Game 55:75-82. 37. Laroche, J. L,, and S. L. Richardson. 1981. Reproduction of Northern Anchovy, 56. Oregon Department of Fish and Wildlife. 1985. Salmon Management Group, comments 17. Grinols, R. B., and C. D. Gill. 1968 '. Feeding Behavior of Three Oceanic Fishes Engraulis mordax, off Oregon and Washington. Fisheries Bulletin 78:603-618. on draft of Oceanbook. duction (Oncorhynchus kisutch, Trachurus symmetricus, and Anoplopoma fimbria) from the 38. Laurs, R. M. 1983. The North Pacific Albacore-An Important Visitor to California 57. Oregon Department of Fish and Wildlife. 1982a. Comprehensive Plan for Pro Northeastern Pacific. Journal of the Fisheries Research Board of Canada 25:825-827. Current Waters, California Cooperative Oceanic Fisheries Investigative Report and Management of Oregon's Anadromous Salmon and Trout; Part I-General 18. Gulland, J. A. 1965. Survival of the Youngest Stages of Fish, and its Relation to Year- 24:99-106. Considerations. Oregon Dept. Fish and Wildlife, Portland, Oregon. Class Strength. International Commission on Northwest Atlantic Fisheries, Special 39. Laurs, R. M., and R. J. Lynn. 1977. Seasonal Migration of North Pacific Albacore, 58. Oregon Department of Fish and Wildlife. 1982b. Comprehensive Plan for Production Publication No. 6. Thunnus alalunga, into North American Coastal Waters: Distribution, Relative Abun- and Management of Oregon's Anadromous Salmon and Trout; Part fl- .Coho Salmon 19. Hagerman, F. B. 1952. The Biology of the Dover Sole, Microstomus pacificus dance, and Association with Transition Zone Waters. Fishery Bulletin 75:795-821. Plan. Oregon Dept. Fish and Wildlife, Portland, Oregon. (Lockington). California Dept. Fish and Game Bulletin 85:1-48. 40. Levy, D. A. 1984. Variations in Estuarine Utilization among Juvenile Chinook Salmon 59. Pacific Fishery Management Council. 1984. Review of the 1983 Ocean Salmon 20. Hart, J. L. 1975. Pacific Fishes of Canada. Fisheries Research Board of Canada Bulletin Populations. Pages 297-302 in W. G. Pearcy, editor, The Influence of Ocean Conditions Fisheries and Status of Stocks and Management Goals for the 1984 Salmon Season off 180. on the Production of Salmonids in the North Pacific. Oregon State University Sea Grant the Coasts of California, Oregon, and Washington. Pacific Fishery Management Publication ORESU-W-83-001, Corvallis, Oregon. Council, Portland, Oregon. no U0 Hmum 60. Pacific Fishery Management Council. 1982. Pacific Coast Groundfish Plan; Final 77. Peterson, W. T., R. D. Brodeur, and W. G. Pearcy. 1982. Food Habits of Juvenile Salmon. Fishery Management Plan and Supplemental Environmental Statement for the Wash- in the Oregon Coastal Zone, June 1979. Fishery Bulletin 80:841-851. ington, Oregon, and California Groundfish Fishery. Pacific Fishery Management 78. Peterson, W. T., and C. B. Miller. 1976. Zooplankton Along the Continental Shelf off Council, Portland, Oregon. Newport, Oregon 1969-1972. Sea Grant Publication ORESU-T-72-002, Oregon State 61. Pacific Fishery Management Council. 1979a. Draft Environmental Impact Statement University, Corvallis, Oregon. and Fishery Management Plan for the Jack Mackerel Fishery. Pacific Fishery Manage- 79. Phillips, J. B., and S. Imamura. 1954. The Sablefish Fishery of California. Pacific Marine ment Council, Portland, Oregon. Fisheries Commission Bulletin 3:5-38. 62. Pacific Marine Fisheries Commission. 1984. 36th Annual Report of the Pacific Marine 80. Prakash, A. 1962. Seasonal Changes in Feeding of Coho and Chinook (Spring) Salmon Fisheries Commission for the Year 1983. Portland, Oregon. in Southern British Columbia Waters. Journal of the Fisheries Research Board of 63. Pearcy, W. G. 1972. Distribution and Ecology of Ocean Animals off Oregon: Pages Canada 19:851-866. 351-370 in A. T. Pruter and D. L. Alverson, editors. The Columbia River Estuary and 81. Pruter, A. T. 1972. Review of Commercial Fisheries in the Columbia River and in Adjacent Waters: Bioenvironmental Studies. University of Washington Press, Seattle, Contiguous Ocean Waters. Pages 81-122 in A. T. Pruter and D. L. Alverson, editors. The Washington. Columbia River Estuary and Adjacent Waters: Bioenvironmental Studies. University of 64. Pearcy, W. G. 1973. Albacore Oceanography off Oregon-1979. Fishery Bulletin Washington Press, Seattle, Washington. 71:489-504. 82. Reimers, P. E. 19@3. The Length of Residence of Juvenile Fall Chinook Salmon in Sixes 65. Pearcy, W. G. 1976. Seasonal and Inshore-Off shore Variations in the Standing Stocks River, Oregon. Fish Commission of Oregon Research Report 4:3-42. of Micronekton and Macrozooplankton off Oregon. Fishery Bulletin 74:70-80. 83. Reimers, P. E., and R. Loeffel. 1967. The Length of Residence of Juvenile Chinook 66. Pearcy, W. G. 1978. Distribution and Abundance of Small Flatfishes and Other Salmon in Selected Columbia River Tributaries. Fish Commission of Oregon Research Demersal Fishes in a Region of Diverse Sediments and Bathymetry off Oregon. Fishery Briefs 13:5-19. Bulletin 76:629-640. 84. Richardson, S. L. 1973. Abundance and Distribution of Larval Fishes in Waters off 67. Pearcy, W. G. 1984. Where Do All the Coho Go? The Biology of Juvenile Coho Salmon Oregon, May-October 1969, with Special Emphasis on the Northern Anchovy, off the Coasts of Oregon and Washington. Pages 50-60 in W. G. Pearcy, editor. The Engraulis mordax. Fishery Bulletin 71:697-711. Influence of Ocean Conditions on the Production of Salmonids in the North Pacific. 85. Richardson, S. L. 1981. Spawning Biomass and Early Life of Northern Anchovy, Oregon State University Sea Grant Publication ORESU-W-83-001, Corvallis, Oregon. Engraulis mordax, in the Northern Subpopulation off Oregon and Washington. Fishery 68. Pearcy, W. G. 1985. Personal communication, College of Oceanography, Oregon State Bulletin 78:855-875. University, Corvallis, Oregon. 86. Richardson, S. L., and W. G. Pearcy. 1977. Coastal and Oceanic Fish Larvae in an Area 69. Pearcy, W. G., and C. A. Forss. 1966. Depth Distribution of Ocean Shrimps Pecapoda of Upwelling off Yaquina Bay, Oregon. Fishery Bulletin 75:125-145. natantia) off Oregon. Journal of the Fisheries Research Board of Canada 23:1135-1143. 87. Rothlisberg, P. C., and C.B. Miller. 1983. Factors Affecting the Distribution, Abundance, 70. Pearcy, W. G., and J. W. Ambler. 1974. Food Habits of Deep-sea Macrourid Fishes off and Survival of Pandalusjordani (Decapoda, Pandalidae) Larvae off the Oregon Coast. the Oregon Coast. Deep-sea Research 21:745-759. Fishery Bulletin 81:455-472. 71. Pearcy, W. G., and D. Hancock. 1978. Feeding Habits of the Dover Sole, Microstomus 88. Scarnecchia, D. L. 1981. Effects of Strearnflow and Upwelling on Yield of Wild Coho pacificus; Rex sole, Glyptocephalus zachirus; Slender sole, Lyopsetta exilis; and Salmon (Oncorhynchus kisutch) in Oregon. Can. J. Fish. Aquat. Sci. 38:471-475. Pacific San Dab, Citharicthys soridus; in a Region of Diverse Sediments and Bathyme- 89. Stander, J. M., and R. L. Holton. 1978. Oregon and Offshore Oik Sea Grant Publication try off Oregon. Fishery Bulletin 76:641-651. ORESU-T-78-004, Oregon State University, Corvallis, Oregon. 72. Pearcy, W. G., and R.M. Laurs. 1966. Vertical Migration and Distribution of Mesopelagic 90. Stein, D. L. 1980. Description and Occurrence of Macrourid Larvae and Juveniles in the Fishes off Oregon. Deep-sea Research 13:153-165. Northeast Pacific Ocean off Oregon, U.S.A.. Deep-sea Research 27A:889-900. 73. Pearcy, W. G., E. E. Krygier, R. Mesecar, and F. Ramsey. 1977. Vertical Distribution and 91. Stein, D. L., and W. G. Pearcy. 1982. Aspects of Reproduction, Early Life History, and Migration of Oceanic Micronekton off Oregon. Deep-sea Research 24:223-245. Biology of Macrourid Fishes off Oregon, U.S.A.. Deep-sea Research 29:1313-1329. 74. Pearcy, W. G., M. J. Hosie, and S. L. Richardson. 1977. Distribution and Duration of 92. Sund, P. N., B. Blackburn, and F. Williams. 1981. Tunas and their Environment in the Pelagic Life of Larvae of Dover Sole, Microstomus pacificus; Rex Sole, Glyptocephalus Pacific Ocean: A Review. Oceanography and Marine Biology Annual Review zachirus; and Petrale Sole, Eopsetta jordani, in Waters off Oregon. Fishery Bulletin 19:443-512. 75:173-183. 93. Tyler, H. R., and W. G. Pearcy. 1975. The Feeding Habits of Three Species of 75. Pearcy, W. G., H. V. Lorz, and W. Peterson. 1979. Comparison of the Feeding Habits of Lanternfishes (Family Myctophidae) off Oregon, USA.. Marine Biology 32:7-11. Migratory and Nonmigratory Stenobrachius leucopsarus (Myctophidae). Marine Biol- 94. Wiens, J. A., and J. M. Scott. 1975. Model Estimation of Energy Flow in Oregon Coastal ogy 5 1: 1 -6. Seabird Populations. Condor 77:439-452. 76. Pearcy, W. G., D. L. Stein, and R. S. Carney. 1982. The Deep Sea Benthic Fish Fauna of the Northeast Pacific Ocean on Cascadia and Tufts Abyssal Plains and Adjoining Continental Slopes. Biological Oceanography 1:375-428. nQ CHAPTER SIX BEHUM(0.2 The Sea Floor INTRODUCTION ar below the wave-tossed ocean surface, the floor of the ocean A small proportion of the sea bottom consists of rocky habitat around Size Range of Benthic Animals provides a surprisingly diverse habitat for marine life. Referred nearshore sea stacks, banks of the continental shelf, and recently to as the benthos, this bottom environment includes the rocky erupted volcanic rocks on the midocean ridges. These rocky areas also ottom-dwelling animals are frequently grouped in three size IF interticlal zone near the coast, the gently sloping mud- and sand- provide habitat different from the sediment-covered bottom. categories: macrofauna, meiofauna, and microfauna (see Fig- covered flats of the continental shelf, and the steeply dipping, mud- Nearshore, the ocean floor of the continental shelf is affected by a ure 58). The largest are the macrofauna, those organisms long covered continental slope leading down to the deep ocean abyssal constantly changing physical environment. Bottom-dwelling species 12 enough to be retained on a seive with a mesh of 0.5 millimeters. plains. must contend with wave action, currents, turbidity, and daily and This group is perhaps the best known since their size makes them easy The ocean floor is home to nearly all major invertebrate groups (animals seasonal changes in light and temperature. In addition, marine life of the to sample and sort. Some of these macrofauna are gastronomic deli- without backbones) but only a fraction of them-such as clams, crabs, nearshore intertidal zones has adapted to alternating periods of cacies of the sea world: crabs, lobsters, oysters, and sea urchin roe. and scallops-are harvested by humans. Far more abundant off Oregon exposure to air and tidal inundation. are nematodes, polychaetes (marine worms), molluscs (snails and Bottom-dwelling creatures have developed a variety of methods to take clams), crustaceans (shrimp, copepods, amphipods, isopods), and advantage of the diversity in bottom habitats and environmental condi- echinoderms (sea urchins, starfish, brittle stars). tions. Some, like the giant kelp and barnacles, live attached to a firm Life on the seafloor also includes a variety of vertebrate animals. Bottom- surface. Others, like clams and worms, burrow freely through soft dwelling fishes, such as sole, flounder, skate and cod, inhabit this sediments or, like crabs and sea cucumbers, roam the sea floor. Those benthic environment. Several of these benthic fishes are described in benthic species living on the surface are referred to as epifauna; infauna refers to animals that conceal themselves below the surface (see Figure Chapter Five, "Nekton: The Swimmers." In addition to the animal life 10 found on the ocean bottom, a few marine plants live attached to the 57). seafloor (see sidebar: "Seaweeds"). This chapter of the Oceanbook describes general characteristics of benthic organisms, their diversity, habitat preferences, feeding, and life MM07AUN4 MVDFAUNA MAU-CFAUNA cycle. Several species important to commercial and recreational use off L /'-'/C AN1,V4Z-S the Oregon coast are highlighted. In addition, the unique benthic life of 517-E- C,47ZC7CP-165 OF 5,E1VT deep-sea hydrothermal vents is discussed. Figure 58. Size Categories of Benthic Animals Benthic animals are classified into three major groups based on 1- A UNA size. Representative examples within each group are shown. The BENTHIC CHARACTERISTICS scale of the drawings is approximate. Environmental Opportunity . ........ ediments covering the seafloor vary in composition. This diver Meiofauna are small organisms (retained on sieves of 0.063 to 0.5 sity creates a variety of environmental opportunities for benthic millimeters) that cannot be seen without the aid of a microscope and are organisms. Mud is composed of extremely fine particles of _40 difficult to count and identify. Primarily multicellular animals, meiofauna //Y@ IVA sediment which pack tightly together. Sand particles, on the live in the spaces between sediment particles and include free-living other hand, are larger and leave larger spaces between them. Mixtures nematodes (round worms) and copepods as well as the younger, smaller of sand and mud yield a variety of grain spaces. Organic material may be life stages of many macrofaunal animals. present on the ocean floor and mixed into the sediment spaces in Microfauna, such as bacteria and protozoans, are the smallest forms of varying quantities. Many benthic animals are very small and burrow into Figure 57. Examples of Epifauna and Infauna life (less than 0.063 millimeters). Little is known about the role of this the sediments. They have particular likes and dislikes about the kinds of Benthic animals living on the surface of the ocean floor are referred group in the marine ecosystem, though bacteria are important in sediments in which they will live. Thus, just as the composition of the to as epitauna. These include crabs, brittle stars, and scallops. breaking down organic compounds and returning nutrients to the water. seafloor itself changes over an area, so too does the community of Those which live below the surface, such as clams and burrowing in a form usable by other species. animals populating that area. worms, are known as infauna. BEHIrmoo Food Sources and Feeding Methods ost of the seafloor lies below the euphotic zone. As a result, bottom-living animals ultimately rely upon food falling from the ocean's upper layers or brought in by ocean currents (see Figure 59.). (Animals living around deep-sea hydrother- mal vents are an exception to this generalization and are discussed elsewhere in this chapter.) Z3fN77'1C FOOZ) 50UP-CE,5 SEAWEEDS' FSL IlArrElp_ arine algae include not only microscopic floating plants, but PLAtV r large attached species as well. Because plants depend on 4,Q115 rA ed:AN the sun's energy, these attached seaweeds are confined to relatively shallow waters nearshore where sunlight pene trates the water to the bottom or where the seaweed leaves can float in the sunlight while the plant is anchored to the dimly lit bottom. It E. Marine algae can be distinguished in part by their pigmentation, hence the names red algae, green algae, and brown algae. Most of the large seaweeds belong to the brown algae group and frequently form dense beds around rocky outcrops. A Seaweeds contribute little to the overall production of food on the a .. .... .... "4 continental shelf or waters farther offshore, but can be a factor in the high productivity of coastal areas. Off central and southern California, . . ........ seaweed is particularly important in the diet of sea urchins, which in turn are a major food source for sea otters. The bladder or bull kelp, Nereocystis luetkeana, the most common large Figure 59. Benthic Food Sources kelp in Oregon, serves as a particularly important habitat for many Benthic animals depend on a slow, sparse rain of organic debris species of coastal fish and invertebrates. A branched "holdfast" drifting to the bottom from the surface layers. This debris ranges anchors it to the bottom and a long stalk leads to a bulbous, gas-filled from microscopic particles to entire fish carcasses. float at the surface (see Figure 60). Attached to this bulb are four broad leaves which capture solar energy as they float just below the surface. Bull kelp may grow to 20 meters (more than 60 feet) and may have leaves The amount of organic material reaching the bottom is greater near the 3 meters long. coast than at distances farther from shore. Two important factors contribute to this: higher phytoplankton production in the nearshore Although very numerous, Nereocystis beds are usually small and vary surface layer and a shorter journey downward through the water column. through time in size and position (24). Some beds temporarily disappear only to be re-established several years later. This huge kelp is an annual, Thus, more downward-drifting food reaches the bottom before being (Uptzo,,@t_) intercepted and consumed. putting on all of its growth during the spring and summer. Following the winter die-off, many of these plants are washed onto the beach. Feeding habits of benthic animals vary greatly and generally relate to the Nereocystis reproduces asexually by microscopic spores. These spores type of sediment in which a species is found. Common feeding modes live through the winter to produce the next generation of kelp in the are filter feeding, deposit feeding, and predation. Filter or suspension spring (14). Figure 60. Bull Kelp feeding is most prevalent in nearshore, sandy environments where food Another large brown algae, the California giant kelp, Macrocystis integ- The leaves of the bull kelp are kept afloat at the surface by a is abundant. Scallops and mussels remove food particles from the water rifolia, a perennial, is of commercial importance in southern California. It bulbous, gas-filled float. A tough but flexible stalk terminates in a by pumping water past filtering mechanisms which extract small plant is found in Oregon only off Simpson Reef at Cape Arago just south of the "hold-fast, " which anchors the plant to the bottom. Piles of bull and animal plankton. entrance to Coos Bay (24). kelp, coiled like bull whips, litter Oregon beaches after a storm. Deposit feeders, which prefer fine muddy sediments rich in organic material, have developed several methods of recovering detritus as they roam the ocean bottom. Some, like shrimp, swim just above the bottom and make short excursions to the bottom to feed. Others, such as brittle stars and isopods, ingest the sediment particles around them, gleaning the organic detritus, Some burrowing clams use siphons to scoop up surface deposits. Benthic predators, such as the voracious crab, actively search out and prey upon other benthic animals (8). Ott DIENW010 Life Cycle and Reproduction Distribution of Benthic Animals Ithough most adult benthic animals live in a relatively cold Ithough relatively few studies have been conducted on the environment, the life cycle of many benthic organisms includes benthic fauna of the continental margin west of Oregon, it is a planktonic larval stage which takes advantage of higher known that species composition changes with depths and with temperatures and food available at the surface during this sediment characteristics. In very shallow water with sandy A "NEW" BENTHOS: critical nursery period (8). In many species, the release of larvae appears bottoms, filter-feeding amphipods, nuclibranchs, and gastropods domi- Deep Ocean Ridges and Hydro- to be timed to the burst of phytoplankton production, important for nate benthic infaunal communities. In the deeper water, shrimp and larvae that rely on this food resource. Crustaceans, molluscs, echi- urchins are more abundant. On the muddy bottoms of the mid- and outer thermal Vents noderms, and polychaete worms are among the many invertebrate continental shelf, deposit-feeding polychaete worms prevail (17). groups whose species may reproduce using a drifting larval stage. At Organisms of the deep ocean basins have adapted to a fairly stable set ince the discovery in 1977 of oceanic spreading centers the end of the planktonic phase, larvae settle to the bottom and select a of environmental conditions different from that of the continental margin. and hydrothermal vents, the unique biological commu- place to live. These organisms undergo a complex metamorphosis in In this dark, cold, high-pressure environment, food drifting downward to nities associated with them have been the subject of passing from a pelagic habitat to a bottom-dwelling existence. deep-sea communities is scarce. Food items can range in size from research by marine scientists (see also Chapter Two, minute particles of organic material absorbed onto sediment grains to "Geology: The Rocks"). Findings from this research have revealed the massive carcass of a whale. Accordingly, the numbers of deep-sea insights into biological processes and forms of life previously benthic animals and their growth rates are very low when compared to unknown on modern-day earth. Animals living in these zones do data from the continental shelf, yet the diversity of species living there is not depend upon the energy of sunlight and primary production by extremely high. Collections of several thousand macrobenthic animals plants for food. Instead, in a process called chemosynthesis, from these deep waters typically will contain 200 to 300 different species bacteria use the chemical energy contained in inorganic chemicals (13). to convert carbon dioxide into organic compounds. Bacteria have thus replaced plants as the primary producers in these vent Benthic animals found at water depths of 3,000 meters on the Cascadia ecosystems. Plain typify the life on many deep-sea plains adjacent to continental land masses. Of the larger burrowing animals, polychaete worms make up In some cases the bacteria live within the bodies of animals which the majority of samples collected, while crustaceans are the second take advantage of the chemosynthetic ability of the bacteria. For most abundant group. Sea cucumbers, brittle stars, and amphipods are example, vestimentiferan tube worms which are frequently seen very close to vents lack a digestive tract. This vent water contains the most frequently collected surface animals (1, 4, 5, 6, 7, 9, 12, 20, 23). reduced sulfur, oxygen, and carbon dioxide and is ingested by the No data on meiobenthos exist. tube worm. The bacteria within the gut of the tube worm then Beyond the Gorda and Juan cle Fuca ridges lies the deeper (over 3,200 produce nutritious organic compounds usable by their host. Mti (A rnwx) meters) Tufts Abyssal Plain. Studies show that whereas the number of Marine biologists studying these vents have catalogued previously larger infauna on the Tufts is roughly equivalent to that of the Cascadia unknown species of marine life living near them, including mussels, (A) Z-Off-A (E@) Alf-q,4 L_ OP-5 Basin, the biomass is only half as large, clams, limpets, polychaete worms, snails, barnacles, leeches, and copepods. Although a large number of organisms are found around the hydrothermal vents, the diversity of species is much lower than in other deep-sea habitats. Furthermore, the animals living in vent communities are actually different from those of surrounding deep- Figure 61. Planktonic Stages of the Dungeness crab water areas. Rather than growing very slowly and living for up to Crab zoea (A) undergo five molts before emerging into the mega- one hundred years or more as other deep-sea organisms have lops stage (B) and then spend approximately four months living in been shown to do, vent organisms seem to mature rapidly and the water column before they settle to the seafloor. (Figure adapted reproduce on a time scale of less than 10 years (111). from Reilly, 1983.) Hydrothermal vent communities are known to exist at several locations on the Juan cle Fuca Ridge and are suspected to exist on the Gorda Ridge. Recent dives of the research submersible Alvin For the tiny larvae, survival in the ocean is precarious and the chances of have revealed that the most abundant organisms of the Juan cle reaching maturity and colonizing a suitable area are slight. Larvae Fuca vent system are vestimentiferan worms, limpets, and poly- provide food for many larger organisms and suffer immense mortality chaete worms, all of which live on the sulfide chimney deposits of from predators, including all filter-feeding animals which consume large active vents. The composition of animal communities changes very quantities of pelagic larvae. In addition, some larvae may be carried far rapidly only a short distance away from the subsea oases created offshore by the currents and never find a suitable habitat. To overcome by the food available from the hydrothermal vents. Animal abun- these odds and ensure species survival, females of many species dance decreases to the normal low levels found in the deep sea release several thousands eggs each season. with only an occasional sponge or sea anemone seen attached to the bottom. Not all benthic organisms, however, have a pelagic larval stage. Some crustaceans, including amphipods, have brood pouches between their limbs, where the larvae are protected after they hatch. Other benthic larvae develop directly on the bottom. Although scientists know that such direct development occurs in other areas, research off Oregon is lacking. IMPORTANT COMMERCIAL BENTHIC SPECIES Benthic invertebrates are of major importance to Oregon's commercial fishing industry. However, because these benthic animals lack the mobility of the free-swimming vertebrate fish, they are easily harvested and thus are vulnerable to fishing pressure. The life history of several important benthic species is discussed in the following section. DUNGENESS CRAB Cancer magister Range. The Dungeness crab ranges from Baja California to Alaska in bays and shallow coastal water to a depth of 90 meters, preferring sandy or muddy-sand bottoms, but it can be foun on almost any type of substrate (18). Distribution. Dungeness crabs tend to move seasonally from shallow water in summer to deeper water in winter. Reproduction. Dungeness crabs mate in the spring. The female stores the sperm within her body until spawning, which takes place off Oregon from October to March (31). Eggs hatch and pelagic larvae are released during the winter. Throughout the next four months, while the larvae live as zooplankton, they undergo several transformations (see Figure 61) (15). Pelagic larvae are found up to 90 kilometers off the Oregon coast (15). Trophic Relationships. Dungeness crabs eat a wide variety of food. Examination of stomach contents shows that they consume crustaceans, clams, fishes, snails, and polychaete worms (3, 10). Planktonic crab larvae are eaten by juvenile coho and chinook salmon and rockfishes (see also Figure 3 in Chapter One)(25). Adult Dungeness crabs are preyed upon by lincod, wolf-eels, halibut, and rockfish (31). Fishery. The commercial landings of Dungeness crab fluctuate greatly over time. Indeed, catch statistics show an 11-year cycle in the abundance of crabs (2). Large numbers of Dungeness crabs were caught in 1956-57, 1967-68, and 1976-77 (see Figure 62). Dungeness crabs are harvested using baited traps. All nearshore Oregon waters less than 50 fathoms are fished except for one area near Cascade Head (see Figue 63). 66 BENTHOS PINK SHRIMP Pandalus jordani Range. Oregon pink shrimp are found along the west coast of North America. Off the Oregon coast they live in water 70-180 meters deep over muddy-sand bottoms. (26). Distribution and Vertical Migration. Pink shrimp spend the daylight hours on the bottom and then migrate into the water column at night (19). Reproduction. Pink shrimp are males for the first year of sexual maturity and then transform into females. The transformation is completed after the shrimp reach two and one-half years of age. Females carry their eggs in brood pouches between October and January; eggs hatch in late winter. From the eggs come planktonic larvae, which are most abundant on the inner shelf in February and March. As the larvae grow, they move further westward so that by June, late-stage larvae and young juveniles may be found 15 to 30 miles offshore. After settling to the seafloor, juveniles live in the same locations as the adults rather than seeking out separate nursery areas (16). Tropic Relationships. The food habits of pink shrimp are poorly known but observations show that adults found in water column at night eat euphausiids and copepods whereas those on the bottom feed on small benthic animals and detritus (19). Fish such as Pacific whiting eat pink shrimp and may strongly effect shrimp abundance (27). Fishery. The fishery for pink shrimp began prior to 1955, through gear restrictions and hand-picking costs hindered this effort. Legalization of the shrimp trawl fishery in the Gulf of Mexico and the development of the shrimp-packing machine allowed the industry to grow after 1957 (28). Shrimp landings increased steadily until they reached a peak harvest of 55 million pounds in 1977. Survival of shrimp is linked to upwelling; thus, the catch of shrimp increases as upwelling increases (27). Locations of commercial shrimp beds are illustrated in Figure 64. WEATHERVANE SCALLOP Pecten caurinus TANNER CRAB Chionoecetes tanneri Distribution. Weathervane scallops are found along the Oregon coast at Distribution. Off Oregon, Tanner crabs are found on the continental depths of from 90 to 120 meters (30). Distinct beds of scallops occur off slope at depths of from 500 to 1,920 meters. Adults are most frequently Coos Bay, the Siuslaw River, Yaquina Head, Cape Kiwanda, and encountered between 500 and 777 meters and juveniles are usually Tillamook Head, although the locations ofthese beds may shift from year caught between 640 and 1,554 meters (22). Adult males are normally to year (30). found at shallower depths than adult females. Reproduction. Weathervane scallops spawn from February through Reproduction. During winter, the male poplation makes a spawning July. The larvae are planktonic for a four- to six-week period. migration downward toward the females. Females carry fertilized eggs from spring to late winter, at which time the larvae hatch. Following Fishery. Surveys of the Oregon coast during the 1960s revealed the maturation within the plankton, young Tanner crabs settle to the bottom presence of weathervane scallops in commercial quantities, but Oregon in deep water. As they come to grow, they move into shallower water scallops remained unexploited until 1981, when several vessels landed and eventually join the adult population. large catches at Coos Bay. These beds were dominated by a single-year class (1975), indicating reproductiver failure for the period 1976 to 1980. Fishery. The Tanner crab is a deep-water species which may be within six months, most known scallop beds had been harvesed. Only a sufficiently abundant off Oregon to support a commercial fishery (21, few vessels continu to fish for scallops. 22). Other species of Chionocetes are fished off Japan and Alaska and in The Atlantic. Figure 63. Pik Shrimp Commercial Catch Areas off the Oregon Coast Figure 64. Thirty-Year Trends in Dungeness Crab Landings The upper figure shows total landings of Dungeness crab for the Pacific region (including Canada). A distinct 11-year cycle in crab abundance is visible. The lower figure shows the landings in Oregon for the same period. BENTHOS 67 REFERENCES 21. Pereyra, W, T. 1967. Tanner Crab-An Untapped Pacific Resource. National Fisher- man 48(4):16A. Note: References are cited in text by number. References marked with an asterisk (*) are 22. Pereyra, W. T. 1972. Bathymetric and Seasonal Abundance and General Ecology of the Tanner Crab, Chionoecetes tananeri Rathbun (Brachyura: Majidae), off the Northern recommended because they are comprehensive, easily understood and accessible. Oregon Coast. Pages 538-582 in A. T. Pruter and D. L. Alverson, editors. The Columbia 1 .Alton, M. S. 1972. Characteristics of the Demersal Fish Fauna Inhabiting the Outer River Estuary and Adjacent Waters: Bioenvironmental Studies, University of Wash- Continental Shelf and Slope off the Northern Oregon Coast: Pages 583-636 in A. T. ington Press, Seattle, Washington. Pruter and D. L. Alverson, editors. The Columbia River Estuary and Adjacent Waters: 23. Pereyra, W. T., and M. S. Alton. 1972. Distribution and Relative Abundance of Bioenvironmental Studies, University of Washington Press, Seattle, Washington. Invertebrates off the Northern Oregon Coast. Pages 444-474 in A. T. Pruter and D. L. 2. Botsford, L. W., R. D. Methot, and J. E. Wilen. 1982. Cycle Covariation in the California Alverson, editors. The Columbia River Estuary and Adjacent Waters: Bioenvironmental King Salmon, Oncorhynchus tshawytscha, Silver Salmon, 0. kisutch, Dungeness Crab, Studies. University of Washington Press, Seattle, Washington. Cancer magister Fisheries. Fishery Bulletin 80:791-802. 24. Phinney, H. K. 1977. The Macrophytic Algae of Oregon. Pages 93-138 in R. Krauss, 3. Butler, T. H. 1954. Food of the Commercial Crab in the Queen Charlotte Island Region. editor. The Marine Plant Biomass of the Pacific Northwest Coast. Oregon State Canadian Fisheries Research Board, Pacific Coast Station Progress Report 99:3-5. University Press, Corvallis, Oregon. 4. Carey, A. G. 1965. Preliminary Studies on Animal-Sediment Interrelationships off the 25. Reilly, P. N. 1983. Dynamics of Dungeness Crab, Cancer magister, Larvae off Central Central Oregon Coast. Ocean Science and Ocean Engineering 1:100-110. and Northern California. In P. W. Wild and R. N. Tasto, editors. Life History, Environ- 5. Carey, A. G. 1981. A Comparison of Benthic Infaunal Abundance on Two Abyssal ment, and Mariculture Studies of the Dungeness Crab, Cancer magister, with Empha- Plains in the Northeast Pacific Ocean. Deep-sea Research 28A:467-479. sis on the Central California Fishery Resource. California Fish and Game Fish Bulletin 6. Carney, R. S., and A. G. Carey. 1976. Distribution Pattern of Holothurians on the 172:57-84. Northeastern Pacific (Oregon, U.S.A.) Continental Slope, and Abyssal Plain. Thalassia 26. Robinson, J. G. 1971. The Distribution and Abundance of Pink Shrimp (Pandalus Jugoslavica 12:67-74. jordani) off Oregon. Fish Commission of Oregon Investigational Report No. 8. 7. Carney, R. S., and A. G. Carey. 1982. Distribution and Diversity of Holothurians 27. Saelens, M. R. 1983. 1982 Oregon Shrimp Fishery. Oregon Department of Fish & (Echinodermata) on Cascadia Basin and Tufts Abyssal Plain. Deep-sea Research Wildlife Information Report 85-5. 29A@597-607. 28. Snow, D. 1985. Personal communication. Oregon Department of Fish and Wildlife, 8. Cushing, D. H., and J. J. Walsh, editors. 1976. The Ecology of the Seas. W. D. Saunders Marine Region, Newport, Oregon. Co., Philadelphia, Pennsylvania. 29. Stander, J. M., and R. L. Holton. 1978. Oregon and Offshore Oil. Sea Grant Publication 9. Dickinson, J. J., and A. G. Carey. 1978. Distribution of Gammarid Amphipoda ORESU-T-78-004, Oregon State University, Corvallis, Oregon. (Crustacea) on Cascadia Abyssal Plain (Oregon). Deep-sea Research 25:97-106. 30. Starr, R. M. and J. E. McCrae. 1983. Weathervane Scallop (Patinopecten caurinus) 10. Gotshall, D. W. 1977. Stomach Contents of Northern Dungeness Crab, Cancer Investigations in Oregon, 1981-1983. Oregon Department of Fish and Wildlife, Informa- magister, in Northern California. California Fish Game 63:43-51. tion Report No. 83-10. 11. Grassle, J. F. 1982. The Biology of Hydrothermal Vents: A Short Summary of Recent 31. Waldron, K. D. 1958. The Fishery and Biology of the Dungeness Crab (Cancer magister Findings. Marine Technology Society Journal 16:33-38. Dana) in Oregon Waters. Fish Commission of Oregon, Contr. No. 24. 12. Griggs, G. B., A. G. Carey, and L. D. Kulm. 1969. Deep-sea Sedimentation and Sediment-fauna Interaction in Cascadia Channel and on Cascadia Abyssal Plain. Deep- sea Research 16:157-170. 13. Jumars, P. A. 1976. Deep-sea Species Diversity: Does it Have a Characteristic Scale? Journal of Marine Research 34:217-246. 14. *Kozloff, E. N. 1983. Seashore Life of the Northern Pacific Coast. University of Washington Press, Seattle, Washington. 15. Laugh, P. G. 1976. Larval Dynamics of the Dungeness Crab, Cancer magister, off the Central Oregon Coast, 1970-71. Fishery Bulletin 74:353-375. 16. Lukas, G.. and M. J. Hosie. 1973. Investigations of the Abundance and Benthic Distribution of Pink Shrimp, Pandalus jordani, Off the Oregon Coast. Final Report, Oregon Fish Commission NMFS project 1-3-R-5. 17. *Oceanographic Institute of Washington, 1977. A Summary of Knowledge of the Oregon and Washington Coastal Zone and Offshore Areas Volume I. Seattle, Wash- ington. 18. Pacific Fishery Management Council. 1979. Draft Fishery Management Plan for the Dungeness Crab Fishery off Washington, Oregon, and California: Pacific Fishery Management Council, Portland, Oregon. 19. Pearcy, W. G. 1970. Vertical Migration of the Ocean Shrimp, Pandalus jordani: A Feeding and Dispersal Mechanism. California Fish and Game 56:125-129. 20. Pearcy, W. G., D. L. Stein, and R. S. Carney. 1982. The Deep-sea Benthic Fish Fauna of the Northeastern Pacific Ocean on Cascadia and Tufts Abyssal Plains and Adjoining Continental Slopes. Biological Oceanography 1:375-428. no (D CHAPTER SEV EN m A ED ED /A [D LrALI @ [M[00 6%H[D) M&MM&LO Residents and Visitors I El @ UNI\XJ E [M Marine Birds Commonly Seen off the Open Oregon Coast-Their Preferred Habitat, Seasonal Occurrence, and Abundance. (Modified from Eltzroth and Ramsey, 1979) Family Gaviidae Family Phalaropodidae Family Anatidae Common Loon PR Cs C Red Phalarope MI Oc, Cs V Oldsquaw WRCsO Yellow-billed Loon VACsO Red-necked Phalarope MI Oc, Cs V Harlequin Duck PR Cs U Arctic Loon PCsc White-winged Scoter PR Cs V Red-throated Loon WRCsC Surf Scoter PR Cs V Family Laridae Black Scoter PR Cs U Glaucous Gull WRCsR Family Podicipedidae *Glaucous-winged Gull PR Cs V Western Grebe PR Cs C *Western Gull PR Cs V Family Haematopodidae Red-necked Grebe PR Cs U *Black Oystercatcher PR Sh U Horned Grebe PR Cs C Herring Gull WRCsLl Thayer's Gull WR Cs U California Gull PR Cs V Family Charadidae Family Diomedeidae Ring-billed Gull PRCsC Semilpalmated Plover MI Sh C Black-tooted Albatross PR Oc,Cs C Mew Gull WRCs V Snowy Plover PR Sh R Laysan Al bat ross WR Oc,Cs R Bonaparte's Gull MI Cs V Lesser Golden Plover MI Sh A Heermann's Gull SRCsC Surfbird WR Sh V Family Procellarflidae Black-legged Kittiwake ml Oc,Cs C Ruddy Turnstone WR Sh U Northern Fulmar M I Oc,Cs C Sabine's Gull Ml Oc,Cs U Black Turnstone WRShV INTRODUCTION Pink-footed Shearwater MI Oc,Cs U Common Tern M I Oc,Cs U Flesh-footed Shearwater M I Oc,Cs 0 Arctic Tern MI Cs U Family Scolopacidae ilently riding the wind of an incoming storm, roosting noisily on Bulleo's Shearwater M1 Oc,Cs U Caspian Tern SR Cs U Least Sandpiper PR Sh V rocky ledges, or wheeling and diving in the wake of a fishing Sooty Shearwater M I Oc,Cs V Whimbrel PR Sh C Short-tailed Shearwater M I Oc,Cs U Wandering Tattler MI Sh U boat, seabirds are important visual elements of the Oregon Family Alcidae Rock Sandpiper WR Sh U *Common Murre PR Cs V Dunlin WRShV coast. Likewise, the sight of sea lions basking in the sun, seals Family Hydrobatidae *Pigeon Guillemot SRCsG Western Sandpiper MlShV floating lazily on the waves, or whale-spouting above distant wavetops *Fork-tailed Storm-Petrel PR Oc,Cs C Marbled Murrelet PR Cs U Marbled Godwit MI Sh C adds to the richness of the coastal panorama. *Leach's Storm-Petrel PR Oc,Cs U Ancient Murrelet WR Cs U Sanderling WRShV *Cassin's Auklet PR Oc,Cs C But beyond their aesthetic appeal to coastal visitors, both marine birds Family Pelecanidae Parakeet Auklet VA Oc,Cs 0 Family Stercorarildae and mammals are important components of the marine ecosystem. And Brown Pelican** SRCsC Rhinoceros Auklet PR Cs C Pomenne Jaeger MI Oc,Cs U Horned Puffin VA Oc,Cs 0 Parasitic Jaeger MI Oc,Cs U even though they spend much time at sea, both birds and mammals are Family Phalacrocoracidae *Tufted Puffin PR Oc,Cs U Long-tailed Jaeger MI Oc,Cs U highly dependent upon the habitat provided along Oregon's coastline for *Double-crested Cormorant PRCsV South Polar Skua M I Oc,Cs R breeding and rearing young or for resting and feeding during migration. *Brandt's Cormorant PR Cs V The location and health of these habitat areas are vital to the breeding *Pelagic Cormorant PR Cs V success and survival of various bird or mammal species. This chapter of the Oceanbook discusses in detail marine birds which *Breeds along open coast and on sea islands. Abundance (during peak period): Preferred Habitat on Open Coast (some species also live in bays, breed along the coast and marine mammals which either haul out (leave Endangered species V - very common (50 or more birds/day/observer) estuaries, and further inland): the water) along the coast or are commonly found in the waters off C - common (10-49 birds/day/observer) Sh - Shore (sandy beach and rocky intertidal) Oregon. In addition, marine bird and mammal species that only visit the Seasonal Occurance: U - uncommon (0-9 birds/day/observer) Cs - Continental Shelf PR - Permanent resident R - rare (5 or less birds/year/observer) Oc - Oceanic (beyond Shelf) coast are described. SR - Summer resident E - extremely rare (5 or less birds/year/all observers) WR - Winter resident 0 - occasional (not seen every year but occasionally present) MI - Migrant MARINE BIRDS VA - Vagrant Marine Bird Characteristics arine birds differ from other terrestrial birds in a variety of ways. First, they spend much of their lives in association with Other important differences are the age of first reproduction and clutch scooping up prey with the pouchlike extension of its lower mandible. the sea. Some (for example, gulls, pelicans, and cormorants) size (the number of eggs in a single nest). Many seabird groups have Figure 65 summarizes the variety of feeding methods of marine birds remain close to shore throughout their lives; others (such as extended juvenile periods, becoming sexually mature after three to found off the Oregon coast. albatross, storm petrels and alcids) are at sea for extended periods and seven years. These birds typically lay small clutches of only one or two A webbed foot provides an advantage in the aquatic environment. return to land only to breed. Of the truly pelagic seabirds, several are eggs per year. Marine birds, therefore, maintain their numbers by Diving birds such as cormorants and murres are well endowed for nocturnal on the breeding grounds, entering or leaving their colonies producing relatively few young per year over a long lifetime. pursuing their underwater prey with short legs and large webbed areas only at night. Marine birds commonly seen off the Oregon coast are between their toes. However, because their legs are positioned farther listed in the accompanying Table. Seabirds are well adapted to exploiting the ocean's resources, having back on the body, diving birds are less adept onshore and sway from Probably the most striking difference between marine and terrestrial evolved a remarkable variety of specialized beaks, feet, and body side to side as they amble over land. The legs and feet of shorebirds, on birds is the longevity of marine birds. Upon reaching adulthood, many shapes for feeding and breeding. A rhinoceros auklet snaps up fish with the other hand, are better suited to life ashore. Some possess short legs marine birds live for years. Annual mortality rates commonly run below 20 a heavy, bony bill and holds them with its tongue while continuing to for dashing to and from the water's edge; others can wade atop long, percent, whereas those for terrestrial birds can be 40 to 70 percent (112). catch more fish. A black oystercatcher can pry limpets off rocks with its spindly legs while searching for small fish in shallow bays. Some banded individuals have lived for 20 to 30 years. long, stout bill. A brown pelican plunges into the surface waters, 7 T Birds in the Marine Ecosystem y1s, irds are an important component of marine communities in that a significant proportion of the energy passing through the .5RE4_t:'D11YCT 5E_A5h2D,5 OF TIE Oregon coastal ecosystem is channeled into their survival. 0P--Z__C701Y COAST Small pelagic fish are the principal food of many marine birds. Northern anchovy, Pacific herring, rockfish, smelt, sculpin, and cod are- all eaten by seabirds in great numbers. POPUL@ATIOIVS AAIZ:) P&2CFW7_-5 Computer simulation models have been used to estimate how many of these fish are consumed each year by four species of Oregon seabirds: sooty shearwaters, Leach's storm petrel, Brandt's cormorant, and the ... ........... AWN11, common murre (18). Results have shown that about 125 million pounds of pelagic fish may be eaten annually by these four species (18). This V//IICT =11111111/1 catch approximates that landed annually by commercial fishermen in Oregon and is estimated to be nearly 22 per cent of the annual 00 q,flVf@4Z_ production of small pelagic fish. The northern anchovy is particularly APW-LL 154LCCMb, 1982,, ATLA 5 CF 71F, 1677 important as a food source, providing approximately one-half of all prey consumed. Figure 65. Feeding Stategies of Open Coast Marine Shearwaters play an important role in the flow of energy from fish to Birds. birds, Estimates indicate that for a few brief months during their fall ........... .. ....... ........ . ... migration off Oregon, shearwaters consume seven times as much food Marine birds use a variety of feeding methods to capture the many as either common murres, Brandt's cormorants, or storm petrels (18). food resources of the ocean. Each feeding method, or combination .......... .......... However, when computed on an annual basis, the total energy demand . . ......... . of methods, allows that species to exploit a particular niche in the .N food supply and thus improve its chances of survival and reproduc- of common murres exceeds that of the other three species. I LF_A6H'5 -5-MP&I Q-7 .P tion. 7.) ...... mi 2'7 7,2-Z 7 M 3 Y.) ........... Oregon Marine Bird Populations ... .... W-2 X he total number of breeding seabirds in Oregon is estimated to be 450,000 (15). Year-to-year fluctuations in the number of A streamlined body like that of the cormorant is most useful in propelling breeding birds can often be attributed to oceanographic condi- the bird efficiently through the water. The wings of the alcids, large in tions. The intensity and duration of upwelling, for example, may proportion to a small body size, are used like paddles to maneuver the influence both the number of birds that breed and the survival of bird quickly and powerfully in search of prey. offspring (12). Most birds have a gland situated at the base of the tail which secretes Most seabirds are colonial nesters; consequently, colony sites are PI@ZACI-10 CneMM4NT' oil. Continual preening spreads the oil over the birds' feathers and critical areas for marine birds. Large numbers of birds aggregate within L 6,321 makes them waterproof. Seabirds repeat this routine several times a these nesting areas, using the social stimulation of the colony to day. Some species are not so well endowed; cormorants need to leave synchronize hatching, to ward off predators, and to forage for food in After the water to spread their wings to dry after diving. waters close to the colony. Both human and natural disturbances around Seabirds are most abundant along the shore and over the continental seabird colonies can severely affect the survival and reproductive shelf where prey is plentiful. Prey is known to accumulate in frontal success of a species. Figure 67 shows the locations of known seabird Figure 66. Populations of Breeding Seabirds and regions, which are boundaries between oceanic water masses such as colonies along the Oregon coast. Proportion of the Total Seabird Population of Each the zone where cool, upwelled nearshore water meets warmer offshore Species in Oregon water, A rich supply of nutrients at the surface in these regions permits Oregon's seabird population is dominated by two species, the abundant plant growth, which in turn supports zooplankton and small common murre and Leach's storm petrel. All other species com- fish. Petrels, terns, and shearwaters occur on the warm side of the fronts bined, including the familiar Western gull, account for less than ten and murres and auklets on the cold side of the fronts (13). per cent of the total population. LIFE HISTORIES OF OREGON'S BREEDING SEABIRDS Thirteen species of seabird breed along the Oregon coast. Their life histories are breifly duscussed in this section (5,1,10,12). as illustrated in Figure 66, common murres and Leach's storm petrels account for approximately 94 per cent of Oregon's breeding seabirds while the other twelve species combined, including gulls, total only 6 per cent. CORMERANTS Family Phalactocoracidae Three species of cormorants live in Oregon year-round. All are blackish, with slender, hook-tipped bills, and the adults often have colorful face skin and gular pouch. The Brandt's cormorant (Phalactocorax pen- icillatus), the most common cormorant of the Oregon coast, has a blue throat pouch during the breeding season. It is also the largest of the species, up to 74 centimeters (approximately 30 inches). Double-crested cormorants (Phalacrocorax auritus) range to nearly 70 centimeters (27 inches) and have an orange-yellow throat pouch. They are the only species to regularly occur in freshwater habitats. Pelagic cormorants (phalactocorax pelagicus) are the smallest (56 centimeters or approx- imately 22 inches) of the three cormorant species. They have a white patch on each flank and a dull red throat pouch during the breeding season. Although they are the most widespread, they are the least gregarious of the three species. Range. The breeding seasons of the three species are staggered, a fact that reduces competition for food among the birds. Brandt's cormorants usually nest on flat tops of offshore islands and, less frequently, on inaccessible mainland bluffs and cliff ledges. Nests are generally made of seaweed, but uprooted plants may also be used, which can cause significant impact to local plant ecology. Clutch size is three to six eggs. Double-crested cormorants nest in a variety of habits from offshore rocks to abandoned timbers in estuaries and even inland locations. Nests, built primarily by males, are large twiggy masses, built up year after year. Nests typically contain three to five eggs, but as many as nine have been reported. Pelagic cormorants build nests on inaccesible cliff faces using sea- weed and other vegitation plastered together with guano. From three to seven eggs are laid in the nest. Feeding. Strong swimmers, cormorants pursue small fish such as herring and shrimp and are capable of swimming to depths of more than 20 to 50 meters. These birds lack water-repelant plumage, however, and must occasionally leave the water to dry. Figure 67. Colonies of Breeding Seabirds in Oregon Twelve species of seabirds breed along the Oregon coast, nesting on offshore islands and on the mainland where hte interference from humans and predators is minimized. STORM PETRELS Family Hydrobatidae Leach's storm petrels, Oceanodroma leucorhoa, are small (approx- imately 19 centimeters, or 7.5 inches) and black with a white rump patch. They are the most abundant member of this family in Oregon. Fork-tailed storm petrels, Oceaodroma furcata, are small (approximately 19 cen- timeters, or 7.5 inches) and grey, with a forked tail. Figure 68 Fork-tailed Storm Petrel (photo by Ron LeValley) Although present along the Oregon coast, these small birds are not frequently seen. They seek food far at sea and come ashore at night to nest in burrows away from gulls and other predators. Range. Leach's storm petrels are found off Oregon only during the summer breeding season; they migrate to the tropics during winter. Fork-tailed storm petrels remain off Oregon year-round. Breeding. The breeding range of both species overlaps across the North Pacific Ocean to norhtern California. Both species of storm petrels mate, brood, and feed their young at night to avoid predation by gulls that are often nesting in the immediate atea. Breeding occurs during the spring, and only a single egg is produced. Leach's storm petrels prefer rocky crevices on offshore rocks for their nest site. Fork-tailed storm petrels nest underground in burrows. Nocturnal activity by storm petrels makes them difficult to detect and study. Feeding. Storm petrels range well offshore from their breeding grounds to forage. Leach's storm petrels prefer offshore waters and in winter off California, for example, are uncommon within 30 kilometers of shore. They feed on zooplankton, small fish, and crustaceans. Fork-tailed storm petrels also search the open waters over the continental shelf for food but tend to stay nearer shore than the Leach's storm petrel. They feed on shrimp, zooplankton such as euphauslids, and small fish. MARINE BIRDS AND MAMMALS 73 MURRES, GUILLEMOTS, MURRELETS, AUKLETS, AND Breeding. Common murre colonies are often extremely large and dense The guillemots'diet consists of small fishes. Equipped with a narrow bill, PUFFINS Family Alcidae with tens or hundreds of thousands of individuals packed shoulder-to- like the murre, they can carry only a single fish to their young. Alcids, the northern counterpart of the penguin family, are small, shoulder during the breeding season. Nest sites are usually flat rock Cassin's auklets feed in shallow water on small fish and planktonic torpedo-shaped seabirds with short, broad wings well suited as much for surfaces on island tops or ledges. Murres lay a single egg, whose pear invertebrates far from the nest site. Adults store food in a pouch beneath underwater swimming as for flying. Six species of alcids breed on small shape keeps it from rolling too far away. Both parents feed the chick until the tongue and regurgitate it for the young. islands or on rocky outcrops of the mainland along the Oregon coast. it is ready to leap from the colony and swim away with the male parent. Rhinoceros auklet tongues are modified with teethlike structures so that The Common murre, Uria aalge, is 36 centimeters (14 inches) long, with Pigeon guillemots nest in loosely scattered pairs on offshore islands and more than one prey item can be held in its mouth at a time. These auklets a slender, pointed bill. In breeding plumage, its head, neck, back, and rocks but may also occur on precipitous headlands and structures such feed on small fish and crustaceans. wings are dark with white underparts. as pier pilings. The two-egg clutch is laid in rock crevices directly on the The tufted puffin's tongue is modified like that of the rhinoceros auklet, The pigeon guillemot, Cepphus columba, is a small bird, 27 centimeters ground. They are one of the few alcids that can raise two chicks. enabling it to transport fish on both sides of its beak. In addition to small (10.5 inches) long. Typical coloration is black with large white shoulder fishes, tufted puffins consume crustaceans, cephalopods, sea urchins, patches and red feet. and molluscs. Figure 69. Tufted Puffins (photo by Ron LeValley) Figure 70. Common Murre Although best adapted to "underwater flying", the puffin's wings (photo by Tish Parmenter) none-the-less function well enough in air to allow the bird to nest on From the tip of its sharp, tapered beak to its webbed feet set well rocky cliffs high above the water. rear of its streamlined body, the common murre is a superb diver and swimmer. The Cassin's auklet, Ptychoramphus aleuticus, is dark with a white belly. Cassin's auklets nest on offshore islands, laying a single egg in burrows It is a small seabird, 18 centimeters (7 inches) long. excavated with sharp toenails. Because their small size makes them Figure 71. Pigeon Guillemots The rhinoceros auklet, Cerorhinca monocerata, has a keratinous "horn" likely prey for gulls, they are nocturnal breeders. (photo by Ron LeValley) at the base of the upper bill, from which the species derives its name, but Rhinoceros auklets lay a single egg at the end of a burrow up to six Like common murres, tufted puffins and other members of the this and the narrow white plumes behind the eye are present only during family Alcidae, the pigeon guillemot is we// adapted to diving and the breeding season. It is 29 centimeters (11.5 inches) long. meters (19.8 feet) long, on grassy slopes and forested areas mostly on pursuing small fish. One of this group of six has indeedjust caught offshore islands. Typically, the nest site is visited only at night. lunch. The tufted puffin, Lunda cirrhata, is one of the most unusual-looking Tufted puffins nest in deep burrows, which they excavate with their seabirds, black with a triangular-shaped, bright orange beak and white beaks and sharp claws, and lay a single egg. Nesting sites are generally eyebrow plumes, both of which are lost after the breeding season. on offshore islands. Activity at the nest can occur during the day since Differences in the beaks of alcids and in their feeding habits tend to their large size keeps them from being harassed by gulls. During the separate individual species and reduce competition for food. Some feed breeding season, they are very conspicuous around nesting colonies, in shallow nearshore water, while others feed much further offshore in but during the winter, disperse over the open ocean and are rarely seen deeper water. over continental shelf waters. Range. These alcids share a breeding range that extends from central Feeding. Common murres prey on small fish which are brought back to Alaska to central California. For a few, the breeding range spans the the chick one at a time. Murres are deep divers, up to 200 meters, and north Pacific basin: north to the Kurile Islands for the pigeon guillemot can remain submerged for up to four minutes (16). Murres have been and to northern Japan for the tufted puffin. The southern breeding range observed feeding on salmon smolts off the mouths of Oregon's estuaries of the Cassin's auklet extends to central Baja California. where salmon hatcheries release large numbers of fish. 'AOL L 74 MUOHE 00[203. MD BLACK OYSTERCATCHER Family Haematopodidae GULLS Family Laridae Breeding. The nests of these two species are usually placed on offshore The black oystercatcher, Haematopus bachmani, is a stout, black Gulls are highly visible members of the nearshor .e bird community, islands and rocks, but small colonies can also be found at mainland sites shorebird, 38 centimeters (15 inches) long, inhabiting the interticlal zone frequently forming large groups on beaches and jetties. Although many that are free from predators and human disturbance. The average clutch along rocky shores. It possesses a long, flat, orange-red bill and pale species can be found on the coast, few are year-round residents. Only is three eggs. Like most seabirds, gulls remain faithful to their nest site legs. the glaucous-winged gull, Larus glaucescens, and western gull, Larus and their mate throughout their lifetime. Range. Black oystercatchers are found from central Baja north through occidentalis, breed on the open Oregon coast. Both are large birds, 54 to Feeding. Gulls are opportunistic feeders, including many different items the Aleutian Islands. 56 centimeters (21 to 22 inches) long. The western gull has a very dark in their diet: small fish, the young of other birds, squid, euphausiids, back and wings, a light underside, and pink feet, while the glaucous- cannery waste, and garbage. Like jaegers, they sometimes steal the Breeding. During the breeding season, oystercatchers are usually winged gull has a pale gray back, a gray wing pattern on the wing tips, food of other birds. Gulls are one of the few seabirds that may have paired, but often single. They lay three eggs in nests of small pebbles and pink feet. Because the distinguishing colors of the feet, bill, and benefited by human activity, increasing in number possibly because of and shell fragments built just above the splash zone in rocky areas along wing of the adult are usually not well defined until the third year, juvenile additional food resources made available by the widespread use of open the entire Oregon coast. Young oystercatchers are precocious, leaving gulls are extremely difficult to identify. landfills. the nest within a few hours of hatching. Range. Western gulls reside from Baja California to northwest Wash- Feeding. The heavy bill is used to pry mussels, limpets, and chitons from ington. The glaucous-winged gull breeds farther north, from the Bering the interticlal zone. Sea and Gulf of Alaska to the northern coast of Oregon. MAM '40 _0 N 'w k! q,- % 0 .... ... .... ... . V 121 14; ...... ..... . VMMHM@@!,-, : tER ... ... .. ...... IMP .. ..... .... . . . . . . . . . . ........ . ............. . . . . ....... . Figure 72. Black Oystercatcher Figure 73. Western Gull in Flight. (photo by P. LaTourrette, courtesy of Richardson Bay (photo by Ron LeValley) Audubon Center) A large wing span and a nearly constant breeze allow the western A well-balanced body and stout beak allow the black oystercatbher gull to cruise the wind in search of food while conserving body to pry food from the rocks along the shore at low tide. energy. This method carries the gull effortlessly over a broad area and is appropriate to the gull's scavenger feeding habits. Although the western gull is the bird most often associated with the coast, it is far from the most numerous. Gulls comprise only one and one- half per cent of a// marine birds on the Oregon coast. Common Nonbreeding Seabirds of the Oregon Coast DUCKS Family Anatidae Ten families of seabirds found along the Oregon coast are common Sea ducks dive for fish, crustaceans, and molluscs, propelled by visitors but do not breed here. webbed feet larger than freshwater ducks. Their legs are positioned well LOONS Family Gaviidae JL to the rear of their bodies, increasing the efficiency of their kick. Loons are diving birds with a clucklike body and a long, heavy, pointed Scoters are the dominant sea duck of Oregon. Three species are very bill. Unlike most birds, they have solid bones which allow them to common: the white-winged scoter, Melanitta fusca, the surf scoter, submerge easily. Some dive as deep as 60 meters in pursuit of small fish Melanitta perspicillata, and the black scoter, Melanitta nigra. Although and shrimp. Loons eat amphipods, crabs, and molluscs. The common present year-round in Oregon, most individuals fly north in summer to loon, Gavia immer, is found throughout the year on the Oregon coast, breed in Canada and Alaska. They are commonly observed resting on whereas other species of this family are winter residents. open water. Oldsquaw ducks, Clangula hyemalis, and harlequin ducks, Histrionicus GREBES Family Podicipedidae histrionicus, are also winter inhabitants of the Oregon coast. Grebes are also diving birds. While swimming at the surface, grebes frequently dip their heads below the water to look for food. Shrimp and PLOVERS Family Charadriidae small fish are important to their diet. Several species of grebes live in Members of the Charadriidae family of shorebirds have compact bodies Oregon estuaries and bays, but the western grebe, Aechmophorus with thick necks and short bills. Plovers stalk their prey, stopping occidentalis, is the most abundant species on the open coast. Western All occasionally to probe beach sands or kelp. Their food consists of grebes breed on inland lakes: common interticlal animals: crustaceans, worms, and molluscs. ALBATROSS Family Diomedeidae Sernipalmated plovers, Charadrius semipalmatus, are most abundant on J sandy beaches during the summer as they migrate from their winter Albatross are among the largest of all seabirds. The black-footed feeding grounds (southern California to South America) to their breeding albatross, Diomedea nigripes, has a wingspan of 205 centimeters (80 inches), enabling it to glide long distances over the surface of the water grounds (northern Canada and Alaska). Snowy plovers, Charadrius alexandrinus, breed on sandy beaches in Oregon and are potentially without flapping. The black-footed albatross can be found off Oregon in greatest numbers through the summer months. Breeding occurs on the '4 threatened by human disturbance (15). northwestern Hawaiian Islands. Males and females generally pair for life. The black-footed albatross feeds on squid, pelagic crab, and surface SANDPIPERS, TURNSTONES, AND SURFBIRDS fish. Family Scolopacidae SHEARWATERS AND FULMARS Family Procellarfidae Most of the shorebirds belong to the Scolopacidae family. The most abundant species, the surfbird, Aphriza virgata, and the black turnstone, Shearwaters and fulmars, like albatross, travel long distances over the Arenaria melancephala, spend most of the year on rocky shorelines and open ocean. They are seen off Oregon while in transit between southern then migrate to Alaska for the summer breeding season. The wandering hemisphere breeding and subarctic feeding grounds. The sooty shear- tattler, Heteroscelus incanus, and rock sandpiper, Calidris ptilocnemis, water, Puffinus griseus, abundant along the Oregon coast between are also found along rocky shores. The other species frequent sandy spring and fall, breeds in New Zealand and off Cape Horn. beaches. Western sandpipers, Calidris mauri, and sand sanderlings, Northern fulmars, Fulmarus glacialis, occasionally seen off Oregon Calidris alba, are often seen feeding on the edge of the surf zone, where between fall and spring, breed on islands in the Gulf of Alaska and the they move up and down the beach with the advance and retreat of Bering Sea. No member of this family breeds in Oregon. Shearwaters breaking waves. Sandpipers eat amphipods and marine worms. and fulmars feed on squid, sand lances, anchovies, and euphausiids. BROWN PELICAN Family Pelecanidae PHALAROPES Family Phalaropodidae Brown pelicans, Pelecanus occidentalis, are summer residents of Phalaropes are relatively small seabirds with slender, pointed bills. Two Oregon's coastal zone where individuals are commonly found in bays species, the red phalarope, Phalaropus fulicarias, and the red-necked and nearshore waters. Breeding occurs on islands off southern California Figure 74. The Brown Pelican phalarope, Phalaropus lobatus, pass along the Oregon coast in the and Mexico. Pelicans plunge into the water from heights of 10 meters (33 spring and fall. Both species breed in Alaska. Most red-necked pha- feet) or less when diving for shallow-dwelling food. Small fish such as (photo by Dean Jue, courtesy Richardson Bay Audubon laropes winter south of the equator; red phalaropes winter south of northern anchovies are important prey. Center) California. The red-necked phalarope uses its feet to stir the water The familiar large pouch under the pelican's lower mandible is surface while feeding. Presumably the small fish and euphausiids fed The brown pelican was placed on the list of endangered species in 1970 folded neatly out of the way when not in use. Scarce along the upon by this bird are attracted or concentrated by the stirring activity. following a rapid decline in its abundance. Studies of nesting popula- Oregon coast over the past few decades, the brown pelican is now tions in California revealed that this decline was caused by pesticides seen more frequently in summer months as the breeding population present in the pelican's diet. As the levels of these chemicals increased in California increases. JAEGERS Family Stercorarfidae within the bird, its eggshells thinned and hatching success decreased. Jaegers are uncommon along the Oregon coast. The three species Because the use of these pesticides is now banned or restricted, the which have been observed breed on arctic tundra in the summer and brown pelican, is making a strong recovery. migrate southward to spend winters south of California. Jaegers obtain food by harassing gulls and terns until the gull has either dropped or disgorged its meal. They also prey on fish and scavenge on floating refuse. X&ROMIR DORM MHD X&MIXIMMO MARINE MAMMALS The cold waters of the Pacific Ocean off Oregon are home to a variety of marine mammals. Like their terrestrial counterparts, these warm-blooded, air-breathing animals give birth to young libe and nurse them until they are able to fend for themselves. Whales, dolphons, and porpoises, together known as cetaceans, are among the most ancient marine animals. Approximately 65 million years ago, their terrestrial ancesters ventured into the sea to take their place alongside the fishes and reptiles as the adapted to a strictly oceanic existence. A second group of mammals, known as pinnipeds and including seals and sea lions, embarked on an oceanic way of life long after the cetaceans made the sea their home. Cetaceans Cetaceans are easily distinguished by their horizontal tail flukes, the absence of hind limbs, and nostrils modified as blowholes on top of the head. these holes close when the animal submerges so that water is not inhaled. The spout seen when a whale exhales is the water vapor from the lungs condensing as it enters the air. Cetaceans have a thick layer of fat beneath the skin which assists in regulating the body's temperature. Their sense of hearing is well developed. many rely on echolocation (reflected soundwaves) for orientation and finding food. Because most cetaceans are gregarious, some establishing complex social organizations, sound is also important in communication between individuals. Cetaceans belong to two major groups: the mysticetes, filter-feeding whales, and the odontocetes, toothed whales. Mysticetes lack teeth and have instead sheets of comblike plates, called baleen, hanging from the roof of their mouth. The baleen sieves organisms low on the trophic ladder of the sea: copepods, euphausiids, amphipods, and small fish. Most baleen whales migrate from temperate and tropical breeding grounds to northern feeding grounds where production is most abundant during the spring and summer. The mysticetes are made up of three fmilies, but only two are common off the Oregon coast. The first and most frequently observed is the gray whale, the only libing representative of its family, Eschrichtiidae. A second family, Balaenopteridae, or rorquals, including the minke whale, the humpback whale, and the blue whale, are seen ingrequently in waters well offshore (9). Rorquals, also known as "gulpers", have long throat and chest pleats that expand like an accordian during feeding. The toothed odontocetes, well represented off the Oregon coast, include the commonly observed harbor porpoise and the Pacific white-sided dolphin. The differences between porpoises and dolphons are few. Porpoises have short, round snouts and spade-shaped teeth whereas dolphons have beaklike snouts and round teeth. Other odontocetes, sperm whales and Dall's porpoises, are seen far offshore, but sightings are rare. Killer whales are usually seen several times a year, both near the shore and in coastal rivers (9). Figure 75. Marine Mammals of the Oregon Coast- Their Area of Highest Abundance and Seasonal Occurrence. This chart showsmarine mamals organized by major groups as noted in the test. Species whose numbers have been severely depleted are considered threatened or endangered under the Endangered Species Act of 1973. Secen such species are listed for Oregon and are thus eligible for special protection under U.S. law. The drawings show approximately correct size proportions among cetaceans and between pinnipeds. Not all members are shown. Much research is needed to resolve questions about the presence of some marine mammals. Pinnipeds Unlike cetaceans, pinnipeds have preserved the ability to move about on land. In the water the body is streamlined and torpedo shaped and all four limbs are modified into paddle-shaped flippers for mobility. The four major groups of pinnipeds are the true seals (harbor seals and elephant seals), sea lions (sea lions and fur seals), walruses, and sea otters. Seals, sea lions, and fur seals are found along the Oregon coast while walruses are confined to the Arctic. The sea otter was abundant in Oregon befor its exploitation by hunters. Seals and sea lions can be distinguished by their different behacior and physical characteristics (see Figure 76). Seals are smaller than sea lions, with flippers which cannot be rotated and hind legs which cannot reverse for locomotion on land. Thus, they can only wiggle along on their bellies when out of the water. Harbor seals, perhaps the best-known species of this group, are often seen in typical repose, bobbing lazily at the surface. While on land, seals are notably silent, except for an occasional wheeze. Sea lions are large and have external ear flaps. Their front flippers are larger than the back ones, and, unlike those on seals, the hind flippers can rotate forward, allowing the animals greater movement on land. While out of the water, sea lions are extremely vocal. Although pinnipeds spend much of their life at sea feeding on fish and invertebrates, they must return to land to breed and bear young. harbor seals copulate in the water, but they, too, come ashore to give birth. Breeding grounds are known as rookeries. The adult male sea lion and the elephant seal-a true seal, in that it does not have external ears- establish a harem of many females, which they defend vigorously against intruders. At times other than the breeding season, pinnipeds often return to protected shore areas and offshore rocks, known as haulout sites, to rest. Pinnipeds generally abound off the Oregon coast. Depending on the time of year, the populations of California sea lions, northern sea lions, and harbor seals can each reach approximately 4,000 animals (9). The California sea lion is a migrant, but a small population of northern sea lions (alson known as Steller's sea lions) breeds on the southern coast. Harbor seals are nonmigratory, though their home tange is fairly large. Northern sea lions are found in the near to offshore region. Harbor seals and California sea lions are found in coastal rivers and the nearshore ocean, though California sea lions go farther offshore (9). A few hundred northern fur seals and northern elephant seals are seen on a seasonal basis. Fur seals are difficult to keep track of since they stay well offshore. Sightings of the animals usually occur during the winter migration from their Bering Sea rookeries, and most are females. Young elephan seals commonly appear at a few haul-out sites in the summer (9). MARINE BIRDS AND MAMMALS 77 COMMON MARINE MAMMALS OF THE OREGON NORTHERN (STELLER'S) SEA LION Eumetopias jubatus COAST Northern sea lions range from the Channel Islands off southern California 'V, "ZIA-, TYPICAL PROFJLL IN THE WATER his section includes descriptions of marine mammals commonly north along the coast to the Bering Sea and south again along the western Pacific to the Sea of Okhotsk. observed off the Oregon coast such as harbor porpoises, Pacific white-sided dolphins, gray whales, northern and California sea It is a nearshore species although sightings have been made 160 NAIL@ CT lions, and harbor seals. Also noted are other species of marine kilometers offshore. Figure 78 shows haul-out areas on the Oregon mammals less frequently seen in the waters off the coast-humpback coast. Approximately 3,000 of the world population of 300,000 indi- 541S A Z@/Ovvs whales, blue whales, minke whales, sperm whales, killer whales, Dall's viduals (6) breed in Oregon on rock outcrops and rocky or coarse sand porpoises, northern elephant seals, and northern fur seals. These beaches. At the end of the mating season in July, some males migrate I-IT'ICAL PROFILL IN THLWATEJ@ species descriptions have been compiled primarily from references 8 northward from these breeding locations to British Columbia and Alaska. and 1. Most Oregon females and pups remain off the coast throughout the HARBOR PORPOISE Phocoena phocoena winter. Harbor porpoises are found throughout the cooler regions of the North This species can be distinguished by a tawny pelt and the thick mane Pacific. On the west coast of North America they range from Alaska which the male develops around its oversized neck. Size varies greatly between the sexes; males may grow to four meters (13 feet) and weigh /VA/Z'@ P,11 I 7=1 NIIYA@@_ F V/) I<,- south to San Diego, California. 900 kilograms (2,000 pounds), whereas females grow to approximately Arit- VAROWt_wi. n1,4 The harbor porpoise is the smallest cetacean in the eastern North Pacific half that length and weight. (1.3 meters long) and perhaps the most abundant. The breeding season Among the many types of food found in the stomachs of northern sea is in late summer with a 9- to 10-month gestation period. Harbor lions are squid, Pacific whiting, herring, and rockfish. Figure 76. Distinguishing Characteristics of Seals porpoises are most common nearshore and less frequent in bays and and Sea Lions estuaries. CALIFORNIA SEA LION Zalophus californianus They feed on bottom fish, cod, herring, squid, clams, and crustaceans. California sea lions have a more southerly distribution compared to that of the northern sea lion. They range from British Columbia to Mexico with PACIFIC WHITE-SIDED DOLPHIN all breeding occurring south of Oregon. 77 Lagenorhynchus obliquidens ft When mating is concluded in mid-July, some males migrate northward to Pacific white-sided dolphins are among the most abundant of all eastern overwinter as far as British Columbia. Populations in Oregon reach a Pacific cetaceans. They range primarily along the continental shelf from peak of 3,500 individuals during the early fall. Males move southward Baja California to Alaska in the northeastern Pacific and from Japan to again in the spring to breed. Figure 78 identifies sites along the Oregon the Kuril Islands in the northwestern Pacific. Individuals are found coast where California sea lions are known to haul out. Although the throughout the year off California and Washington. Abundance in length of both sexes is quite similar-males are 2 meters (seven feet) California peaks in the fall and reaches a minimum in the spring. and females 1.8 meters (six feet)-the males weigh more than the Seasonal changes in distribution have been observed, with these females, 270 kilograms (594 pounds) to 90 kilograms (198 pounds). % dolphins being found closer to shore in the winter than in the summer. Food for this sea lion includes hake, herring, rockfish, and sculpins. White-sided dolphins form large pods numbering more than a thousand Observers have seen California sea lions eating large salmonids and individuals and are often seen riding the bow wake of a vessel at sea. lampreys around the mouth of rivers. Mating takes place from late spring through autumn, with birth occurring after a 10-month gestation period. White-sided dolphins feed on squid, herring, sardines, anchovy, saury, and jack mackerel. Figure 77. California Sea Lions at Simpson Reef, Near Coos Bay (photo by Bruce Mate, OSU Marine Science Center) Nearly 80 sea lions have hauled out of the water on this rock at Simpson Reef, at Cape Arago. Although located well offshore away from human interference, the reef is visible from a lookoutjust north of the Cape Arago State Park entrance. Ideally situated for easy access to and from the water, the reef is composed of eroded, gently sloping sedimentary rocks just above sea level. At low tide, sandy beaches surrounding these rocks facilitate exit from the water. Other haul-out rocks just above the surf may be seen at the foot of the cliff within the park. Farther north, near Florence, sea lions have colonized caves eroded into the base of steep basalt , @-Ne-7_,26 cliffs. These caves are a popular tourist stop. cy no BiA COLUMBIA COLUM81 COLUM At, Z Figure 79. Harbor Seal Basking on Rocks HARBOR SEAL Phoca vitulina Harbor seals are year-round residents of the Oregon coast. They are not 0 0 0 migratory, although seasonal movements into bays and estuaries are common. Around 300,000 harbor seals are thought to live in the eastern Pacific. Estimated abundance off the Oregon coast is 5,200 (3). Over 1,500 are found in the Columbia River; 800 in the Umpqua River; 1,200 in the Coos bay and Cape Arago region; 600 around Tillamook bay; 300 around the Rogue River; and more than 200 in Netarts Bay, 100 in Siletz Bay, 300 in Alsea Bay, and 200 near Bandon. These animals use sand bars, mud flats, small rocks, islands, and reefs as hauling out areas. Harbor seals are shy and will abandon their haul-out (0 Lu uj Lu IT area if approached. They are more gregarious during the late spring CIO when pups are born and during the fall. Sexes are approximately the same size, ranging in length from 1.2 to 1.8 meters (four to six feet) and from 45 to 105 kilograms (99 to 231 pounds). Harbor seals eat bottom fish, rockfish, herring, and some salmon. Am 0 0 0 Ca Co. C" &z. o Glanc cc BlMo -- - ------- "V IW I-1AR.50R, 5EA1_5 CAL@1fMW 6EA LIONS -q--@ "OVS Figure 78. Coastal Haul-Out Sites for Harbor Seals, FRC111;NATE' lqleYl California Sea Lions, and Northern Sea Lions. _;rCo_@,U.BIA rO,,m817A -Y HARME Mon. Mo 700 NORTHERN FUR SEAL Callorhinus ursinus DALL'S PORPOISE Phocoenoides daffl SPERM WHALES Physeter catadon Northern fur seals breed on islands in the Bering Sea and on San Miguel The Dall's porpoise is the most common porpoise in southeast Alaska Sperm whales are the largest of the odontocetes. They spend the Island in Baja California during the summer. Those which breed in the and British Columbia. It is a year-round resident of both California and summer in the Bering Sea and migrate south for the winter. They usually Bering Sea migrate as far south as California during the winter. British Columbia, and individuals have been found off the Oregon coast. travel well offshore Oregon between March and September; however, All individuals spend at least eight months on the open sea and are The Dall's porpoise is larger and more conspicuous than the harbor forty-one sperm whales were stranded on the beach at Florence, pelagic while in Oregon. They are usually seen from 16 to 160 kilometers porpoise. Unlike many other porpoises, Dall's porpoises do not form Oregon, in July 1979 (see Figure 81). (10 to 100 miles) from shore with most sightings during the winter and large schools; sightings are usually made of fewer than 24 individuals The sperm whale has a huge head'with a large frontal area, and only its fewest in the summer. traveling together. narrow lower jaw has teeth. It feeds on bottom and in midwater on squid. Fur seals feed from evening until early morning and then rest during the Dall's porpoises eat squid, Pacific whiting, herring, jack mackerel, saury, This whale is perhaps best known for ambergris, a material produced in day. They may dive to 190 meters while feeding. The diet off Oregon and some cleepwater benthic fish. its digestive tract, which was once highly valued for use in perfume. includes anchovy, hake, saury, and rockfish. NORTHERN ELEPHANT SEAL Mirounga angustirostris The largest of the pinnipeds, the northern elephant seal breeds range from central Baja California to the Farallon Islands near San Francisco. Some animals have been observed to the north during the nonbreeding season. Small groups of northern elephant seals are found at haul-out ............... areas along the Oregon coast in summer. Male elephant seals grow to 4.9 meters (over 16 feet) and weigh A between 1,800 and 2,300 kilograms (roughly two and one-half tons). Females may attain 3.3 meters and 800 kilograms. The adult male has a pronounced proboscis which begins to develop at about five years of age. It is used during trumpeting vocalizations to establish and maintain dominance among males during the breeding season. (Fop_pol'5F_@ 2 Elephant seals feed in both nearshore and offshore waters on bottom Af&- PomF-P-, /?,6& and midwater fish, squid, small sharks, and skates. Figure 80. Ancestral Porpoise VVI The skeleton and form of this 30-million-year-old porpoise is very KILLER WHALE Orcinus orca similar to the modem porpoises found in the Pacific Ocean off Killer whales are found throughout the Pacific Ocean. Subarctic con- Oregon. Propulsion is provided by the horizontal tail flukes and steering by the short, broad front flippers. centrations include those in the inland sounds of Alaska, British Colum- bia, and Washington. Also known as orcas, they travel in small groups or pods, although larger pods of 50 or more have been observed. Figure 81. Beached Sperm Whales, June 17-18, Breeding may occur throughout the year but is apparent in the spring and summer off the Washington coast. Orcas feed primarily on fish and MINKE WHALE Balaenopter'a acutorostrata 1979, Near Florence, Oregon marine mammals. Minke whales are small; the adult female averages eight meters (roughly (photo courtesy Bruce Mate, OSU Marine Science Center) The largest member of the dolphin family, orcas are distinguished by 26 feet) in length. Minkes are cosmopolitan in their distribution, and at Scientists remain unsure why whales occasionally stray onshore. their striking coloration; their backs are black and their bellies white from least three stocks are recognized in the North Pacific. In the eastern The death of this pod of sperm whales, stranded in the dry sand of the lower jaw to the anal region, extending up the flank behind the large Pacific, minke whales are found from the Chukchi Sea to central Baja the Oregon Dunes National Recreation Area near Florence, posed a large cleanup problem for officials. dorsal fin. On males, this dorsal fin may reach two meters (over six feet) California. Their winter range extends from the central California coast to in height, but on females and immature males it is less than one meter. near the equator with the greatest abundance around the Channel Islands near Santa Barbara, California. BLUE WHALES Balaenoptera musculus As with most cetaceans, minkes reach sexual maturity relatively late, at In the eastern North Pacific, blue whales range from the Aleutian Islands about seven to eight years of age. Females give birth every other year. to the central California coast during summer and from central Baja Minkes feed primarily on euphausiids and small fishes. Killer whales are California south to near the equator in winter. They are most likely to be common predators on minkes in the North Pacific. seen off the Oregon coast from late May through June and from August to October. Females give birth to a single calf once every two to three years. Prior to and during the peak of the whaling industry in the 1930s, females matured at ten years of age. In response to this exploitation, the age of sexual maturity dropped to six or seven years. The principal food of the blue whale is euphausiids (krill). Estimates from the Antarctic indicate that each blue whale consumes 4,000 kilograms (over four tons) of krill per day. (no.) H&HORE BOROO AND HANN&LO HUMPBACK WHALE Megaptera novaeangliae The humpback whale migrates from its major breeding grounds off Hawaii and both coasts of Baja California to summer feeding grounds which range from Southern California as far north as the Chukchi Sea in the Arctic Ocean. The humpback was once caught off the Pacific Northwest coast during the summer months. Humpbacks mate during the winter; gestation is 12 to 13 months. Calves are born the following year. Sexual maturity is thought to occur between 6 and 12 years of age, They arqa probably best known for their aerobatics and underwater vocalizations. Their diet consists of benthic and pelagic euphausiids and small schooling fish. While feeding off southeast Alaska, humpbacks have been observed using a technique called "bubble net feeding." The whale swims in increasingly tighter circles around its prey releasing bubbles of air. Their prey, confined by the bubbles, concentrate in a ball. The whale then rises through the center of the ball of fish with its jaws wide open to emerge with its throat grooves bulging with water and fish. Figure 82. Humpback Cow and Calf The body of the highly nomadic humpback whale is built for cruising long distances, Calves stay close to the mother during these long journeys. Comparison among photographs of the char- acteristic markings and shapes of individual tail flukes pho- tographed in Alaska, Hawaii, and Baja California, allow scientists to determine the range of migration. Nineteenth and twentieth century whaling brought the humpback close to extinction but an intema- tional treaty in 1966 banned commercial hunting of humpbacks. Scientists report that numbers of humpbacks are now increasing. GRAY WHALE Eschrichtius robustus Gray whales undertake the longest known migration of any marine mammal, traveling from feeding grounds in the Chukchi, Beaufort, and Bering Seas to calving lagoons of Baja California. The southern migration takes place from November through February; the northern portion occurs from February through May. The gray whale travels in slow-moving pods of several animals. While off the Oregon coast, most gray whales travel within 10 kilometers (6 miles) of the shoreline. Gray whales may reach lengths of up to 14 meters (45 feet). Females calve every other year in the winter following a gestation period of 13 months. The gray whale population in the eastern Pacific is estimated to be 17,000, close to its prewhaling number (7). Although it is currently on the U.S. endangered species list, an annual commercial quota of approximately 300 has been established. Some are taken by Soviets in the Bering Sea and some are taken for subsistence purposes by native Alaskans in the Bering and Chukchi Seas. Unlike other baleen whales, the gray whale is a bottom feeder, consum- ing amphipods, mysids, molluscs, and polychaete worms. These whales use their tongue to suck bottom sediments into their mouth, trapping the small benthic animals in the baleen and expelling the sediments. Occasionally gray whales may feed in the nearshore area along the coast. REFERENCES ADDITIONAL REFERENCES Pierson, M. 0., M. L. Bonnell, and G. D. Farren. 1982. Pinniped Findings. Pages 15-57 in Marine Mammal and Seabird Study-Central and Northern California, Bureau of Land References are cited in the text by number. References marked with an asterisk (*) are Bayer, R., editor. 1977. Birds of Lincoln County, Oregon. Sea Grant Marine Advisory Management, Pacific OCS Office, Los Angeles, California, POCS Tech, Paper No, 82-01. recommended. Program, Oregon State University Hatfield Marine Science Center, Newport, Oregon. Ray, G. C. 1981. The Role of Large Organisms. Pages 397-413 in A. R. Longhurst, editor, 1 .*Angell, T., and K. C. Balcomb. 1982. Marine Birds and Mammals of Puget Sound. Berland, G. A., and J. M. Scott. 1979. Checklist of the Birds of Oregon. Oregon State Analysis of Marine Ecosystems. Academic Press, London. Universit@ of Washington Sea Grant Publication, Seattle, Washington. University Book Store, Inc., Corvallis, Oregon. Rice, D. W., and A. A. Wolman. 1979. The Life History and Ecology of the Gray Whale 2. Beccasio, A. D., J. S. Isakson, A. E. Redfield, et al. 1981. Pacific Coast Ecological Browning, M. R., and W. W. English. 1972. Breeding Birds of Selected Oregon Coastal (Eschrichtius robustus). Am. Soc. Mammal. Spec. Publ. 3. Inventory: User's Guide and Information Base. U.S. Fish and Wildlife Service, National Islands. Murrelet 5:1-7. Schevill, W. E., editor. 1974. The Whale Problem: A Status Report. Harvard University Press, Coastal Ecosystems Team, Slidell, Louisiana. Haley, D. 1978. Marine Mammals of Eastern North Pacific and Arctic Waters. Pacific Search Cambridge, Massachusetts. 3. Brown, R. 1985. Personal communication. Oregon Department of Fish and Wildlife, Press, Seattle, Washington. Spalding, D. J. 1964. Comparative Feeding Habits of the Fur Seal, Sea Lion, and Harbor Newport, Oregon. Gabrielson, 1. N., and S. G. Jewett. 1940. Birds of Oregon. Oregon State College, Corvallis, Seal on the British Columbia Coast. Journal of the Fisheries Research Board of Canada 4. Eltzroth, M. S., and F. L. Ramsey. 1979. Checklist of the Birds of Oregon (Third edition). Oregon. 146. Audubon Society of Corvallis, Corvallis, Oregon. Giesler, J. D. 1952. Summering Birds of the Cape Arago Region, Coos Bay, Oregon. M.S. Tillman, M. F. 1975. Assessment of North Pacific Stocks of Whales. Marine Fishery Review 5. Graybill, M., J. Hodder, and R. Pitman. In press. Catalog of Oregon Seabird Colonies, Thesis, Oregon State College, Corvallis, Oregon. 37:1-4. U.S. Fish and Wildlife Service, Portland, Oregon. Kenyon, K. W. 1975. The Sea Otter in the Eastern Pacific Ocean. Dover, New York. 6. Laughlin, T. R., D. J. Rugh, and C. H. Fiscus. 1984. Northern Sea Lion Distribution and Kenyon, K. W., and D. W. Rice. 1961. Abundance and Distribution of the Stellar Sea Lion. J. Abundance: 1956-80. Journal of Wildlife Management 48(3):729-740. Mammal. 42223-234. 7. Marine Mammal Protection Act 1972. Annual Report 1983-84. June 1984, U.S. Depart- Leatherwood, J. S., and R. R. Reeves. 198 1. Whales, Dolphins, and Porpoises of the Eastern ment of Commerce, National Oceanic and Atmospheric Administration, National North Pacific: A Guide to Their Identification. NOAA Tech Rep. NMFS Circ. 444, National Marine Fisheries Service, Washington, D.C. Marine Fisheries Service, Washington, D.C. 8. Mate, B. R. 1981. Marine Mammals: Pages 372-457 in C. Maser, B. Mate, J. Franklin, Mitchell, E. 1974. Present Status of Northwest Fin and Other Whale Stocks. Pages 108-169 and C. Dryness, editors. Natural History of Oregon Coast Mammals. U.S. Forest in W. Scheveill, editor. The Whale Problem. Harvard Univ. Press, Cambridge, Mas- Service General Technical Report PPNW-133, Pacific Northwest Forest and Range sachusetts. Experiment Station, Portland, Oregon. Morejohn, G. V., J. T. Harvey, and L. T. Krasnow. 1978. The Importance of Loligo 9. Merrick, R, 1985. Personal communication. National Marine Fisheries Service, Seattle, opalescens in the Food Web of Marine Vertebrates in Monterey Bay, California. Calif. Dept. Washington. Fish and Game Bull. 169:67-98. 10. *Peterson, R. T. 1961. A Field Guide to Western Birds. Houghton Mifflin Company, Boston, Massachusetts. 11. Romer, A. S. 1966. Vertebrate Paleontology. The University of Chicago Press, Chicago, Illinois. 12. Sowls, A. L., A. R. DeGange, J. W. Nelson, and G. S. Lester. 1980. Catalog of California Seabird Colonies. U.S. Fish and Wildlife Service, Biological Services Program, FWS/ OBS 37/80. 13. Tyler, W. B., D. B. Lewis, K. T. Briggs, and K. F. Dettman. 1982. Seabird Findings: Pages 145-206 in Marine Mammal and Seabird Study-Central and Northern Califor- nia. U.S. Department of Interior, Bureau of Land Management. 14. Valencic, J., and R. Valencic. 1975. Whale Watcher's Guide. Dana Point, California. 15. Varoujean, D. H., and R. L. Pitman. 1979. Oregon Seabird Colony Survey 1979. U.S. Department of Interior, Fish and Wildlife Service, Portland, Oregon. 16. Varoujean, D. H. 1984. Personal communication. University of Oregon Institute of Marine Biology, Charleston, Oregon. 17. Walker, T. J. 1975. The Whale Primer. Cabrillo Historical Association, San Diego, California. 18. Wiens, J. A. and J. M. Scott. 1975. Model Estimation of Energy Flow in Oregon Coastal Seabird Populations. Condor 77:439-452. (02) n .1, Z%FV)EH[U)@K A@ I WEIGHTS AND MEASURES MASS MORE INFORMATION LENGTH 1 milligram (mg) = 0.000035 ounce (oz) The interested reader may want to track down additional detail on a 1 micrometer (um) = 0.000001 meter (m) 1 gram (g) = 0.0353 ounce particular subject presented in the Oceanbook or may want to expand 1 millimeter (mm) = 0.001 meter 1 kilogram (kg) = 2.205 pounds (lb) into an area not covered here. The references at the end of each chapter 1 metric ton (MT) = 1,000 kilograms should help provide direction to specific literature. However, it may be 1 millimeter = 0.0394 inch (in) 1 metric ton = 2,205 pounds appropriate to contact some experts in the field of interest to clarify a 1 centimeter (cm) = 0.01 meter 1 metric ton= 1. 1 tons point or to provide additional information. The following list will assist I centimeter = 0.3937 inch I pound = 0.454 kilogram those interested in making contact with such experts. 1 meter (m) = 3.281 feet (ft) 1 ton (t) = 9.07 kilograms Oregon State University, Corvallis, Oregon 97331 1 kilometer (km) = 3,281 feet 1 kilometer = 0.6214 miles (mi) FLOW RATES College of Oceanography: (503) 754-3504 1 inch = 25.40 millimeters Oceanography Library: 754-2236. 1 inch = 2.54 centimeters 1 cubic meter/second (m/s) = 35.31 cubic feet/second (cfs) Sea Grant College Program: 754-2714 1 foot = 0.3048 meter 1 cubic meter/second = 15,852 gallons/minute (gpm) Mark 0. Hatfield Marine Science 1 mile= 1.609 kilometers 1 cubic foot/second = 0.0283 cubic meter/second Center, Newport (503) 867-3011 1 mile = 0.869 nautical miles 1 cubic foot/second = 448.8 gallons/minute University of Oregon 1 fathom (f m) = 6 feet 1 fathom = 1.829 meters TEMPERATURE Institute of Marine Biology, Charleston, Oregon 97420 Administration/Information (503) 888-5534 AREA C = degrees Celcius or Centigrade Ocean and Coastal Law Center, C = ( F - 32) x 5/9 Eugene (503) 686-3866 1 square meter (m) = 10.765 square feet (ft) On the Celcius scale, water freezes at 00 University of Washington, Seattle, Washington 98195 1 hectare= 10,000 square meters and boils at 1000. 1 hectare= 2.471 acres College of Ocean and Fisheries 1 square kilometer (km) = 0.386 square mile F = degrees Farenheit Sciences (206) 543-6605 1 square kilometer = 247.1 acres F = Cx9/5 + 32 Sea Grant Program 543-6600 1 square kilometer= 100 hectares (ha) On the Farenheit scale, water freezes at 32' State of Oregon 1 square foot = 0.0929 square meter and boils at 212'. Department of Fish and Wildlife 1 acre (ac) = 4,047 square meters Fish Division, Portland (503) 229-5669 1 acre = 0.4047 hectares Marine Region, Newport (503) 867-4741 1 acre= 0.00156 square mile 1 square mile = 640 acres Department of Geology and Mineral Industries 1 square mile = 2.59 square kilometers State Geologist, Portland (503) 229-5580 1 square mile = 259 hectares Department of Land Conservation and Development Director/Information, Salem (503) 378-4926 VOLUME 1 cubic meter (m) = 35.31 cubic feet (ft) MORE OCEANBOOKS 1 cubic meter = 264.2 gallons (gal) 1 liter (1) = 0.03531 gallon contact: 1 liter= 0.001 cubic meter Bookstore 1 cubic foot (ft) = 0.0283 cubic meter Hatfield Marine Science Center 1 cubic foot = 7.48 gallons Oregon State University 1 gallon = 0.003785 cubic meter Newport, Oregon 97365 (503) 867-3011 no 3 6668 00 04 3564