Status of living marine resources off Alaska, 1993

[From the U.S. Government Printing Office, www.gpo.gov]

S141 OF C-0
S@
NOAA Technical Memorandum NMFS- AFSC-27
J
SPqrE S'Of
Status of Living
Marine Resources off
Alaska, 1993

SH
11 January 1994
.A2
N62
11@
it

AhL

AAbh

1994

NOAA Technical ME!morandum NMFS

The National Marine Fisheries Service's Alaska Fisheries Science Center
uses the NOAA Technical Memorandum series to issue informal scientific
and technical publications when complete formal review and editorial
processing are not appropriate or feasible. Documents within this series
reflect sound professional work and ma@ be referenced in the formal
scientific and technical literature.

The NMFS-AFSC Technical Memorandim series of the Alaska Fisheries
Science Center continues the NMFS-F/NWC series established in 1970 by
the Northwest Fisheries Center. The now NMFS-NWFSC series will be used
by the Northwest Fisheries Science Center.

This document should be cited as follows:

Low, Loh-Lee. (coordinator) 19,33. Status of living marine resources
off Alaska, 1993. U.S. Dep. Corimer., NOAA Tech. Memo. NMFS-
AFSC-27, 110 p.

Reference in this document to trade names does not imply endorsement by
the National Marine Fisheries Service, IqOAA.

This document Is available to the public through:

National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161

NOAATechnical Memorandum NMFS-AFSC-27

ENT Orr

Status of Living Marine
Resources off Alaska, 1993

Alaska Fisheries Science Center
7600 Sand Point Way N.E., BIN C-1 5700
Seattle, WA 98115-0070

U.S. DEPARTMENT OF COMMERCE
Ronald H. Brown, Secretary
National Oceanicand Atmospheric Administration
D. James Baker, Under Secretary and Administrator
National Marine Fisheries Service
Rolland A. Schmitten, Assistant Adminstratorfor Fisheries

C"
January 1994
LIBRARY
NOAA/cCEH
1990 HOBSON AVE.
'HAS. SC 29408-2623

CONTRIBUTORS

This report was written primarily by scientists at the Alaska Fisheries Science Center, National Marine
Fisheries Service, with some contributions from the Alaska Department of Fish and Game and the Interna-
tional Pacific Halibut Commission. The following personnel were the major contributors:

Technical Editors: Loh-Lee Low, James C. Olsen, and Howard W. Braham.

Section Contributors:
Groundfish Resources Section: Vidar G. Wespestad, Grant G. Thompson, Anne B. Hollowed,
Looh-Lee Low, Sandra A. Lowe, Thomas K. Wilderbuer, Terrance M. Sample, Gary E. Walters,
Daniel 11 Ito, James N. Ianelli, Harold H. Zenger, Jr., Eric S. Brown, Jeff-fey T. Fujioka,
David M. Clausen, Jonathan Heifetz, Victoria M. O'Connell, and Patrick J. Sullivan.
Pelagic Resources Section: Vidar G. Wespestad.
Shellfish Resources Section: Jerry E. Reeves.
Salmon Resources Section: James C. Olsen.
Marine Mammal Section: Howard W. Braham.

Photograph Selections: Julie A. Pearce.
Graphics: Loh-Lee Low.
Copyediting: Gary J Duker, James K. Lee, and Susan Calderon.
Publication: James K. Lee and Gary J Duker.
Coordinator Loh-Lee Low.

CONTENTS

Overview IA)h-Lee Low ................................................................ I
Bering Sea/Aleutian islands Groundfish Resources
1. Walleye, Pollock Mdar G. Vkspestad ........................................................ I I
2. Pacific Cod Grant G. Thompson ........................................................ 14
3. Yellowfin Sole Thomas K Wilderbiter .................................................... 17
4. Greenland Turbot Thomas K. Wilderbuer and Terrance X Sample ..................... 20
5. Arrowtooth Flounder Terrance M. Sample and Thomas K Wilderbuer ..................... 22
6. Rock Sole Thomas; K. Wilderbuer and Gary F. Walters .......................... 24
7. Other Flatfish Gary K Walters and Thomas K Wilderbuer .......................... 26
8. Pacific Ocean Perch Daniel H. Ito and James N. lanetli ...................................... 29
9. Other Rockfish Daniel H. Ito ................................................................ 32
10. Atka Mackerel Sandra A. Lowe ............................................................ 34
11. Squid and Other Species Loh-Lee Low .............................................................. 37
Gulf of Alaska Groundfish Resources
12. Walleye Pollock Anne B. Hollowed ......................................................... 39
13. Pacific Cod Harold H. 7enger, Jr . ...................................................... 42
14. Flatfish Thomas K. Wildertnier and Eric S. Brown .............................. 44
15. Sablefish Sandra A. Lowe and Jeffrey T Fujioka ................................. 46
16. Slope Rockfish David NL Clausen and Jonathan Heifetz ............................... 49
17. Pelagic Shelf Rockfish David K Clausen and Jonathan Heifetz ................................ 52
18. Demersal Shelf Rockfish Victoria X O'Connell and Jeffrey T. Fujioka ......................... 54
19. Thomyheads Loh-Lee Low ............................................................... 56
20. Pacific Halibut Patrick J. Sullivan .......................................................... 58
Pelagic Resources
21. Pacific Herring Vidar G. Wespestad ........................................................ 61
Shellfish Resources Jerry E. Reeves .............................................................. 65
22. King Crabs .............................................................................................. 66
23. Tanner and Snow Crabs .............................................................................................. 71
24. Shrimp and Sea Snails .............................................................................................. 74
Pacific Salmon Resources James C. 01scm ............................................................. 77
25. Chum Salmon ..................................................................................... ......... 79
26. Pink Salmon .............................................................................................. 81
27. Sockeye Salmon .............................................................................................. 83
28. Coho Salmon .............................................................................................. 85
29. Chinook Salmon .............................................................................................. 87
Marine Mammals Howard W. Braham ....................................................... 91
30. Bowhead Whale .............................................................................................. 93
31. Gray Whale .............................................................................................. 95
32. Humpback Whale .............................................................................................. 97
33. Killer Whale .............................................................................................. 99
34. Beluga Whale .............................................................................................. 100
35. Dall's Porpoise .............................................................................................. 101
36. Harbor Porpoise .............................................................................................. 102
37. Northern Sea Lion .............................................................................................. 103
38. Northern Fur Seal .............................................................................................. 105
39. Harbor Seal .............................................................................................. 107
40. Spotted Seal .............................................................................................. 109

OVERVIEW

By Loh-Lee Low

OPA

RIK ra IRA

0. 1

@Z'
@W-

X
ob
ftoto: AFSO
Status of Stocks Gulf of Alaska, pelagic resources, shellfish, salmon,
and marine mammals. There are other resources of
off the Coast of Alaska commercial and recreational importance that are not
included in this report; these are mostly inshore
marine resources under the jurisdiction of the State
This report provides a species-by-species descriP- of Alaska.
tion of the status of living marine resources off
Alaska as assessed for 1993. The descriptions are Alaska FisherlesSclence Center
for resources that are primarily under the research
and management jurisdiction of the National Marine The Alaska Fisheries Science Center (AFSC) is
Fisheries Service (NMFS), National Oceanic and responsible for research on living marine resources
Atmospheric Administration, U.S. Department of in Federal waters off Alaska and parts of the West
Commerce. The report was prepared by scientists Coast of the United States. This region includes the
from the NMFS' Alaska Fisheries Science Center, northeast Pacific Ocean and the eastern Bering Sea,
the Alaska of Fish and Game (ADF&G) and the which support some of the most important commer-
International Pacific Halibut Commission (lPHC). cial fisheries in the world for Pacific salmon, walleye
It is one of a series of regional reports on the status pollock, Pacific cod, sablefish, flounders, rockfishes,
of living marine resources throughout the United and crabs. The region also supports popular sport
States. fisheries for Pacific salmon, halibut, and steelhead
The resources are grouped under six major trout and is home to an array of marine mammal
headings: groundfish resources of the Bering Sea/ species.
Aleutian Islands region, groundfish resources of the

Overview

65N 140' 150' 160' 170'E 180' 170'W 160' 150' 140' 130' 120' 110' 65'N

U.S.S.R.
ALASKA

60'
60'

Bering
Sea

50'
50'

Pacific
P A C I F I C 0 C E A N Coast
40' 40'
U.S.A.

30'
30'

20o 20'

140' 150' 160' 170'E 180' 170' W 160' 150' 140' 130 120' 110'

The range of distrubution of marine resources native to Alaska

The mission of the AFSC is to conduct research fisheries from the early 1950s until the enactment of
programs to generate the best scientific data for the Magnuson Fishery Conservation and Manage-
better understanding the region's resources and the ment Act (MFCMA) in 1977. The implementation
environmental quality essential for their existence. of the MFCMA led to an extremely successful
The Center provides scientific data and technical development of the domestic groundfish industry off
advice to its constituents for better utilization and Alaska. Under the MFCMA, joint ventures with
management of these living marine resources. The foreign countries were first formed to involve
Center's primary constituents are the Pacific and domestic fishermen in the fisheries. Within a short
North Pacific Fishery Management Councils, NMFS 3-5 years, most of these joint ventures became
headquarters and regional offices, State and Federal purely domestic operations. Thus a thriving domes-
agencies, international fisheries commissions, the tic groundfish industry was born.
fishing and fish processing industry, and the general Under the MFCMA, the groundfish resources
public. became subject to management by the North Pacific
Fishery Management Council (NPFMC) under two
Groundfish Resources fishery management plans (FMPs): one for the
Bering Sea/Aleutian Islands region and the other for
The productive waters off the coast of Alaska the Gulf of Alaska.
support some of the world's largest populations of The long-term potential yield (LTPY) for all
groundfish. Large-scale commercial fisheries for groundfish resources off Alaska (Bering Sea/
groundfish were developed and dominated by foreign Aleutian Islands region plus the Gulf of Alaska)

2 Overview

Fisheries Resources off Alaska

Species Recent Average Current Long-term
Group Yield (t) Potential Potential
(1990-92) Yield (t) Yield (t)

-----------------------------------------------------------------
Groundfish (BSAI) 1,664,710 2,422,495 2,909,500
Groundfish (GOA) 222,760 734,550 451,070
Pacific Halibut (U.S.) 31,000 29,000 30,000
Pacific Herring 45,860 45,100 Unknown
Shellfish 125,220 125,220 95,370
Salmon 320,500 282,200 282,200

Total 2,410,050 3,638,565 3,813,240

totals more than 3.39 million metric tons (t). The and Pacific cod. The abundances of flatfishes; and
current potential yield (CPY) of 3.19 million t is Pacific cod are high. Pollock and sablefish abun-
close to LTPY, reflecting excellent condition of the dances are at average levels. The abundances of all
stocks. For the Bering Sea/Aleutian Islands region, rockfishes are generally low. The LT?Y for Gulf of
the average groundfish catch in recent years (1990- Alaska groundfish is 451,000 L The CPY is
92) was about 1.66 million t; the 1992 catch of 735,000 t, well above LTPY because flatfishes are
1.76 million t had an ex-vessel value above particularly abundant. The RAY was 222,700 t,
$522 million. For the Gulf of Alaska the average indicating that the Gulf of Alaska groundfish
1990-92 catch was 222,800 t; the 1992 catch of resources are still substantially underutilized.
213,000 t had an ex-vessel value of $133 million. In addition to the general groundfish complexes,
For the Bering Sea/Aleutian Islands region, the Pacific halibut is a groundfish species that has
major species groups harvested are walleye pollock supported an important traditional fishery for the
(77%), Pacific cod (10%). flatfishes (9%), Atka United States and Canada. The resource is fully
mackerel (1.8%), rockfishes (0.9%), and sablefish utilized and managed by IPHC. The LTPY for the
(0.2%). Except for Greenland turbot, all the entire Pacific halibut resource totals 30,000 to
groundfish species are high in abundance and in 36,000 t; the portion in U.S. waters is about 30,000
excellent condition. The LTPY or maximum L The CPY in U.S. waters is 29,000 t, reflecting the
sustainable yield (MSY) for the complex is about generally good condition of the resource. Recent
2.91 million L The CPY of 2.42 million t is 17% average catches (1990-92) were 31,000 t in U.S.
below LTPY, which mostly reflects lower abundance waters and, including Canada, were 35,700 L
of walleye pollock in recent years.
The major species groups harvested in the Gulf of Pelagic Resources
Alasks, are walleye pollock (37%), Pacific cod
(34%), sablefish (10%), flatfishes (9%), and slope In the Gulf of Alaska, major concentrations of
rockfish (8%). Overall abundance of groundfish in Pacific herring occur in Southeast Alaska, Prince
the Gulf of Alaska has been relatively stable. The William Sound, and Kodiak Island-Cook Inlet. In
most abundant species in the Gulf are flatfishes, the Bering Sea, they occur in Northern Bristol Bay
particularly arrowtooth flounder, followed by pollock and Norton Sound. In the Chukchi Sea and Arctic

Overview 3

Bering Sea-Aleutian Islands Groundfish Resources

Species Recent Average Current Long-term Status of
Yield (t) Potential Potential Utilization
(1990-92) Yield (t) Yield (t)
------------------------------------------------------------------------------
Pollock 1,281,000 1,398,700 1,944,600 Full
Pacific cod 170,300 164,500 143,000 Full
Yellowfin sole 90,400 238,000 220,000 Full
Greenland turbot 5,800 7,000 27,100 Full
Arrowtooth flounder 5,600 72,000 59,000 Under
Rock sole 29,900 185,000 160,200 Under
Other flatfish 12,100 191,000 148,500 Under
Sablefish 3,270 4,100 10,900 Full
Pacific ocean perch 14,500 17,170 14,900 Full
Other rockfish 930 1,325 1,300 Full
Atka mackerel 30,260 117,100 117,100 Full
All Others 20,650 26,600 62,900 Under

TOTAL 1,664,710 2,422,495 2,909,500

Gulf of Alaska Groundfish Resources

Species Recent Average Current Long-term Status of
Yield (t) Potential Potential Utilization
(1990-92) Yield (t) Yield (t)
------------------------------------------------------------------------------
Pollock 81,400 160,000 169,000 Under
Pacific cod 76,680- 56,700 56,700 Full
Sablefish 21,600 20,800 23,500 Full
Slope rockfish 17,470 21,580 21,580 Full
Flatfish 21,160 466,750 169,000 Under
Thornyhead rockfish 1,500 1,180 3,750 Unknown
Pelagic shelf rockfish 2,480 6,740 6,740 Full
Demersal shelf rockfish 470 800 800 Full

TOTAL 222,760 734,550 451,070

Ocean, abundance is low and commercial concentra- In the Gulf of Alaska, stocks am at moderate to
tions of Pacific herring have only been located in high abundance levels and the outlook is for in-
Kotzebue Sound. The fishery takes place in inshore creases as a strong 1988 year class recruits to the
areas. fisheries. In the Bering Sea, Pacific herring stocks
The LT?Y for Pacific herring off Alaska is not declined through the 1980s as the very strong 1977-
known because stock abundance is highly variable. 78 year classes which sustained the fisheries aged
The CPY is about 45,100 L The 1992 total Pacific and declined in abundance. In 1992, a strong 1988
herring harvest of 56,400 t (23,850 t in the Gulf of year class recruited into the fishery and those fish
Alaska and 32,550 t in the Bering Sea) had an ex- should further increase abundance of the stocks in
vessel revenue of $30 million. The majority of the 1993.
harvest was roe herring and the remainder was food
and bait herring and roe-on-kelp.

4 Overview

Shellfish Resources 1992 catch in the Gulf of Alaska was about 900 t'
worth about $680,000. Shrimp catches used to be
T'he king and Tanner crab fisheries we currently fairly large in the Bering Sea in the early 1960s
the most important shellfish fisheries off Alaska (32,000 t in 1963). The fishery ceased operation in
71iree species of king crab (red, blue, brown or 1973 after the resource was depleted by foreign
golden) and two species of Tanner crab fisheries.
(Chionoecetes bairdi and C. opilio) are harvested The sea mail stocks are located primarily in the
commercially. Historically, red king crab has eastern Bering Sea shelf. Ile stock is underutilized
predominated in king crab landings. In recent years, because the fishery for sea mails is undeveloped.
blue and brown king crab have become relatively The status of the snail stocks is not clear, although
more importanL resources are known to be generally abundanL
During the developmental phase of the Tanner Besides the major shellfish resources summarized
crab fishery, C. bairdi dominate the landings. In above, fishermen also harvest the following shellfish
more recent years, there has been a shift in species resources mostly within State waters: Dungeness
composition; the C. opilio catch is currently 10- crab, Korean horse hair crab, sea cucumber, sea
times the C. bairdi catch. urchin, scallop, abalone, geoduck, and octopus. The
The annual ex-vessel value of Alaskan king and combined value of these catches in 1992 (4,W t)
Tanner crab fisheries averaged $195 million during was $13 million.
the 1978-90 period. The 1992 value was
$287 million; 25% ($70 million) was attributable to Salmon Resources
king crab and the rest to Tanner crab. The Bering
Sea crab stocks are jointly managed by the State of There are five species of Pacific salmon: chum,
A]-q.qk-q and the Federal government under an FM[P pink, sockeye, coho, and chinook salmon. Pacific
of the NPFMC. Gulf of Alaska crab and shrimp salmon are anadromous; they spawn in fresh water,
resources are managed by the State of Alaska migrate and rear in the open ocean, and return to
The U.S. fishery for shrimp in Alaskan waters is their home stream or lake to repeat the life cycle.
currently at a low level. The western Gulf of Al-asksk The Pacific salmon fishery in Alaska contributes
has been the main area of operation. From the significantly to the food supply and economy of the
1960s, catches rose steadily to about 58,000 t in Nation and ranks as the largest non-government
1976, and declined precipitously after that time. employer in Alaska with sales exceeding those of
During the 1960-90 period, the ex-vessel value of tourism, mining, or forest products. The fishery
western Alaska shrimp fisheries averaged $4 million provides adundant recreational opportunities and is
annually, with a peak value of $14 million in 1977. an integral part of Alaska native culture and heri-
Since 1988, shrimp catches have been minor. The tage. Recent catches (1990-92) exceed 155 million

Pacific Herring Resource

Species Recent Average Current Long-term Status of
Yield (t) Potential Potential Utilization
(1990-92) Yield W Yield (t)

------------------------ ---------------------------------------------------
Bering Sea-Aleutians 23,230 28,200 Unknown Full
Gulf of Alaska 22,630 16,900 Unknown Full

Total 45,860 45,100 Unknown Full

Overview 5

Pacific Halibut Resource

Species Recent Average Current Long-term Status of
Yield (t) Potential Potential Utilization
(1990-92) Yield (t) Yield (t)
---------------------------------------------------------------------------------
Bering Sea-Aleutians 3,600 2,800 --- Full
Gulf of Alaska 27,200 25,900 --- Full
Pacific Coast 200 300 --- Full
Off Canada 4,700 4,500 Full

Total 35,700 33,500- 30,000-36,000 Full
U.S. Total 31,000 29,000

Higher by 16,000 t if sports catch, bycatch, and waste are included.

Alaska Shellfish Resources

Species Recent Average Current Long-term Status of
Yield (t) Potential Potential Utilization
(1989-91) Yield (t) Yield (t)
----------------------------------- ---------------------------------------------

King crabs 12,710 12,710 27,070 Full
Tanner crabs 112,510 112,510 40,900 Full
Shrimp 0 300 22,600 Full
Sea snails 0 1,800 4,800 Under

Total 125,220 125,220 95,370

Alaska Salmon Resources

Curient
Species Recent Average Potential Long-term Status of
Yield (t) Yield (t) Potential Utilization
(1990-92) (1980-92) Yield (t)
---------------------------------------------------------------------------------
Pink 127,300 113,200 113,200 Full
Sockeye 138,900 109,000 109,000 Full
Chum 31,700 38,200 38,200 Full
Coho 17,800 16,100 16,100 Full
Chinook 4,800 5,700 5,700 Full

Total 320,500 282,200 282,200 Full

fish or 320,500 L Ex-vessel value of the 1992 catch complex niixture of domestic and international
was about $575 million. bodies, treaties, regulations and agreements. The
Management of Pacific salmon in Alaska's vast State of Alaska has prime responsibility for manag-
marine area with a coastline of nearly 34,000 miles ing the Pacific salmon resource, where most of the
is accomplished by Federal and State agencies in a fishery takes place inshore. Management in the U.S.

6 Overview

Exclusive Economic Zone (EEZ) is the
responsibility of NMFS and the Status of Resident and Selected Species
NPIFMC. of Marine Mammals off Alaska'
Recreational fishing is permitted in
all regions of the EEZ off Alaska under
ADF&G regulations. The recreational Species Trends
catch in the EEZ is probably less than Abundance (% Change)
several hundred salmon with most -----------------------------------------------------
taken in the charter boat fishery. The Bowhead whale 7,500 +3.1/yr
(1978-88)
statewide sport catch within State
waters in 1990 was about 909,000 fish. Gray whale 20,869 +3.3%/yr
The five species of Pacific salmon (19,737-22,489) (1968-88)
are fully utilized. The stocks have Humpback whales >2,000 Unknown
generally rebuilt to or are beyond
previous high levels. On a regional Killer whale >300 Unknown
basis, some stocks may be overutilized Beluga 15,800-18,450 Unknown
because of mixed stocks in the catch.

Dall's porpoise 300,000-600,000 Unknown
Marine Mammal Resources
Harbor porpoise Unknown Unknown

Forty-two species of marine Northern sea lion >34,844 -70%
mammals in U.S. waters of the North
Pacific Ocean are under the jurisdic- Northern fur seal 982,000 -50%
tion of the U.S. Department of Com- (1975-90)
merce. These include 31 species of Harbor seal Uncertain -60%
whales, dolphins and porpoises, and (<1001000) (1976-92)
11 species of seals and sea lions. Six Spotted2 seal Unknown Unknown
species are found only in Alaska.
Fourteen of the most commonly
observed species of marine mammals
are normally found close to shore. The Bowbead, gray, and humpback whale estimates
are for the entire eastern North Pacific
other species usually remain in Ocean; all others are for Alaska.
offshore waters, on remote islands, or 2 Other ice-associated seals are the bearded,
am rare in number and seldom seen. ribbon, and ringed seals.
Most marine mammals make long-
distance migrations or move thousands of miles under the Marine Mammal Protection Act (MI@IPA)
within smaller areas of the ocean between seasons of of 1972 and the Endangered Species Act (ESA) of
the year. These movements occur when marine 1973.
mammals, especially whales and dolphins, travel
Erom one feeding ground to another or spend the
breeding season in lower latitudes and the major
feeding and calf-rearing seasons in higher latitudes.
There are several populations of marine mam-
mals that only spend a portion of the year in Alaska,
such as humpback whales and northern fur seals,
whereas others are found year-round inAlaska, such
as the bowhead whale. These zoogeographic
differences have lead to unique life history strategies
and result in the need to manage accordingly.
Management of marine mammals is carried out

Overview 7

-WK

_L_ Al

Photo: 1PHC

Glossary of Common
Abbreviations and Terms

MFCMA Magnuson Fishery Conservation and ABC Acceptable biological catch. A catch
Management Act of 1976. level that can be justified on biological and ecologi-
ESA Endangered Species ACL cal grounds without reference to social or economic
MMPA Marine Mammal Protection ACL factors. Scientists use various mathematical meth-
NMF'S National Marine Fisheries Service. ods to estimate ABC, depending on the stock type
NOAA National Oceanic and Atmospheric and available data. Similar to current potential yield
Administration. (CPY).
AFSC Alaska Fisheries Science Center
NWFC Northwest Fisheries Science Center LTPY -- Long-term potential yield: The maxi-
SWFC Southwest Fisheries Science Center mum long-term average yield (catch) from the
ADFG Alaska Department of Fish and Game resource. It is similar to maximum sustainable yield
NPFMC North Pacific Fishery Management (MSY).
Council
PFMC Pacific Fishery Management Council CPY -- Current potential yield: The current catch
INPFC International North Pacific Fisheries that may be obtained from the resource. It is similar
commission. to acceptable biological catch (ABC) which mea-
CalCOF1 California Cooperative Oceanic sures the biological production potential of the stock.
Fisheries Investigations.
IEPHC International Pacific Halibut RAY -- Recent average yield: This is current
Commission average catch, denoted usually by a specific time
CO.'

period.

8 Overview

TAC -- Total allowable catch: Total allowable F0.1 is a point at which the increase in yield for
catch is the total regulated catch from a stock in a increased effort is 10% of what it was when fishing
given time period, usually a year. mortality was very low.

Mortality rates: The rate at which fish die from F,,,, is the fishing mortality rate that reduces
natural causes or through fishing. Mortality rates spawning biomass per recruit ratio to 35% of the
can be described in several ways. The easiest--total unfished level. This rate has often been adopted by
annual mortality rate--defines the fraction of the fish the PFMC and NPFMC as the fishing rate to
within a group that die during the year. These rates calculate ABC. The F3,,, has often been adopted as
are difficult to use mathematically when describing the F...... rate.
the relative contribution of different types of natural
or fishing mortality to the total mortality of fish CPUE - Catch per unit effort: This is an index of
during a year. Thus, instantaneous mortality is used. stock abundance.
Instantaneous mortality rate: An instantaneous Recruitment: The amount of fish, in numbers or
mortality rate is the fraction of the population of fish weight, that reach a certain size or age in a specific
that dies in a very short (instantaneous) period of year. For example, all fish reaching their second
time. There is a relatively simple mathematical year would be age-2 recruits. This is often used to
conversion between instantaneous rates and annual describe the strength of a year class.
rates. For example, the total instantaneous mortality
rate, often denoted by Z, is equivalent to the annual Year class (or cohort): Fish of the same stock born
rate A, according to the formula: A = 1 - e-z . in the same year. Occasionally a stock produces a
very small or very large year class and tins group of
M -- Natural mortality is the mortality due to fish is followed closely by assessment scientists since
natural causes. it can be pivotal in determining the stock abundance
F -- Fishing mortality is the mortality due to in successive years.
fishing.
Z -- Total mortality rate is the combined effect of Population: An interbreeding group of living marine
all sources of mortality acting on a fish population. organisms, such as a species in a geographic area.
Thus Z = M + F.
Stock: A portion of the population that is reason-
Reference fishing mortality rates: There are ably well mixed and is geographically distinct in
specific rates of F that measure how close a stock is terms of fishery and management.
to full exploitation. They are defined in terms of an
increase in yield from a year class over its lifespan as
fishing mortality increases. When no fish are taken,
there is no yield from the year class. As fishing
increases, the yield increases, but at a decreasing
rate.

F. is the point at which the increased yield for
additional effort is zero; that is, additional fishing
mortality will not increase yield, but in fact, may
decrease it as fish are caught before they are fully
grown.

F.., is the rate of fishing mortality when
maximum sustainable yield for the stock is achieved.

Overview 9

1, WALLEYE POLLOCK

By Vidar G. Wespestad

F
7
40

_oc

Photo: AFSC
The walleye pollock (Theragra chalcogramma) Islands region.
is the most abundant groundfish species in the Bering Sea pollock recruit to the fishery at age 3-
eastern Bering Sea/Aleutian islands region, compris- 4 years, which corresponds to their age of maturity,
ing well over 50% of the total groundfish catch. at an average size of 35-40 cm and 0.25-0.40 kg.
Total ex-vessel value of the 1.2 million t catch in The rate of natural mortality of exploited pollock is
1991 was $232 million. Walleye pollock is a 0.3 and they survive in significant numbers to age 9.
semidernersal species that is primarily pelagic Strong year classes persist to about age 16-18 years
during the first few years of life and then becomes in the commercial catch. The maximum observed
increasingly demersal in behavior as it ages. age for pollock is 31 years. Maximum length is
The species is found in greatest abundance along 91 cm and maximum weight is 5 kg.
the outer continental shelf and slope between the 100 From 1954 to 1963, pollock were harvested at
and 500 m depth contours. Pollock migrate from low levels in the eastern Bering Sea. Directed
deep to shallow water in summer and return to deep fisheries began in 1964. Catches increased rapidly
water in autumn. They are both bottom and pelagic during the late 1960s and reached a peak of
feeders and consume plankton, krill, and fish. The 1.9 million t in 1972. Since 1977, catch quotas have
walleye pollock is highly cannibalistic, with its ranged from 950,000 to 1.3 million t. Catches in the
young a major component of its diet. They also Aleutian Islands region have always been less than
occur pelagically in deep waters of the Aleutian those in the eastern Bering Sea. Catches in this area
Basin. Stock structure of pollock has not been well increased from 1980 to 1984 due to increased
delineated. For the purpose of management within foreign effort and have decreased in recent years as
the U.S. EEZ, the resource is divided into two major the foreign fishery was phased out and domestic
regions: the eastern Bering Sea and the Aleutian fisheries began to exploit the resource.

Bering Sea/Aleutian Islands Groundfish Resources 1

WALLEYE POLLOCK
Eastern Bering Sea, Aleutian Islands and Aleutian Basin
COMMERCIAL CATCH (1,000 t)

AlpijtjAn Tq1&Q" Al aut i an
Ragin
Year Foreign JVP DAP Foreign JVP DAP Total
----------------------------------------------------------------------------
1977 978 0 0 8 0 0 986 0
1978 979 0 0 6 0 0 985 0
1979 914 0 0 10 0 0 924 0
1980 948 11 0 58 0 0 1,017 15

1981 931 42 0 56 0 0 1,029 1
1982 903 53 0 56 2 0 1,014 4
1983 835 145 1 56 3 0 1,040 71
1984 862 230 6 70 7 4 1,179 181
1985 771 370 38 51 7 1 1,238 336

1986 337 805 47 15 30 1 1,235 1,061
1987 4 1,015 218 0 28 1 1,266 1,325
1988 0 739 489 0 41 2 1,271 1,396
1989 0 227 952 0 5 11 1,195 1,399
1990 0 22 1,180 0 0 79 1,259 917
1991 0 0 1,038 0 0 79 1,117 297
1992 0 0 1,348 0 0 so 1,398 3

JVP: Joint Venture Processing DAP: Domestic Annual Processing

Two important developments occurred in the Assessment of eastern Bering Sea pollock utilizes
Bering Sea pollock fishery in the 1980s. Ile first mformation from age-structured models, bottom
was the initiation of high-seas pollock fisheries in trawl surveys, and hydroacoustic surveys. Bottom
the central Bering Sea (the "donut hole" area) trawl surveys have been conducted annually since
outside of the U.S. and Soviet'FF7- . The second 1977 and hydroacoustic surveys have been repeated
was the development of a U.S. fishery on spawning trienally since 1979. Three age-structured popula-
pollock in the vicinity of Bogoslof Island (Bering tion dynamics models have been employed to assess
Sea Area 518). In 1984, the donut hole catch was pollock: cohort analysis, a catch-at-age model
only 18 1,000 L The catch grew to a peak of (CAGEAN), and a stock synthesis model. All three
1.4 million t in 1989; this exceeded the pollock catch models show the same biomass trend, however, the
within the U.S. Bering Sea EEZ. The catch fell cohort model results are reported below to indicate
rapidly to 917,000 t in 1991 and 297,000 t in 1992. biomass levels.
The donut hole fishery ended in 1993 under terms of The abundance of pollock in the eastern Bering
a temporary (1993-94) multilateral moratorium. The Sea has risen from a low of 4.0 million t in the late
Bogoslof fishery occurs in deep water off the eastern 1970s (induced by large removals in the early to
Bering Sea shelf. In 1987 the catch was 377,000 L mid-1970s and by reduced recruitment) to a peak of
It decreased by 36,100 t in 1989, but increased to 15.8 million t in 1985. Most of the increase during
264,800 t in 199 1. In 1992, fishing in the Bogoslof the early 1980s was due to the recruitment of a very
Island area was prohibited in response to the rapid strong 1978 year class. The population has since
decline of Aleutian Basin pollock abundance; been declining following lower levels of recruitment
biological information suggests that fisheries in the in the early 1980s and aging of the 1978 year class.
Aleutian Basin and the Bogoslof Island area are A strong 1989 year class began recruiting into the
harvesting the same group of fish. fishery in 1992. This year class is expected to

12 Bering Sea/Aleutian Islands Groundfish Resources

WALLEYE POLLOCK
Eastern Bering Sea and Aleutian Islands

V.Aqt-@rn Rpriner _qAa Alpiltian Tslands

Average catch (1977-92) 1.1 million t 39,071 t
Long-term potential yield (MSY) 1.8 million t 144,600 t
Acceptable biological catch (1993) 1.34 million t 58,672 t
Fishing strategy F351 F35%
Age of recruitment 3 years
Size at recruitment 35 cm, 251 g
Maximum age 31 years
Abundance and trend Moderate-stable Unknown
Recreational importance None None
Subsistence use Minor Minor
Management BSAI Groundfish FMP
Assessment Method Age structured Trawl survey
Status of exploitation Fully exploited Fully exploited
M 0.30 0.20
FwY
0.38
F (35%. 1*931
0.37 0.42

contribute significantly to the fishery for the next For further information
few years and end the declining trend. Trawl
surveys also indicate that the 1990 and 1991 year Wespestad, V. G., and P. Dawson. 1992. Walleye
classes may be above average. If these year classes pollock. In Stock assessment and fishery evaluation
hold up, then eastern Bering Sea pollock biomass is document for groundfish resources in the Bering
expected to continue increase through the mid- Sea/Aleutian Islands region as pmjected for 1993.
1990s. Ile ABC for the eastern Bering Sea stock North Pacific Fishery Management Council, P.O.
was estimated to be 1.34 million t from a biomass of Box 103136, Anchorage, AK 99510.
5.9 million t in 1993.
Sufficient data are not available to
perform an age-structured analysis for Walleye Pollock
the Aleutian Islands stock; thus the Bering Sea/Aleutian Islands
biomass is estimated from occassional
trawl surveys. The 1993 exploitable 3.5- Catch @Million t) Biomass (Million t) 21
biomass is estimated to be 195,6W t@ _4@_ Cohort Biomass
with an ABC of 58,700 L 3-- = Bogoslof --- 18
For the Bogoslof Island area, 2.5- - Donut Hote -15
occasional hydmcousfic surveys welre Aleutian isianas
conducted during February-Mmh to 2--- 1=1 E.Bering Sea
estimate the spawning biomass. Ile
biomass was estimated to be
2.4 million t in 1988, 2.1 million t in
1989, 0.6 million t in 199 1, and
0.8 million t in 1992. The ABC was 0.5 3
estimated to be 169,000 t in 1993.

0 0
77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
Year

Bering Sea/Aleutian Islands Groundfish Resources 13

2. PACIFIC COD

By Grant G. Thompson

In North American waters, Pacific cod (Gadus Tagging studies have demonstrated significant
macrocephalus) are distributed from Santa Monica migration of Pacific cod between the Bering Sea and
Bay, California, through the Gulf of Alaska, Aleu- the Aleutian Islands region. Therefore, the resource
tian Islands, and eastern Bering Sea to Norton is managed as a single unit under the NPFMC'S
Sound. They occur demasally on
the continental shelf and upper Pacif ic Cod
continental slope. They are Eastern Bering Sea
omnivorous. feeders that attain sizes
in excess of 100 cm in length and Catch (1,000 metric tons) Biomass (1.000 metric tons) 1400
20 kg in weighL Ages up to 20
18 years have been observed, Biomass 1200
although young fish (ages 3 to 8) 150- 1000
comprise the bulk of the catch.
Spawning occurs between January 800
and April, perhaps peaking in 100- 600
Mamh. Pacific cod is harvested Cat
using a variety of gear types, 400
including (in order of catch vol- 50 -
umes) trawl, longline, and pot gear. 200
Fishing has historically occurred 0 0
year-round- 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
Year

14 Bering Sea/Aleutian Islands Groundfish Resources

FMP for groundfish of
the Bering Sea and PACIFIC COD
Aleutian Islands Eastern Bering Sea and Aleutian Islands
region. Although
foreign and joint Average catch (1977-92) = 115,000 t
venture flew were Long-term potential yield = 143,000 t
major participants in Acceptable biological catch (1993) = 164,500 t
Age/length at recruitment = 3 yrs/42 cm
the flShUY throughout Age/length at 50% maturity = 5.3 yrs/61 cm
most of the 1980s, Maximum observed age = 18 yrs
growth in the domes- Abundance and trend = Average, declining
tic fleet has altered Stock biomass (age 3+, model projection) = 690,000 t
Harvest strategy = F33,
this picture drarnati- Importance of recreational fishery = Negligible
cally. Ile foreign Management = BSAI Groundfish FMP
fleet has not received Status of exploitation = Fully exploited
an allocadon since Projected spawning stock per recruit = Above maintenance level
1987, and the joint Assessment Method = Age structured
venture fleet has not Fc., = 0.142 F30% = F@rf,"Im = 0.139 F... 0.427 F30% = 0.121
received an anoCafion 0.11 F1112 0.148 M = 0.29
since IM. Pacific
cod catches have
increased substantially from the average level of exceptionally strong year class spawned in 1977.
41,000 t observed from 1977 to 1979. Total landings Good (though not exceptional) year classes were
peaked in 1988 when 198,000 t were taken in the spawned in 1978 and 1982, helping to sustain a high
eastern Bering Sea and Aleutian Islands region. biomass level. Throughout the 1980s, trawl survey
Total landings in 1991 were the second highest on estimates of biomass for the eastern Bering Sea
record, with 176,000 t reported for the two areas. portion of the stock exceeded 900,000 L, peaking in
Without exception, the vast majority of the com- 1987 at 1,142,000 L Model estimates of biomass for
bined-area catches are taken in the eastern Bering this area and period show a similar abundance trend.
Sea. However, back-to-back poor year classes from 1986
Currently, the stock is declining following a and 1987 have led to a pronounced decline from the
period of high abundance that was fueled by an high biomass levels observed during most of the

PACIFIC COD
Eastern Bering Sea and Aleutian Islands
. COMMERCIAL CATCH (1,000 t)

1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

-----------------------------------------------------------------------------------
Eastern Bering Sea
Foreign 39 57 56 40 54 0 0 0 0 0
Joint Venture 10 24 36 58 47 107 44 8 0 0
Domestic 34 29 41 33 42 86 120 155 167 126
Subtotal 83 ill 133 131 143 193 165 163 167 126

Aleutian Islands
Foreign 2 1 1 0 0 0 0 0 0 0
Joint Venture 5 6 6 6 10 3 0 0 0 0
Domestic 3 14 6 4 3 2 4 8 8 38
Subtotal 10 22 13 10 13 5 4 8 8 38

Total 93 133 145 141 157 198 169 171 176 164

Bering Sea/Aleutian Islands Groundfish Resources 15

1980s. The trawl survey biomass estimates for the
eastern Bering Sea portion of the stock in 1990,
1991, and 1992 were only 709,000 L, 533,000 t, and
547,000 t, respectively, with model estimates of
biomass coming in only slightly higher. Although
the stock is declining, this is more likely due to
unusually low recruitment than to excessive fishing.
The MSY for Pacific cod cannot be accurately
estimated; however, historical data suggest the LTPY
to be 143,000.L

For further information

Thompson, G. G. 1992. Pacific cod. la Stock
assessment and fishery evaluation document for
groundfish resources in the Bering Sea/Aleutian
Islands region as projected for 1993, p. 2:1-2:37.
North Pacific Fishery Management Council, P.O.
Box 103136, Anchorage, AK 99510.

Thompson, G. G., and R. G. Bakkikin 1990.
Assessment of the eastern Bering Sea Pacific cod
stock using a catch-at-age model and trawl survey
data. Int. North Pac. Fish. Comm. Bull. 50:215-236.

16 Bering Sea/Aleutian Islands Groundfish Resources

3, YELLOWFIN SOLE

By Thomas K. Wilderbuer

4<7

177

-0i

Photo: AFSC
Yellowfin sole (Pleuronectes asper) inhabits these nearshore waters and gradually shift to deeper
continental shelf waters of the North Pacific Ocean water and, at lengths of 16 to 20 cm (mainly ages 5-
from off British Columbia, Canada, to the Chukchi 8 years), they begin occupying much the same waters
Sea. It is the most abundant flatfish as the larger fish.
in the North Pacific Ocean and by
far the most abundant in the eastern Yellowf in Sole
Bering Sea--the only region in Eastern Bering Sea/ Aleutian Islands
North America where it forms
commercially harvestable concen- 600- Catch (1,000 metric tons) Biomass (1,000 metric tons) 4000
trations.
Yellowfin sole is a small flatfish 500- Survey
attaining a maximum size of about Biomass -3000
40 cm and 700 g; it averages about 400-
26 cm and 200 g in commercial Catch
catches. In summer, yellowfin sole 300- -2000
are found from nearshore areas to Biomass
depths of about 100 m. In winter, 200- SS Mod 1000
concentrations of adults move to 100-
depths between 50 and 200 m to
avoid ice cover. Spawning occurs 0- 0
from June to August in nearshore 54 57 60 63 66 69 72 75 78 81 84 87 90
waters. Young juveniles develop in Year

Bering Sea/Aleutian Islands Groundfish Resources 17

YELLOWIN SOLE
Eastern Bering Sea
COMMERCIAL CATCH (1,000 t)

Category 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
----------------------------------------------------------------------------------------
Domestic 0 0 0 0 0 9.8 1.7 10.9 84.5 106.0
Joint-
venture 22.5 32.8 126.4 151.4 179.6 213.3 151.5 69.7 0 0
Foreign
Japan 64.8 83.9 59.5 49.3 1.1 0 0 0 0 0
U.S.S.R. 0 8.0 8.2 0 0 0 0 0 0 0
ROK 21.0 34.9 33.0 7.6 0.7 0 0 0 0 0
Others 0 0 0 0.2 0 0 0 0 0 0

Total 108.4 159.5 227.1 208.6 181.4 223.2 153.2 80.6 84.5 106.0

FAstern Bering Sea yellowfin sole are from a Cohort analysis and stock synthesis modeling
single stock. Their distribution extends into the indicate that stock abundance during the 1980s was
Aleutian Islands region but only to a limited extent as high, if not higher, than abundance during the
and in minor abundances. early years of the fishery. Surveys have shown
Fisheries for yellowfin sole were initiated by unreasonable biomass fluctuations in the 1980s
Japan in 1954. Japanese and other foreign fisheries ranging from 1.8 to 3.9 million t. Nevertheless,
continued to take yellowfin sole until 1987, after even the lower estimates demonstrate that the
which all of the catch was allocated to U.S. fisheries. abundance of yellowfin sole remains high. The 1992
The species was intensively exploited for fish meal survey estimate was 2.2 million L Results from
during the early years of the fisheries, with catches stock synthesis indicate that biomass was as high as
ranging as high as 553,700 t (in 1961) and averag- 2.8 million t in 1984 and is estimated at 2.6 million t
ing 404,000 t in 1959-62. Catches of this magnitude in 1992.
were more than the stock could sustain and subse-
quently they caused a sharp decline in abundance.
Following a recovery
of stock abundance
during the 1970s, YELLONFIN SOLE
catches have ranged as Eastern Bering Sea
high as 227,100 t (in
1985) and averaged Average catch (1977-92) = 131,793 t
131,793 t from 1977 to Long-term potential yield (MSY) = 155,000-284,000 t
Exploitable biomass (1993) = 2,504,500 t
1992. Catches Acceptable biological catch (1993) = 238,000 t
declined to 106,OW t Fishing strategy F330
in 1992 mainly as a Abundance and trend = High and declining
result of limitations on Status of exploitation = Under-exploited
Importance of recreational fishery = Nonexistent
bycatch of prohibited Management = BSAI Groundfish FMP
species rather than to a Age/length at 50% maturity = Males: 7 years/20.3 cm
decline in abundance. Females: 8 years/23.8 cm
Yellowfin sole has Age/length at 50% recruitment = Males: 9 years/26.1 cm
Females: 9 years/27.1 cm
been mainly utilized Maximum age = 30 years
for human consump- Assessment Method = Age structure model
tion since the early
1960S. M = 0.12 F0.1 = 0.14 FN_ = 0.50 F3.s%= 0.118
F 1977-92 0.061 F-riaim= 0.17

18 Bering Sea/Aleutian Islands Groundfish Resources

I'he primary reason for the recovery of the stock
during the 1970s and early 1980s was the recruit-
ment of a series of stronger than average year classes
spawned in 1968-77. Many of these year classes still
support the population and there is good recruitment
from some later year classes. particularly 1981,
which may be one of the strongest yet observed. and
a good 1983 year class. Abundance of eastern
Bering Sea yellowfin sole is at a high level and
strong incoming year classes should maintain the
stock in good condition.

For further information

T. K. Wilderbuer. 1992. Yellowfin sole. In Stock
assessment and fishery evaluation document for
groundfish resources in the Bering Sea/Aleutian
Islands region as projected for 1993. North Pacific
Fisheries N[anagement Council, PO. Box 103136,
Anchorage, AK 99510.

Bering Sea/Aleutian islands Groundfish Resources 19

4. GREENLAND TURBOT
By Thomas K. WiWerbuer and Terrance M. Sampk

A-
Vd. 2-
"N-T

C"Mi
0.

Greenland turbot (Reinhardtius hippoglossoides) between 63,000 and 78,000 t from 1972 to 1976.
are distributed in the Atlantic and Pacific Oceans. Catches declined in the late 1970s but were still
In the North Pacific, they are most abundant in the relatively high in 1980-83 with annual catches
eastern Bering Sea and Aleutian
Islands region. It is a demersal
flatfish species. Juveniles inhabit Greenland Turbot
the continental shelf waters of the Eastern Bering Sea/ Aleutian Islands
eastern Bering Sea until about 4 or
5 years of age. Older age groups am Catch (1,000 metric tons) Biomass (1.000 metric tons)
found in continental slope waters at 100 1000
depths greater than 200 m.
Ile Greenland turbot is a large -800
flatfish that may live more than
20 years and reach sizes as great as 60- 600
110 cm and 16-17 kg. Spawning SRA Biomass
occurs in winter and may be pro- 40 ---- 400
tracted, starting in September or Catch
October and continuing until March. 20 200
Maturity is reached at 5-10 years.
The fishery for Greenland turbot MMMIP
72 74 7e
intensified in the early 1970s with 70 78 80 82 84 so Be go 92
annual catches reaching a peak of Year

20 BerIng Sea/Aleutian Islands Groundfish Resources

GPJMNLAND TURBOT
Eastern Bering Sea and Aleutian Islands

Average catch (1977-92) = 25,870 t
Long-term potential yield (MSY) = 27,100 t
Exploitable biomass (1992) = 292,500 t
Acceptable biological catch (1992) 7,000 t
Fishing strategy = Bycatch only
Abundance and trend = Low and decreasing
Status of exploitation = Fully exploited
Importance of recreational fishery = Non-existent
Management - BSAI Groundfish FMP
Age/length at 50% maturity = 5-10 years/44-57 cm
Age/length at recruitment = 5 years/44 cm
Maximum age = At least 20 years
Assessment Method = Yield per recruit and
stock reduction analysis

M - 0.18 F0. I = 0.062 Fw = 0.08 F1,2 0.001
F,97.1_92 - 0-051 F@rftt@@ = 0.068

ranging Erom 48,000 to 57,000 L Catches have in 1979, and again in 1981-82, but a notable absence
continued to decline to less than 10,000 t since 1986. of similar-sized fish in later surveys.
For 1992, no directed fishery was allowed and Results of comparative trawling between a U.S.
harvest was bycatch only. This decline is primarily research vessel and Japanese commercial vessels
due to catch restrictions placed on the fishery indicate that the bottom trawl survey of the conti-
because of continuing poor recruitment observed nental slope underestimates the biomass of
since 1986. Greenland turbot. Because of this, stock-reduction
Results from triennial surveys conducted on the analysis has been used to estimate the biomass and
eastern Bering Sea shelf in 1975 and 1979-92 have population trend to evaluate the consequences of
shown a significant decline in the juvenile popula- various levels of fishing mortality. Results of the
tion. In addition, surveys of the continental slope analysis suggest that the biomass of Greenland
indicated strong recruitment of fish less than 55 cm turbot has steadily decreased from virgin levels of
over I million t in 1960 to 292,500 t in 1993.

GREENLAM TUPJ30T
Eastern Bering Sea and Aleutian Islands For further information
COMMERCIAL CATCH (t)
Wilderbuer, T. K and T. M. Sample. 1992.
Year Foreign Joint Domestic Total Greenland turbot. Stock assessment and fishery
Venture evaluation document for groundfish resources in the
------------------------------------------ Bering Sea/Aleutian Islands Region as projected for
1983 47,554 4 0 47,558
1984 23.097 22 0 23,119 1993. North Pacific Fishery Management Council,
1985 14,720 11 0 14,731 RO. Box 103136, Anchorage, AK 995 10.
1986 6.894 36 2,934 9,864
1987 1,048 59 8,479 9,585
1988 0 88 7,020 7,108
1989 0 50 8,772 8,822
1990 0 1 9,618 9,619
1991 0 0 6,119 6,119
1992 0 0 1,641 1,641

Bering Sea/Aleutian Islands Groundfish Resources 21

5. ARROWTOOTH FLOUNDER
By Terance M. Sample and Thomas K. Wilderbuer

Affowtooth flounder (Atheresthes stomias) is fishery. Catches of arrowtooth flounder ranged
widely distributed from California to the Gulf of from 19,000 to 25,000 t during 1974-76. Catches
Alaska, and in the central and northern Bering Sea decreased thereafter to 3,000 t in 1990 and 1991
westward to the Asiatic coast.
Arrowtooth flounder is a relatively
large flatfish species that occupies Arrowtooth Flounder
continental shelf waters almost Eastern Bering Sea/ Aleutian Islands
exclusively until age 4, and at older
ages is found in both shelf and slope 25 Catch (1,000 metric tons) Biomass (1.000 metric tons) 600
waters to depths of 900 in. A
maximum length of 84 cm and ages
of over 15 years have been observed. 20 - 500
Spawning probably occurs from Catch
------ - --- --- 400
December to February in the Bering 15
Sea. 300
Arrowtooth flounder is similar in 10
life history, distribution and exploi- 200
tation to the Greenland turbot. It 5
has been an undesirable commercial 100
species and generally has been taken 0 0
as by catch in other target fisheries, 70 72 74 76 78 80 82 84 86 88 90 92
mainly in the Greenland turbot Year

22 Bering Sea/Aleutian Islands Groundfish Resources

ARROWTOOTH FLOUNDER
Eastern Bering Sea and Aleutian Islands

Average catch (1977-92)' 9,446 t
Long-term potential yield (MSY) = 59,000 t
Exploitable biomass (1992) = 479,700 t
Acceptable biological catch (1993) = 72,000 t
Fishing strategy F35%
Abundance and trend = High and increasing
Status of exploitation = Under-exploited
Importance of recreational fishery = Non-existent
Management = BSAI Groundfish FMP
Age/length at 50% maturity = Unknown
Age/length at recruitment = Male 4 years/29.6 cm
Female 4 years/30.4 cm
Maximum age = At least 20 years
Assessment Method = Yield per recruit

M = 0.20 Fo., =0.18 F,_ = 0.41 Fl,,2 0.018
F1977-92 = 0-05 F-fishim = 0.25 F35% = 0. 15

and were 8,500 t in 1992. This decline is primarily 490,000 t in 1990 and have remained at this level
the result of catch restrictions placed on the through 1992. Trawl surveys conducted in the
Greenland turbot fishery and the phasing out of the Aleutian Islands Region have indicated that the
foreign fishery in the U.S. EEZ. Arrowtooth resource also increased there during the 1980s Erorn
flounder is underutilized as a commercial species. 40,400 t in 1980 to 125,700 t in 1986. A series of
Biomass estimates from bottom trawl surveys on strong year clams accounts for the increase in
the Bering Sea shelf and slope have revealed abundance and should continue to maintain the
moderate increases in arrowtooth flounder abun- overall population abundance at a high level.
dance from 1975 (58,000 t) through 1982 (92,000 t).
Significant increases in total biomass have been
observed since the early 1980s reaching nearly For further information

Sample, T. M., and T. K. Wilderbuer. 1992.
ARROWTOOTH FLOUNDER Arrowtooth flounder. In stock assessment and
Eastern Bering Sea and Aleutian Islands fishery evaluation document for groundfish resources
COMMERCIAL CATCH (t) in the Bering Sea/Aleutian Islands Region as
projected for 1993. North Pacific Fishery Manage-
Year Foreign Joint Domestic Total ment Council, P.O. Box 103136, Anchorage, AK
Venture 99510.

-----------------------------------------
1983 13,880 89 0 13,969
1984 9,184 268 0 9,452
1985 6,851 507 17 7,375
1986 3,462 3,376 65 6f9O3
1987 2,789 1,675 75 4,539
1988 0 2,574 3,309 5,883
1989 0 2,264 958 3,222
1990 0 600 3,572 4,232
1991 0 0 4,069 4,069
1992 0 0 8,516 8,516

Bering Sea/Aleutian Islands Groundfish Resources 23

6. ROCK SOLE

By Thomas K. Wilderbuer and Gary E. Walters

A--

APF

Photo: AFSC
Rock sole (Pleuronectes bqilineatus) is distributed L. bilinewus peracuata (Cope) of the Gulf of Alaska,
from southern California (where it is scarce) Bering and Okhotsk Seas and L. bilineatus
northward to the Bering and Okhotsk Seas and mochigaeri Snyder of the northwestern Pacific
southward to the Korean peninsula
and the Sea of Japan. The largest
concentrations are found on the mid- Rock Sole
Bering Sea shelf, the center of its Eastern Bering Sea/ Aleutian Islands
distribution. Rock sole is a relatively
catch (1,000 metric tons) Biomass (1,000 metric tons)
small flatfish that may attain weights 80 2000
over 1.5 kg and lengths of 53 cm for Survey
males and 60 cm for females. Biomass
Maximum age is at least 25 years. 1500
Spawning occurs during winter and
early spring with 50% sexual SS Biomas
maturity occurring at 29 cm for 40 1000
males and 32-33 cm for females, or Catch
at about 8 years of age. Rock sole is 20 500
one of a few species of flatfish with
demersal eggs.
There are dime subspecies: 0 0
bilineatus bilineata (Ayers) off the 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91
West Coast of North America, Year

24 Bering Sea/Aleutian Islands Groundfish Resources

ROCK SOLZ
Eastern Bering Sea

Average Catch (1977-92) - 22,080 t
Long-term potential yield (MSY) - 136,400-184,000 t
Exploitable biomass (1992) - 1,500,500 t
Acceptable biological catch (1993) - 185,000 t
Fishing strategy F350
Abundance and trend = High and stable
Status of exploitation = Underexploited
Importance of recreational fishery = Non-existent
Management = BSAI Groundfish FMP
Age/length at 50% maturity = Males 8 years/29 cm
Females 8 years/32-33 cm
Age/length at recruitment = Males 3 years/14.4 cm
Females 3 years/14.3 cm
Maximum age = At least 25 years
Assessment Method = Dynamic pool models

M - 0.2 Fo., = 0.159 Fmy = 0.176 F1112 0.003
F1977-92 = 0-029 F@rftsblw 0.176 F351 0-18

Ocean. Commercial catches of rock sole in the level (40,000 t in 1992) primarily due to the bycatch
eastern Bering Sea are managed as a unit stock. of valuable halibut and crab species taken in the
With the advent of the yellowfin sole bottom pursuit of rock sole. Rock sole is currently
trawl fishery in the late 1950s and early 1960s, rock underutilized with a very low fishing mortality rate.
sole catches occurred first as bycatch, but also as a Biomass of rock sole are estimated Erom bottom
target species during the roe-bearing season. trawl surveys, cohort analysis and stock synthesis
Catches peaked at nearly 61,000 t in 1972 and then modeling. Rock sole biomass was relatively stable
declined to low levels until the late 1980s when a from 1975 to 1979, but then increased substantially
valuable domestic rock sole roe fishery developed, throughout the 1980s from 951,000 t in 1979 to
taking over 63,000 t in 1988. Ibis domestic roe 1.5 million t in 1992. Current biomass may be at or
fishery is believed to have been worth $25-35 million above virgin levels.
in 1988. Current catches have remained below this The primary reason for the increase in abundance
during the 1980s appears to be the recruitment of a
ROCK SOLZ series of strong year classes spawned Erom 1981 to
Eastern Bering Sea and Aleutian Islands 1987. Trawl survey estimates of age composition in
COMMERCIAL CATCH (t) 1991 indicated that 84% of the population numbers
were ages 4-8. corresponding to the 1981-87 year
Year Foreign Joint Domestic Total classes. This strong recruitment should provide an
Venture abundant and stable biomass in the near future.

-------------------------------------------
1983 4,478 9,140 0 13,616 For further information
1984 10,156 27,523 0 37,679
1985 6,671 12,079 0 18,750 Wilderbuer, T. K., and G. E. Walters. 1992. Rock
1986 3,394 16,217 0 19,611
1987 776 11,136 14,209 26,121 sole. In Stock assessment and fishery evaluation
1988 0 40,844 22,374 63,218 document for groundfish resources in the Bering
1989 0 21,010 23,544 44,554 Sea/Aleutian Islands Region as projected for 1993.
1990 0 10,492 13,584 24,076 North Pacific Fishery Management Council, P.O.
1991 0 0 26,297 26,297
1992 0 0 39,314 39,314 Box 103136, Anchorage, AK 99510.

Bering Sea/Aleutian Islands Groundfish Resources 25

7. OTHER FLATFISH
By Gary E. Walters and Thomas K. Wilderbuer

The "other flatfish"complex of
species is a category of flatfish created Flathead Sole
for management purposes. This Eastern Bering Sea/ Aleutian Islands
category is made up prunarily of two
species, flathead sole 60 Catch (1.000 metric tons) Biomass (1,000 metric tons) 700
(Hippoglossoides elassodon) and
600
Alaska plaice (Pleuronectes 50
quadrituberculatus), but also includes
500
several others such as rex sole (Errex 40 -----_Survey- Biomas
zachirus), Dover sole (Microstontias 400
pacificus), starry founder (Platichthys 30
stellatus), longhead dab (Pleuronectes 300
20
proboscidea), and butter sole 200
(Pleuronectes isolepis). With the
exception of Alaska plaice and 10 100
flathead sole, these species are not 0 0
abundant in the eastern Bering Sea. 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91
Year

OTHER FISH
Eastern Bering Sea and Aleutian Islands

Flathead Sole Alaska Plaice

Average catch (1982-91) = 5,250 t 22,420 t
Long-term potential yield (MSY) = 65,100 t 76,600 t
Exploitable biomass (1992) = 650,100 t 562,400 t
Acceptable biological catch (1993) = 105,600 t 77,300 t
Fishing strategy = F 356 F 356
Abundance and trend = High and High and
increasing stable
Status of exploitation = Underexploited Underexploited
Importance of recreational fishery = None None
Management = BSAI Groundfish FMP
Age/length at 50% maturity = Unknown Females
9 yrs/31 cm
Age/length at recruitment = 3 yrs/17 cm 4 yrs/13 cm
Maximum age = 20+ years 23+ years
Assessment Method = Yield per recruit
M = 0.2 0.2
F (0.1) = 0.159 0.159
F (MSY) = 0.176 0.176
F (1992) = 0.002 0.003
F (1977-91) = 0.023 0.031
F (overfishing) = 0.23 0.2
F 356 = 0.193 0.167

26 Bering Sea/Aleutian Islands Groundfish Resources

OTHER 17,ATFISH
Eastern Bering Sea and Aleutian Islands
COMMERCIAL CATCH (1,000 t)

Category 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991
---------------------------------------------------------------------------------------
Flathead Sale
Foreign 4.3 4.4 3.6 2.6 0.7 0.2 0 0 0 0
Joint Venture 0.2 0.8 0.9 3.1 4.5 3.7 6.8 3.5 2.2 0
Domestic 0 0 0 0 0 0.01 0 0.02 9.9 1.1

Total 4.5 5.2 4.5 5.7 5.2 3.9 6.8 3.5 12.1 1.1

Alaska Plaice
Foreign 6.6 9.1 15.1 11.3 6.2 0.8 0 0 0 0
Joint Venture 0.2 1.6 3.7 13.6 40.3 17.5 61.7 13.8 15.9 0
Domestic 0 0 0 0 0 0.05 0 0.07 4.8 1.8

Total 6.8 10.7 18.8 24.9 46.5 18.4 61.7 13.9 20.7 1.8

Flathead sole Alaska plaice

Flathead sole range from Point Reyes, California, Alaska plaice range Erom the Gulf of Alaska to
along the U.S. West Coast and British Columbia into the Bering and Chukchi Seas and south into Asian
the Gulf of Alaska, Bering Sea, Aleutian Islands, waters to the Sea of Japan, including the Okhotsk
and the Kuril Islands. It is by far most abundant on Sea to as far south as Peter the Great Bay. In the
the eastern Bering Sea shelf, occurring at bottom eastern Bering Sea, where Alaska plaice is most
depths between 100 and 250 in. Flathead sole is a abundant, it is almost entirely limited to continental
relatively small-sizod flatfish and may attain lengths shelf waters with a distribution similar to yellowfin
up to 49 cm for males and 52 cm for females, and sole. The highest concentrations are found on the
weights of 1.2 to 1.5 kg, respectively. Most females middle shelf area southeast of St. Matthew Island
mature by age 2, but whether or not spawning occurs primarily at depths less than 150 in. Alaska plaice
at this age is unknown. Spawning occurs during the are a relatively large flatfish and may reach a length
spring. of 60 cm and an age of over 20 years. Alaska plaice
Flathead sole are managed by the NPFMC as one spawn Erom April to June on hard, sandy substrates
stock unit in the Bering Sea. It is of limited com- with females reaching 50% maturity at 31 cm, which
mercial importance and are usually caught as corresponds to an age of 9 years.
bycatch in the yellowfin sole and rock sole (roe) Commercial fisheries catch information reported
trawl fisheries. Catches from 1963 to 1980 averaged by foreign fleets during the 1960s indicated that
18,400 t annually with a peak of 5 1,000 t occurring Alaska plaice was not sought after and was lightly
in 197 1. Catches since 1980 have averaged only exploited. Although not a target species, it is
5,070 L Flathead sole are underexploited in the believed that substantial unreported removals of
Bering Sea. Alaska plaice occurred in the intensive yellowfin
Bottom trawl surveys conducted by the NNFS in sole fishery during the 1960s and may have contrib-
the eastern Bering Sea indicate that the flathead sole uted to a population decline. In 1975, when Bering
resource has increased from 100,000 t in 1975 to Sea trawl surveys were initiated, Alaska plaice
over 650,000 t in 1992. This increase appears to be biomass was estimated at 103,500 t@ the lowest level
the result of a series of consecutive strong year observed during the time series. Catches since the
classes spawned in the late 1970s and early 1980s. implementation of the Magnuson FMCMA in 1977

Bering Sea/Aleutian Islands Groundfish Resources 27

have increased to a high of 61,600 t
in 1988 and have averaged only Alaska Plaice
16,800 t (F = 0.032). Alaska Eastern Bering Sea/Aleutian Islands
plaice are currently underexploited.
Bottom trawl surveys indicated 70 Catch (1,000 metric tons) Biomass (1.000 metric tons) 1000
that Alaska plaice biomass increased
from a low of 103,500 t in 1975 to 60
734,400 t in 1994. Since 1984, the 800
biomass has remained stable between 50
525,000 and 600,000 t.The increase 40 600
during the late 1970s to early 1980s 400
was caused by a series of stronger
than average year classes from 1973 20
to 1976. 200
10
For further information 0 0
63 65 67 69 71 73 75 77 79 81 83 85 87 89 91
Walters, G. E., and T. K.Wilderbuer. Year
1992. Other flatfish. In Stock
assessment and fishery evaluation document for
groundfish resources in the Bering Sea/Aleutian
Islands Region as projected for 1993. North Pacific
Fishery Management Council, P.O. Box 103136,
Anchorage, AK 99510.

28 Bering Sea/Aleutian Islands Groundfish Resources

8. PACIFIC OCEAN PERCH

By Daniel H. Ito and James N. lanelU

SIC V)

Pacific ocean perch (Sebastes alutus) inhabit the divided into three subgroups: 1) Pacific ocean
outer continental shelf and upper slope regions of the perch, 2) shortraker and rougheye rockfishes, and
North Pacific Ocean and Bering Sea regions. TWo 3) sharpchin and northern rockfish. These
main stocks of Pacific ocean perch have been subgroups were established by the NPFMC to
identified in the region--an eastern
Bering Sea slope stock and an Pacific Ocean Perch
Aleutian Islands stock. Eastern Bering Sea
For management purposes, four Catch (1.000 metric tons) Biomass (1.000 metric tons)
other associated species of rockfish 50- 80
(northern rockfish, S. polyspinis;
rougheye rockfish, S. aleutianus; 40 -
shortraker rockfish, S. borealis; and 60
sharpchin rockfish, S. zacentrus) are 30- mass
managed as a part of the Pacific catch
ocean perch complex. For the
eastern Bering Sea slope region, the 20 - --
POP complex was divided into two 20
subgroups: 1) Pacific ocean perch 10_
and 2) shortraker, rougheye,
sharpchin, and northern rockfishes 0-1 015MMM M'PM9P9Pp PM,L0
combined. For the Aleutian Islands 1960 1965 1970 1975 1980 1985 1990
region, the POP complex was Year

Bering Sea/Aleutian Islands Groundfish Resources 29

PACIFIC OCZAN PZRCR
Eastern Bering Sea and Aleutian Islands
COMMERCIAL CATCH (t)

r.@ctArn Rtgring _qa&L@ @ Aleutian Tqlandn

Year Foreign JV DAP Total Foreign JV DAP Total
--------------------------------------------------------------------------

1983 116 97 8 221 272 8 280
1984 156 134 1,279 1,569 356 273 2 631
1985 35 32 717 784 Tr 215 93 308
1986 16 117 427 560 Tr 160 126 286
1987 5 50 875 930 0 500 504 1,004
1988 0 51 996 1,047 0 1,513 466 1,979
1989 0 31 1,986 2,017 0 0 2,706 2,706
1990 0 0 5,639 5,639 0 0 14,650 l4f650
1991 0 0 4fO83 4,083 0 0 4,000 4,000
1992 0 0 3f540 3,540 0 0 11,700 11,700

JV = Joint Venture DAP = Domestic Annual Processing

protect individual low catch-quota species from ties generally occurring between 100 and 400 m.
possible overfishing. Pacific ocean perch are slow-growing and long-
Of the five species which comprised the Pacific lived. Longevity has been estimated at 90 years.
ocean perch complex, S. alutus has historically been The natural mortality rate equals 0.05. This species
the most abundant and has contributed most to the begins to recruit to the commercial fishery at about
commercial rockfish catch. Furthermore, the bulk of age 5 and is fully recruited by age 10, corresponding
the research on
rockfish has concen-
trated on Pacific PACIFIC OCEAN PZRCH
ocean perch; little Eastern Bering Sea and Aleutian Islands
biological or
assessment ifforma- Average Catch: Eastern Bering Sea (EBS) - 1,883 t
tion is available for (1977-92) Aleutian Islands (AI) - 4,108 t
Long-term potential yield: EBS - 4f6OO t
the other species. AI - 10,300 t
Consequently, this Acceptable biological catch (1993): EBS = 3,300 t
synopsis deals AI - 13,870 t
primarily with Exploitable biomass (1993): EBS - 59,700 t
AI - 260f3OO t
Pacific ocean perch. Fishing strategy , F3s%
Pacific ocean Age at recruitment - 5-10 years
perch am usually Length at recruitment = 26-32 cm
associated with Maximum age - 90 years
Abundance and trend - Moderate and increasing
trawlable cobble Importance of recreational fishery - None
submate. A Management - BSAI Groundfish FMP
demersal species, it Status of exploitation - Fully exploited
can be found at M = 0.05 Fo.@ = 0.06 FWY 0.06
depths ranging from F@rf"U" = unknown F1977_92&wr&g* = <0*06
50 to 700 in, with
commercial quanti-

30 Bering Sea/Aleutian Islands Groundfish Resources

with fork lengths of about 26 and Pacific Ocean Perch
32 an, respectively. Although the Aleutian Islands
maximum recorded length is 54 cm,
the bulk of the commercial catch is Catch (1,000 metric tons) Biomass (1,000 metric tons)
comprised of individuals ranging from 120-- 400
25 to 45 cm. Females are viviparous, 100- -
retaining eggs in the ovary after -Catch-
fertilization until the yolk sac is 80--
absorbed. Mating takes place in late
Eall or early winter, with subsequent ___200
Larval extrusion occurring in late
winter or early spring. 40---
Very little biological information is
available for the four other species 20-
within the POP complex. Preliminary
information suggests, however, that 0- -0
they are also slow-growing and long- 1960 1965 1970 1975 1980 1985 1990
lived. Maximum reported ages for I Year
rougheye and shortraker rockfish are
140 and 120 years, respectively. Natural mortality is more than 90-95% from those of the early 1960s,
probably about 0.05 or less, suggesting very low suggesting a depressed stock condition. Since then,
rates of productivity. the stocks have shown signs of rebuilding.
Pacific ocean perch were highly sought after by Based on results from comprehensive age-
Japanese and Soviet fisheries and supported a major structured modeling (stock synthesis), the current
trawl fishery throughout the 1960s and early 1970s. (1993) estimate of exploitable biomass for Pacific
Catches in the eastern Bering Sea peaked at 47,000 t ocean perch is 59,700 t for the eastern Bering Sea
in 1961; the peak catch in the Aleutian Islands stock and 260,300 t for the Aleutian Islands stock.
region occurred in 1965 at 109,100 L Soon after, the The stock in the eastern Bering Sea appears to have
catches declined rapidly. With such long life spans stabilized, whereas, the Aleut= Islands stock
and low rates of natural mortality and growth, appears to be increasing in abundance. The most
Pacific ocean perch were apparently unable to recent estimates of exploitable biomass for the other
sustain such Large removals from their populations. four species in the complex are 29,700 t in the
With the implementation of the MFCMA in eastern Bering Sea and 139,500 t in the Aleutian
1977, the foreign fisheries were gradually phased Islands. In both regions, recent analyses have
ouL Coincident with this reduction in foreign concluded that the recruitment of Pacific ocean
fishing, a significant domestic rockfish fishery perch is highly variable.
developed. The domestic fishery started out as joint
ventures with foreign companies in the mid- 1980s
and has now become a totally domestic industry. For further information
The domestic fishery is primarily composed of
factory trawlers that harvest and process the fish at lanelli, J.N., and D.H. Ito. 1992. Pacific ocean
sea. Although Pacific ocean perch has been the perch. In Stock assessment and fishery evaluation
primary target of the rockfish fishery, recent fisheries document for groundfish resources of the Bering
also target on shortraker and rougheye rockfish. Sea/Aleutian Islands region as projected for 1993.
These species are larger than Pacific ocean perch North Pacific Fishery Management Council, P.O.
and inhabit deeper waters (>300 m) of the continen- Box 103136, Anchorage, AK 99510.
tal slope.
Stock assessments based on catch-per-unit-effort
(CPUE) data from Japanese trawlers indicate that
stock abundance declined to very low levels in all
regions. By 1977, CPUE values had dropped by

Bering Sea/Aleutian Islands Groundfish Resources 31

OTHER ROCKFISH

By Dankl H. 1W

'Me category "other rockfish", Other Rockf ish
includes Sebastolobus SM. and a Eastern Bering Sea
species of Sebastes other thari the
Pacific ocean perch complex. For 3000 Catch (metric tons) Biomass (1,000 metric tons)
management purposes, the other
rockfhsh resource is assumed to 2500- - 10
consist of two separate groups: the
eastern Bering Sea group and the 2000- Catch Biomass
Aleutian Islands group. Informa-
tion on biological parameters is 1500-
lacking for these groups of rock-
fishes. 1000- - 4
Since implementation of the
NFCMA, the peak catch (2,600 t) 500- -2
of other rockfish in the eastern ,
Bering Sea occurred in 1978. In 0 E, 0
the Aleutian Islands region, the 1977 1979 1981 1983 1985 1987 1989 19 91 1993
peak removal occurred I yew later Year
in 1979 with a harvest of about
4,500 L Catches in recent years have been minor biomass. The best estimate of current exploitable
and are mainly incidental to other directed fisheries. biomass for other rockfish is about 8,000 t for the
Ile average catch during 1977-91 amounted to eastern Bering Sea stock and 18,500 t for the
about 560 t from the eastern Bering Sea region and Aleutian Islands stock. The estimates, however,
1,000 t from the Aleut= Islands region. have very wide confidence intervals.
Cooperative U.S.-Japan trawl surveys conducted Information is not available to estimate MSY.
from 1979 to 1988 provided the estimates of absolute However, if one assurnes that the exploitation and

OTEZR ROCKFISH
Eastern Bering Sea and Aleutian Islands
COMMERCIAL CATCH (t)

Alpiitfan Tnlandq

Year Foreign JV DAP Total Foreign JVP DAP Total

1983 212 8 -- 220 1,041 4 1,045
1984 121 8 47 176 42 14 -- 56
1985 33 3 56 92 2 14 83 99
1986 4 12 86 102 Tr 15 154 169
1987 3 4 467 474 0 6 141 147
1988 0 8 333 341 0 68 210 278
1989 0 4 188 192 0 0 481 481
1990 0 0 384 384 0 0 864 864
1991 0 0 328 328 0 0 541 541
1992 0 0 376 376 0 0 699 699

JVP Joint venture DAP Domestic annual processing
i
Catch

32 Bering Sea/Aleutian Islands Groundfish Resources

productivity patterns for other rockfish Other Rockfish
are similar to those of S. alutus, LTPY
has beeen estimated at about 400 t for Aleutian Islands
the eastern Bering Sea and 900 t for 5 Catch (1,000 metric tons) Biomass (1,000 metric tons) 25
the Aleutian Islands region.
It is assumed that the same
exploitation rate used to estimate the 4 Biomass 20
ABC for Pacific ocean perch (S.
alutus) is applicable for estimating 3 15
ABC for other rockfish. Multiplying
M equals 0.05 by the current exploit- Catch
able biomass, yields ABC values of 2 10
400 t for the eastern Bering Sea stock
and 925 t for the Aleutian Islands 1 -5
stock.

1977 1979 1981 1983 1985 1987 1989 1991 1993
Year

For further information

Ito, D.H. 1992. Other rockfish. In Stock assess-
ment and fishery evaluation document for groundfish
resources of the Bering Sea/Aleutian Islands region
as projected for 1993. North Pacific Fishery Man-
agement Council, P.O. Box 103136, Anchorage, AK
99510.

OTHM ROCKFISH
Eastern Bering Sea (EBS) and Aleutian Islands (AI)

Average catch: Eastern Bering Sea (EBS) 550 t
(1977-92) Aleutian Islands (AI) 980 t
Long-term potential yield: EBS 400 t
AI 900 t
Acceptable biological catch (1993): EBS 400 t
AI 925 t
Exploitable biomass (1993): EBS = 8,000 t
Al = 18,500 t
Fishing strategy = F = M
Age/length at recruitment = Unknown/unknown
Maximum age = Unknown
Abundance and trend = Unknown
Importance of recreational fishery = None
Management = BSAI Groundfish FMP
Status of exploitation = Unknown

M = Unknown F0.1 = Unknown Fmr = Unknown
F_f,hi'n = Unknown F1977_92 awrag. = Unknown

Bering Sea/Aleutian Islands Groundfish Resources 33

10. ATKA MACKEREL

By Sandra A. La we

Photo: AFSC
Atka mackerel Pleurogranunus monopterygius is Atka mackerel of the Gulf of Alaskyk and the
a semidemersal species. The species is found from Aleutian Islands region are thought to belong to
the east coast of the Kamchatka Peninsula, through- separate stocks. Commercial fisheries for Atka
out the Komandorskiye and Aleutian Islands, north mackerel in the Bering Sea/Aleutian Islands region
to the Pribilof Islands in the eastern
Bering Sea, and eastward through Atka Mackerel
the Gulf of Alaska to Southeast Eastern Bering Sea/Aleutian Islands
Alaska. Its center of abundance is
in the Aleutian Islands. Aft 50 Catch (1,000 Metric tOnS)
mackerel range from the lower
inteWdal area to depths of 575 m.
but over 95% of their occurrences
have been at depths less than 300 30
m. Both sexes mature at 3-4 years
of age at a size of 31-33 cm. Atka
mackerel commonly attain sizes up 20
to 45 cm and 1. 1 kg in weight. The
maximum age is 14 years, although 10
the bulk of the catch has consisted
of fish 3-7 years old. Spawning 0 @6 88 90 92
generally occurs during June- 78 80 82 84
September at depths of 5-30 m. Year
1

34 Bering Sea/Aleutian Islands Groundfish Resources

ATKIL XACKEREL
Eastern Bering Sea and Aleutian Islands

Average catch (1978-92) 25,900 t
Long-term potential yield (MSY) Unknown
Acceptable biological catch (1993) 117floo t
Age/length at recruitment 3 years/30 cm
Maximum observed age 14 years
Abundance and trend High, stable
Exploitable biomass High
Harvest strategy F = M
Importance of recreational fishery = None
Management = BSAI Groundfish FMP
Assessment Method = Age structured
Status of exploitation = Underexploited

M = 0.30 FO., = 0.324 FN2Y = Unknown

F-rfishim = 0.506 F1077-02 aw @ 0,027

are managed under the NPFMC's Bering Sea- exploitable biomass for 1993 of approximately
Aleutian Islands groundfish FNT. In the Gulf of 1.2 million t. In addition, it predicts good recruit-
Alaska, Atka mackerel are less abundant and are ment from the 1988 and 1989 year classes in order to
included within the "other species" category for produce the level of biomass seen in the 1991 survey.
management under the Gulf of Alaska groundfish Length frequency and age composition data from the
FMP. This species is not an important recreational 1991 survey corroborated the presence of a strong
species. 1988 year class; however, this year class was not yet
Until 1980, Atka mackerel was harvested by apparent in the commercial fishery. Good recruit-
foreign fisheries. U.S. joint venture fisheries then ment combined with low levels of exploitation
dominated the catches from 1982 to 1988. Since indicate that the stock is in good shape and at a high
then, the fishery has become exclusively domestic. abundance level.
From 1979 to 1982 catches declined gradually An estimate of a stock-recruitment relationship is
(23,300 t to 19,900 t), then dropped sharply to required to calculate MSY and its corresponding
11,700 t in 1983. The decline was due to changes in fishing mortality rate U@@. Although there is
the target species and allocation issues rather than recruitment information for Atka mackerel, a stock-
changes in stock abundance. From 1984 to 1987, recruitment relationship could not be inferred from
catches were at record high levels, averaging the data. MSY is therefore unknown. As an
34,000 t annually. A strong 1977 year class, which alternative to F a yield-per-recruit model was used
recruited to the fishery in 1980, supported e fishery level. The F.., level was
th to deterinine; the 0.,
throughout the 1980s. The commercial fisheries can determined to equal 0.324. Another study found that
occur year-round, but the peak of the fishery has when uncertainty is directly incorporated into the
generally been from April to August. In 1992, Atka estimation of stock abundance and recruitment, the
mackerel landings totaled 46,400 t and had an ex- optimal fishing mortality rates would be less than
vessel value of $12.8 million. those derived from deterministic models for sustain-
Atka mackerel occur in large, localized concen- able yield (e.g., FO.). A lower harvest rate of 30%
trations making them an especially difficult species (F = M) was therefore recommended and multiplied
to survey with trawls. They are also difficult to by exploitable biomass to obtain an ABC of 351,300
survey with hydroacoustic gear because they are poor L Because of uncertainties in the estimation of
acoustic targets. Because of survey difficulties, a biomass, the NPFMC decided to step up the use of
stock synthesis model was used to assess the status of the available ABC in 6 equal increments (58,550 t),
Atka mackerel. The model projected a high level of beginning with the 1992 fishery. Thus, the ABC for

Bering Sea/Aleutian Islands Groundfish Resources 35

the 1993 fishery was ATKA NZCKEREL
117,100 L The fishing Eastern Bering Sea and Aleutian Islands
mortality associated with a COMMERCIAL CATCH (t)
catch of 117, 100 t is 0.073;
well below the overfishing
level. The overfishing level Year Foreign Joint Domestic Total
Venture
is defined as the fishing -------------------------------------------------------------
mortality rate that results in 1983 1,214 10,512 0 11,726
the biomass-pa-recruit ratio 1984 112 35,943 0 36,055
falling to 30% of its pristine 1985 1 37,859 0 37,860
1986 6 31,984 0 31,990
level. This rate has been 1987 0 30,061 0 30,061
determined to be F = 0.50( ) 1988 0 19,620 2,465 22,084
and is associated with a 1989 0 56 17,938, 17,994
harvest level of 771,100 L 1990 0 0 22,205 22,205
1991 0 0 22,840 22,840
The ABC of 117, 100 t is 1992 0 0 46,226 46,226
based on an analysis for the
entire Aleutian region. The
bulk of the fishery occurs in
the eastern Aleutian Islands region, whereas the bulk
of the biomass has been found in the western region,
particularly the southwest region. To avoid localized
depletion of the resource, the catch should be
apportioned throughout its range according to the
distribution of biomass. Because of administrative
inability to apportion catches in the Aleutian
management district at this time, the 1993 TAC for
the entire Aleutian Islands region was set at only
32,000 t, an amount appropriate only for the eastern
portion of the Aleutian Islands region where most of
the fishing occurs. An amendment to the FMP has
already been submitted to divide the Aleutians into
three subareas so that catch quotas can be assigned
to spread out the fishing effort in future years.

For further information

Lowe, S. A. 1992. Atka mackerel. In Stock
assessment and fishery evaluation document for
groundfish resources in the Bering Sea/Aleutian
Islands region as projected for 1993. North Pacific
Fishery Management Council, P.O. Box 103136,
Anchorage, AK 99510.

Methot@ R. D. 1990.. Synthesis model: An adaptable
framework for analysis of diverse stock assessment
data. INPFC Bull. 50:259-277.

36 Bering Sea/Aleutian Islands Groundfish Resources

11. SQUID AND OTHER SPECIES

By Loh-Lee Low

-71 V

N
1k.
Ak
/All Ir 1 7 T 'f 'a a- -V t r V7 V 11 11 V

Photo: AFSC
Squid Squid were ocassionally targeted by foreign
fisheries in the paSt. During these periods, catches
Two species of squid are harvested: the red squid peaked at 9,000 t in 1978. Following 1985, as
(Berryteuthis magister) in the eastern Bering Sea, foreign fisheries got phased out of the U.S. EEZ and
and the boreal clubhook squid
(Onychoteuthis borealijaponicus) in OTHER SPECIES
the Aleutian Islands region. Both Eastern Bering Sea/ Aleutian Islands
species am distributed across the
North Pacific Ocean from Asia to Catch (1.000 metric tons) Biomass (1,ooo metric tons)
North America. The red squid is 140--
more northerly distributed, being 120---
found throughout the Bering Sea 800
north to the Bering StraiL The 100----
northward distribution of the boreal S U tvle 600
clubhook squid is limited to the 80
southern Bering Sea. Both species 60-
inhabit pelagic waters. -400
The life span of the two species is 40 ----Catch
about a year. The red squid reaches a . . .
maximum mantle length of 25 cm; 20
the boreal clubhook squid reaches a 0 0
maximum mantle length of 37 cm in 65 70 75 so 85 90
females and 30 cm in males. Year

Bering Sea/Aleutian Islands Groundfish Resources 3

replaced by U.S. fisheries, catches of squids dropped sgu= and OMMR SPXCXZB
to a few hundred tons annually, mainly as incidental Eastern Bering Sea and Aleutian Islands
catches. COMMERCIAL CATCH
Assessment data for squid are not available
bemuse little research has bm di=ted to iL The Year Foreign joint-venture Domestic Total
-------- ---------------------------------
squid resource is believed to be large because of its SQUID (in t)
low position in the trophic chain and light degree of 1983 3,970 10 0 3,980
exploitation. MSY and ABC for squid are unknown 1984 3,133 34 0 3,167
but am believed to be at least equal to the highest 1985 1,588 32 0 1,620
19:6 830 38 0 868
catch on record (10,000 t). 19 7 96 35 1 132
1988 0 171 246 417
Other Species 1989 0 107 199 306
1990 0 0 626 626
1991 0 0 632 632
The "other species" category covers species that 1992 0 0 544 544
are currently of little economic value and not OTHER SPECIES (in t)
targeted upon but have potential economic value or 1983 14,255 1,578 3,307 19,140
are important components of the ecosystern. The 1984 7,533 2,645 10,178
taxonomic groups are sculpins (Couidae), skates 1985 6,283 6,343 927 13,553
(Rajidw), smelts (0smeridae), sharks (Squalidae) 1986 4,044 7,557 379 11,980
1987 2,673 6,121 930 9,724
and octopus (Octopodidae). There were 38 species 1988 0 11,840 803 12,643
of sculpins identified in the Bering Sea/Aleutian 1989 0 4,696 405 5,101
1990 0 0 20,808 20,808
Islands region. At least five species of skates, dM 1991 0 0 17,199 17,199
species of sharks, thm species of smelts, and two 1992 0 0 22,154 22,154
species of octopus am found in this region.
Catches of "other species" increased during the
1960s and early 1970s reaching a peak of 133,000 t well below its biological productivity. Based on
in 1972. Catches declined to a low of 5,000 t in average catches, MSY and ABC are both estimated
1989 as domestic fisheries displaced foreign and at 62,900 L Ile NPFMC has set its ABC at 27,200 t
joint-venture fisheries. Catches have since stabilized for 1992 and 26,600 t for 1993 to accomodate
at 17,000 - 22,000 t during 1990-92. expected catches by the fisheries.
Stock assessments of the "other species" category
are based on trawl survey data. The data show that For further information
the main species taken by bottom trawls are sculpins
and skates. These two groups comprise 95-99% of Bakkqlq R. G. 199 1. Squid and other species, p. 3 1-
the total biomass of the "other species" category 32. In Loh-Lee Low [ed.]. Status of living marine
since 1981. Some other species, however, are resources off Alaska as assessed in 1991. U.S. Dep.
believed to be poorly sampled by bottom trawls, Commer., NOAA Tech. Memo. NUFS-F/NWC-211.
particularly those distributed
inshore and in the pelagic zone. OTHER SPECIES
Surveys indicate that sculpins Eastern Bering Sea and Aleutian Islands
were the largest component of the
category until 1986, when skate Average catch (1977-92) 27,200 t
biomass increased and exceeded Long-term potential yield (MSY) 62,900 t
that of sculpins. The increase Exploitable biomass (1993) 780,000 t
resulted in higher total biomass Acceptable biological catch (1993) 26,600 t
for the "other species" category: Fishing strategy F - M
from 345,OW-460,OW t in 1979- Abundance and trend = High and increasing
status of exploitation = Underexploited
81 to 632,000-827,OW t in 1988- Importance of recreational fishery = None
90. Management = BSAI Groundfish FMP
Ile condition of the resource Assessment Method = Survey biomass
appears good and exploitation is

38 Bering Sea/Aleutian Islands Groundfish Resources

12. WALLEYE POLLOCK

By Anne D. HoHowed

PV
A

up-

PhotD: AFSC
Walleye pollock (Theragra chalcogramma) is a pollock are found primarily in the NPFMC's central
semidemersal schooling fish that is widely distrib- and western regulatory areas (long. 147o-l7OoW).
uted throughout North Pacific temperate and Pollock from these regions are managed as a unit
;subarctic waters. Pollock consume a wide variety of stock because they are considered separate from
prey in the Gulf of Alaska. In 1990,
euphausiids, shrimp, and capelin Walleye Pollock
(Mallotus villosus) were the Gulf of Alaska
principal prey items (by weight) Catch (1,000 metric to'ns) Biomass (1,000 metric tons)
consumed by pollock during the 350- 5000
Summer months. Pollock can attain
lengths of 80 cm; however, the
-4000
majority of mature pollock range 250---
between 40 and 65 cm in length. Blom&
'Me maximum age recorded for 200-- -3000
Gulf of Alaska pollock is in excess
150--
of 18 years, although most pollock -2000
me less than I I years old. Sexual 100-
maturity is attained between ages 3 -1000
L:->- VU

ito 6; spawning occurs during the so-
-winter and early spring. 0 1 -0
In the Gulf of Alaska, major 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993
exploitable concentrations of I Year

,Gulf of Alaska Groundfish Resources 39

those in the Bering Sea, NALLEYE POLLOCK
the Aleutian Islands Gulf of Alaska
region, and the eastern CATCH (1,000 t)
Gulf of Alaska.
Shelikof Strait is a
major pollock spawning Year Foreign JVP DAP Total
------------------------------------------------------------------
am in the Gulf of
Alaska, although other 1983 81.4 134.1 0.1 215.6
spawning locations in 1984 99.3 207.1 0.3 306.7
the western and central 1985 31.6 237.9 15.4 284.9
1986 0.1 62.6 21.3 84.0
areas have been identi- 1987 0.0 22.8 39.2 62.0
fied from the occurrence 1988 0.0 0.2 55.8 56.0
of eggs and larvae as 1989 0.0 0.0 72.5 72.5
well as observations of 1990 0.0 0.0 77.8 77.8
1991 0.0 0.0 83.3 83.3
spawning fish. In 1992 0.0 0.0 83.2 83.2
previous years, these
areas were judged to be
of minor importance
relative to the Shelikof Strait spawning area. surveys of Shelikof Strait, and commercial fisheries.
Triennial bottom trawl surveys of the Gulf of Age structures were collected from fish by port
Alaska and annual hydroacoustic surveys of Shelikof samplers and domestic observers. Age-composition
Strait during the spawning period (March) are estimates indicate that the 1984, 1985, and 1988
conducted by the AFSC. Biomass estimates based year classes were predominant in 1992.
on bottom trawl surveys show a stable biomass trend, The stock-synthesis model was used to assess the
whereas hydroacoustic surveys show a sharp decline. status of the Gulf of Alaska pollock stock in 1992.
The 1990 biomass estimate from the summer bottom This model combines the analysis of catch, abun-
trawl survey was 766,948 t for the western and dance, and age-composition data. The fisheries data
central regulatory areas combined. The 1990 set used in the analysis consisted of estimates of total
hydroacoustic survey assessed the pollock biomass in catch biomass and the age composition of the catch
Shelikof Strait and areas throughout the Gulf of aggregated over all seasons, nations, vessel classes,
Alaska from Prince William Sound to Davidson and statistical areas for years 1976-92. Fishery-
Bank. Most of the survey effort outside Shelikof independent data sets were incorporated into the
Strait was concentrated between the 100 and stock-assessment procedure to help calibrate the
500 fathom contours. The 1990 hydroacoustic resulting abundance estimates to the appropriate
biomass estimate for Shelikof Strait was 381,594 L population level.
The hydroacoustic estimate of the biomass outside of A simulation model was constructed to evaluate
Shelikof Strait excluding Prince William Sound, was the long-term impact of various harvest strategies on
102,271 L A biomass estimate for Prince William Gulf of Alaska pollock. This model incorporated
Sound was not available. Hydroacoustic surveys of process error in our knowledge of the spawner-
Shelikof Strait show an increase in spawning recruit relationship and measurement errors in our
biomass from 382,397 t in 1991 to 580,000 t in ability to assess the stock. An objective function was
1992. developed for the model that balanced increased
The entire pollock TAC in the Gulf of Alaska has yield against the risk of the spawner stock biomass
been allocated to domestic fisheries since 1988. The falling below a threshold level set at 20% of the
1991 and 1992 pollock quotas allocated for the pristine spawner stock biomass. Two recruitment
western and central regions were 100,000 t and scenarios were evaluated. The long-term expected
84,000 t, respectively. In 199 1, the TAC was divided yield under a conservative recruitment scenario was
into four equal quarterly allocations for each of the 169,000 L
NPFMC regulatory areas. Projections of 'Gulf of Alaska pollock biomass
Recent information on the age composition of the and yield have been made for fish age 3 and older for
Gulf of Alaska pollock stock was available from the the period 1993-95. When fishing mortality is at the
bottom trawl surveys, the spring hydroacoustic optimal level, and conservative assumptions regard-

40 Gulf of Alaska Groundfish Resources

ing recruitment
were used, the 1993 POLLOCK
yield would be Gulf of Alaska
203,OW t for the
western and central Average catch (1977-92) = 129,900 t
regulatory arm. Long-term potential yield = 169,000 t
Acceptable biological catch (1993) = 160,000 t
'Me NPFMC set the Exploitable biomass (1993) = 1,087,000 t
TAC (I I LOW t) Harvesting strategy = F = 0.15
and ABC Age/length at recruitment = 3 yrs/30 cm
(157,OW t) well Age/length at 50% maturity = 4-5 yrs/39-45 cm
Maximum age = 18+ yrs
below 203,WO L Abundance and trend = Low and stable
An additional 3,400 Importance of recreational fishery = Minor
t was allocated for Management = GOA Groundfisb FMP
the eastern regula- Assessment Method = Stock synthesis
toryarea. Status of exploitation = Below overfishing level
The overfishing M - 0.30 F1,9, 0. 15 F-erfi.hing = 0.30
level for pollock in F0.1 = 0.28 F33% 0.25 Fogy 0.28
the Gulf of Alaska
was based on the
F,,. The 1993
overfishing level was 286,000 t for the western and
central areas combined. The overfishing harvest
level for the eastern regulatory area was 7,880 L

For further information

Hollowed, A. B., and B. A. Megrey. 1990. Walleye
pollock. In Stock assessment and fishery evaluation
document for the 1991 Gulf of Alaska groundfish
fishery, p. 22-89. North Pacific Fishery Nfanage-
ment Council, P.O. Box 103136, Anchorage, AK
99510.

Gulf of Alaska Groundfish Resources 41

13. PACIFIC COD

By HaroN H. Zenger, Jr.

Pacific cod (Gadus
nwcrocephalus) occur on the Pacific Cod
continental shelf and upper slope Gulf of Alas@a
along the coasts of the United States Catch (metric tons) Biomass (1,000 metric tons) -600
and Cana& north of lat. 340N and 100
throughout the Gulf of Alaska,
Aleutian Islands, and eastern -400
Bering Sea to Norton Sound. 60------- -300
Pacific cod tend to migrate long
distances, resulting in an intermix- 40 -200
ing of the stocks between some 20 -100
regions. Thus the stocks from the
Gulf of Alaska, Bering Sea, and 0 9-77RII -0
Aleutian Islands regions am 77 79 81 83 85 87 89 91
genetically indistinguishable. For Year
management purposes, the stocks Foreign joint venture
am managed as two seperate units E2 Domestic survey Biomass
according to their major areas of I
concentration - the Gulf of Alaska
and Bering Sea-Aleutiazi Islands region. During the phase of foreign fishing in the 1970s
Gulf of Alaska Pacific cod feed on a wide variety to the mid- 1980s, the Pacific cod fishery was
of crustaceans and fish and rarely reach 95 cm in dominated by Japanese longline operations. The
length or 7 kg in weight. Maximum age of cod in foreign catch peaked in 1981 at 35,000 t and ended
this area is 15 years, but accurate ageing of the older in 1987. There was also a relatively small joint
fish is difficult. Sexual maturity is reached at about venture fishery operating at that time; it peaked in
age 5. Spawning occurs during late winter and early 1984 and ended after 1988.
spring.
Ile total Pacific cod catch in
the Gulf of Alaskii was 74,000 t in PACIFIC COD
1992, down 8% from 81,000 t in Gulf of Alaska
199 1. Trawlers caught 68% of the
total 1991 cod landings; longline Average catch (1977-92) =34,450 t
and pot fisheries landed 23% and Long-term potential yield (MSY) =Unknown
9%, respectively. Ex-vessel value Acceptable biological catch (1993) =56,700 t
of the catch was $38A million in Exploitable biomass (1993) =387,700 t
1992, down 8% from Harvesting strategy =FO.1
Age/length at recruitment =3 yrs/45 cm
$41.7 million in 199 1. Catches by Age/length at 50* maturity =5 yrs/60 cm
recreational fisheries am insignifi- Maximum age =15+ years
canL The catch reached a Assessment Method =Age-structured Model
historical high proportion of Importance of recreational fishery =Insignificant
Management =GOA Groundfish FMP
groundfish landings in 1991 when Status of exploitation =Fully exploited
it comprised 35% of all Gulf of Abundance and trend =Moderate & declining
Alaska groundfish landings. In M = 0.29 F0.1 = 0.18 FK5Y = F_flhj@w = 0.18
1992, however, the composition F_ = 0.32 E29$6-92.--g. 0*096
dropped to 28% of total ground-
fish landings.

42 Gulf of Alaska Groundfish Resources

The assessement of
the stocks is based mainly PACIFIC COD
Gulf of Alaska
on trawl survey infozma- COMMERCIAL CATCH (t)
tion. The surveys were
conducted by the NMFS Year Forei'gn JV Domestic Total
every third year, that is ------------------------------------------------------------------
1994, 1987, and 1990. 1983 29,777 2,416 4,198 36,401
Estimates of exploitable 1984 15,896 4,649 3,231 23,776
biomass (cod older than 1985 9,086 2,266 2,954 14,306
age 3) from these surveys 1986 15,211 1,357 8,045 24,612
1987 0 1,978 29,454 31,432
were 570,OW t in 1984, 1988 0 1,661 30,896 32,557
559,000 t in 1987, and 1989 0 0 41,676 41,676
390,000 t in 1990. The 1990 0 0 74,647 74,647
higher biomass in the 1991 0 0 80,974 80,974
1980s was due to the 1992 0 0 74,426 74,426
presence of the exception- I
ally large 1977 year class.
Since then, year classes have been considerably
weaker. With continued full fishing pressure and
weaker recruitment in recent years, the resource is
expected to continue to decline.

For further information

Zenger, H. H., and G. G. Thompson. 1992. Pacific
cod la Stock assessment and fishery evaluation
report for the 1993 Gulf of Alaska groundfish
fishery. North Pacific Fishery Management Council,
PO. Box 103136, Anchorage, AK 99510.

Gulf of Alaska Groundfish Resources 43

14. FLATFISH

By Titomas K. WiNerbuer and Eric S. Brown

_7
-,a VON%

_4
-tv
7-

F
R

'N W;AT*
4

7
41-
4k@ 01@

Photo: AFSC
The flatfish species complex has been managed flatfish assemblage into four categories: "shallow-
as a unit in the Gulf of Alqqka and includes the watee, natfish,,,deep-wateel flatfish, arrowtooth
major species of flatfish inhabiting the region. The flounder, and flathead sole. These classifications
major species, which compn .ise
98% of the current biomass, Flatf ish
include: arrowtooth flounder Gulf of Alaska
(Atherestes stomias), flathead
sole (Hippoglossoides 30 Catch (1.000 metric tons) Biomass (1,000 metric tons) 3000
elassodon), rock sole
(Pleuronectes bilineatus), rex 25 Survey-Biomas 2500
sole (Errex zachirus), Dover sole
(Microstomus pacificus),
yellowfin sole (Pleuronectes 20 2000
asper), and starry flounder 15 .-Catch 1500
(Platichthys stellatus). Gulf of
Alaska flatfish are relatively 1000
slow-growing, long-lived species
with similar biological character- 5 500
istics depending on the size of
the fish. 0
The NPFMC manages this 0 64 67 70 73 76 79 82 85 Be 91
resource and has divided the Year

44 Gulf of Alaska Groundfish Resources

are necessary because of rL&TFISH
the very different halibut
Gulf of Alaska
bycatch rates that occur COMMERCIAL CATCH (t)
in the directed fisheries
tMeting on shallow- and Year Foreign Joint Domestic Total
deep-water natnsh. venture
Arrowtooth flounder, ------------------------------------------------------------------
because of its present 1983 9,530 2,692 439 12,661
high abundance and low 1984 3,033 3,448 432 6,913
19:5 170 2,447 461 3,078
commercial value, was 19 6 71 961 1,409 2,441
separated from the 1987 0 7,207 2,718 9,925
shallow- and deep-water 1988 0 1,781 8,494 10,275
groups and is m 1989 0 0 5,167 5,167
anaged 1990 0 0 15,411 15,411
under a separate TAC 1991 0 0 20,068 20,068
limit. Flathead sole am 1992 0 0 28,000 28,000
likewise assigned a
separate limit because
they overlap the depth distributions of the shallow- For further, information
and deep-water groups.
The Gulf of Almkn flatfish resource has been Wilderbuer, T. K., and E. S. Brown. 1992. Flatfish.
underexPlOited since at least 1964. From 1978 to In Stock assessment and fishery evaluation document
1981, the fishery caught about 15,000 t annually (all for the 1993 Gulf of Alaska groundfish fishery, p.
species), which was nearly all the result of foreign 106-124. North Pacific Fishery Management
fishing in pursuit of non-flatfish species. By 1985, Council, P.O. Box 103136, Anchorage, AK 995 10.
the catch decreased to less than one-half this amount
as the fishery changed from foreign to joint venture
operations. Catches increased to 10,300 t in 1988
and to 15,400 t in 1990 as joint venture fishing
ceased and a near-shore domestic fishery developed
at Kodiak Island. Catch levels increased to 20,000 t
and 28,000 t for 1991 and 1992, respectively, but
remained well below the TAC for both years.
Flatfish abundance information
is available Erom three triennial FL&Triss
bottom trawl surveys conducted in Gulf of Alaska
the Gulf of Alaska from 1984 to
1990. Generally, flatfish stocks Average catch (1977-92) 12,200 t
have experienced a minimum of Long-term potential yield (MSY) 169,000 t
exploitation historically and are Acceptable biological catch (1992) - 466,750 t
believed to be at abundant, stable Exploitable biomass (1990 survey) =2,750,000 t
levels. Size-composition informa- Harvesting strategy wF0.1
Age/length at recruitment = 3-4 yrs/ ?
tion from the surveys indicate a Age/length at 50% maturity - 5 yrs/61 cm(females)
continuing presence of young fish Maximum age = 15+ years
recruiting to the flatfish popula-
tions. Abundance and trend High and Stable
Importance of recreational fishery = Minor
Management = GOA Groundfish FMP
Assessment Method = Trawl surveys
Status of exploitation = Under-exploited

M = 0.2-0.22 Fo., = 0.17-0.20, Fny = 0.3-0.6
F_fishuq = 0.24-0.30 F107-1-92 =very low

Gulf of Alaska Groundfish Resources 45

15. SABLEFISH

By Sanda A. Lowe and Jeffrey T. Fqftoka

The distribution of sablefish (Anoplopoma 4-6 years of age at sizes of 57-65 cm. Maximum age
fimbria) in North American waters ranges from the is 55+ years, and maximum size is about 100 cm.
waters off northern Mexico through the Gulf of Sablefish spawn at depths of 300-750 in generally
Alaska and along the Aleutian Island chain and during the winter months. They are carnivores;
edge of the continental slope in the eastern Bering adults feed primarily on fish and also nektonic and
Sea. Their range continues off the Siberia and benthic invertebrates.
Kamchatka coasts of Russia to the northeast coast of Sablefish of the Gulf of Alaska, eastern Bering
Japan. The resource is managed by discrete regions Sea, and Aleutian Islands are considered one Large
to distribute exploitation throughout its wide stock. They are managed by the NPFMC. This
geographical range. There are three management resource has been harvested by U.S. and Canadian
areas in the northeast Pacific Ocean: the eastern fishermen since the early 1900s, but catches were
Bering Sea, the Aleutian Islands region, and the relatively low until the Japanese longline fleet began
Gulf of Alqqka operations in the Eastern Bering Sea in 1958. The
Eggs, Larvae, and young-of-the-year juveniles are fishery rapidly expanded and catches peaked at
pelagic, but older juveniles and adults are demersal. 26,000 t in 1962. The Japanese fleet then expanded
They have a wide depth distribution--young juve- into the Aleutian Islands region and Gulf of Alaska
niles are found in surface and near-shore waters Catches in the Aleut= Islands region have histori-
down to depths of 150 in, older juveniles are found cally remained at low levels. In the Gulf of Alaska-
on or near the bottom in waters 100-200 m in depth, catches reached 37,500 t in 1972 and averaged about
and adults are found in waters 150-1,200 m in 28,000 t during 1973-76.
depth. The bulk of the exploitable population Evidence of declining stock abundance led to
occupies depths of 400-1,000 m. Sablefish mature at significant fishery restrictions Erom 1977 to 1985,

46 Gulf of Alaska Groundfish Resources

SABLZFISH
Eastern Bering Sea, Aleutian Islands and Gulf of Alaska
COMMERCIAL CATCH (1,000 t)

Category 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
-----------------------------------------------------------------------------------
Eastern Bering Sea
Foreign 2.6 1.2 0.2 0.1 0.0
Joint venture 0.0 0.1 0.0 0.3 0.1 0.0 0.0
Domestic 0.1 1.0 2.1 3.1 4.1 3.2 1.2 2.3 1.2 0.6
Subtotal 2.7 2.3 2.3 3.5 4.2 3.2 1.2 2.3 1.2 0.6

Aleutian Islands
Foreign 0.6 0.7 0.1
Joint venture 0.1 0.3 0.1 0.1 0.1 0.0
Domestic 0.0 1.3 2.9 3.8 3.4 3.2 2.2 2.1 1.4
Subtotal 0.7 1.0 1.5 3.0 3.9 3.4 3.2 2.2 2.1 1.4

Gulf of Alaska
Foreign 5.0 1.1 0.0 0.0
Joint venture 0.0 0.5 0.2 0.0 0.2 0.0
Domestic 3.8 8.6 12.2 21.6 26.1 29.9 29.8 25.7 19.6 20.8
Subtotal 8.8 10.2 12.4 21.6 26.3 29.9 29.8 25.7 19.6 20.8

Total 12.2 13.5 16.2 28.1 34.4 36.5 34.2 30.2 22.9 22.8

and total catches were reduced substantially. Total Sablef ish
catches increased steadily after 1983, reaching a Gulf of Alaska, Bering Sea,
peak of 36,500 t in 1988 with an ex-vessel value of and Aleutian Islands Oombined
$783 million. Total sablefish commercial catch in
the eastern Bering SeatAleutian Islands and Gulf of
Alaska in 1992 was 22,700 t valued at $51 million (Catch in 1,000 t) (RPW index Points)
(ex-vessel value). Ihis species is of minor recre- 60 @500
ational importance.
Stock-reduction analysis revealed declining stock 50 --
sizes through 1978. Estimates of exploitable RPW-Re1afivqB1ioma88- 400
biomass after 1979 were determined from survey
data by scaling indices of biomass from annual 40-
longline surveys to absolute biomass based on GOA Catch 300
comparisons of longline and bottom trawl survey
catch rates. The surveys indicted that stock biomass 30- B3A1 Catc
increased after 1980 and peaked in 1985 at nearly 200
400,000 t. Lower exploitation rates and a strong
1977 year class, which recruited in 1982, led to this 20 -
improved stock condition. After 1986, stock size has
been relatively stable but has shown a slight decline. 10
'0
Although stock size may be declining, there is no 10
evidence that it is being overfished. The decline is
attributed to the lack of significant recruitment in 04.11,11 0
recent years. Ile stock is at a high level and 56 61 r, C) 7.1 765 61 86 91
considered to be in good condition. Year
In the past, a constant F,., fishing rate policy was
applied to sablefish. Recent simulation studies have

Gulf of Alaska. Groundfish Resources 47

RABI ISH
Bering Sea, Gulf of Alaska, and Aleutian Islands

Average catch (1977-92) = 20,900 t
Long-term potential yield (MSY) = Unknown
Acceptable biological catch (1993) = 25,000 t
@Exploitable biomass (1993) - 227,400 t
Harvesting strategy F33% * (B93 IB351)
Age/length at recruitment = 5 yrs/60 cm
Age/length at 50% maturity = 4-6 yrs/57-65 cm
Maximum age = 55+ yrs
Abundance and trend = High and declining
Importance of recreational fishery = Minor
Management = GOA and BSAI Groundfish FMPs
Assessment Method - Stock-reduction analysis
and yield-per-recruit
Status of exploitation = Fully exploited

M = 0.10 F,., = 0. 13 FwY Unknown
F..,,"t'im = 0.16 0.09

been conducted to examine harvest strategies that
reduce the risk of overfishing. One of the strategies
that reduces this risk, in comparison to a constant
fishing rate strategy, is a variable rate that decreases
proportionately as biomass decreases below a
desirable reference level. Such a policy should
reduce risk without appreciably reducing average
catch levels. For 1993, sablefish were harvested
under an F., strategy adjusted by the ratio of current
biomass to B.. or (B,3iS3.,). The resource is
considered fiffly utilized.

For further information

Fujioka, J.T. 1992. Sablefish. In Stock assessment
and fishery evaluation report for the 1993 Gulf of
Alaska groundfish fishery. North Pacific Fisheries
Management Council, P.O. Box 103136, Anchorage,
AK 995 10.

Lowe, S A. 1992. Sablefish. In Stock assessment
and fishery evaluation document for the 1993 Gulf of
Alaska groundfish fishery. North Pacific Fishery
Management Council, P.O. Box 103136, Anchor-
age, AK 99510.

Sigler, M.F., and J.T. Fujioka. 1992. Harvest
policies for sablefish in the Gulf of Alaska. Proceed-
ings of the Symposium on Management Strategies
for Exploited Fish Populations. Lowell Wakefield
Fisheries Symposium, OCL 21-24, 1992. Anchorage,
Alaska.

48 Gulf of Alaska Groundfish Resources

16. SLOPE ROCKFISH

By David M. Clausen and Jonathan Heiefetz

Photo: AFSC
The NPFMC presently classifies 20 Gulf of the Gulf of Alaska.
Alaska rockfish species (genus Sebastes) into the Of the eight major species of slope rockfish,
slope rockfish assemblage. Slope rockfish are Pacific ocean perch has historically been the most
defined as those species of Sebastes that as adults abundant and provided most of the commercial
inhabit offshore waters of the outer
continental shelf and continental Slope Rockfish (Gulf of Alaska)
slope, generally in depths greater than Primarily Pacific Ocean Perch
150-200 in. Trawl surveys in the Gulf
of Alaska indicate that eight species of 400 Catch (1,000 metric tons) Biomass (1,000 metric tons) 1400
slope rockfish together comprise more 350
than 99% of the estimated total 300 1200
biomass for the assemblage: Pacific 1000
ocean perch (Sebastes alutus), 250 800
northern rockfish (S. polyspinis), 200 600
rougheye rockfish (S. aleutianus), 150
sharpchin rockfish (S. zacentrus), 100 400
redstripe rockfish (S. proriger), 50 200
harlequin rockfish (S. variegatus), 0 0
silvergray rockfish (S. brevespinis), 1960 1965 1970 1975 1980 1985 1990
and shortraker rockfish (S. borealis). Year
The remaining 12 species appear to POP Biomass Survey Biomass Catch

have a relatively sparse distribution in

Gulf of Alaska Groundfish Resources 49

catch. Almost all research
on slope rockfish has SLOPZ ROCKFISH
concentrated on Pacific (Primarily Pacific ocean perch)
Gulf of Alaska
ocean perch; little biological COMMERCIAL CATCH (t)
or assessment information is
available for the other
species. Consequently, this Year Foreign Joint Domestic Total
Venture
synopsis will deal mostly ---------------------------------------------------------------
with Pacific ocean perch. 1983 5,415 1,975 15 7,405
The Gulf of Alaska 1984 2,599 1,734 119 4,452
appears to be the center of 1985 8 254 825 1,087
1986 0 37 2,944 2,981
abundance for Pacific ocean 1987 0 112 4,869 4,981
perch, although the species 1988 0 8 13,771 13,779
ranges south to the coastal 1989 0 0 19,002 19,002
waters of southern Califor- 1990 0 0 21,114 21,114
1991 0 0 13,994 13,994
nia, north to the Bering Sea 1992 0 0 17,300 17,300
and west to the Pacific coast
of Russi& The species is
slow-growing and long-
lived; a maximum age of 78 years has been reported northern rockfish, which is found in shallower water
from the Gulf of Alaska Because of this slow on the outer continental shelf.
grow th and longevity, the estimated rate of instanta- The Pacific ocean perch stock was severely
neous natural mortality (0.05) is quite low compared depressed when the Japanese fishery ended in 1984.
with most other groundfish species. This species The stock apparently never rebounded from the
begins to recruit to the fishery at about age 5 and is overfishing that occurred in the 1960s. More recent
fully recruited by age 16, corresponding to fork assessments of Pacific ocean perch, based primarily
lengths of 27 cm and 40 cm, respectively. The on trawl surveys in 1984, 1987, and 1990, showed
maximum length recorded is 51 cm. The sparse that the stock was still low. There was, however,
information on other slope rockfish species indicates some evidence of successful recruitment, especially
that they are also slow-growing and long-lived. from relatively strong 1976 and 1980 year classes.
Commercial fishing for Pacific ocean perch in the The current stock condition is uncertain, although it
Gulf of Alaska began in the early 1960s by Soviet is still thought to be very depressed compared to its
and Japanese trawlers. Catches peaked in 1965 at former (pre- 1960) abundance. Recently, a stock
350,000 L Ile stock could not sustain this heavy synthesis model has been applied to Pacific ocean
level of exploitation, and catches declined precipi- perch that incorporates data from a variety of
tously in the late 1960s. This decline continued in sources, including past age compositions, biomass
the 1970s and early 1980s. When the foreign trawl estimates from the three trawl surveys, and CPUE
fishery was terminated in 1984, the catch of Pacific data from the commercial fishery. Based on this
ocean perch totaled only 4,500 L model, the current best estimate of exploitable
A significant domestic fishery for slope rockfish biomass for Pacific ocean perch is 153,600 L
developed in 1985, and catches increased annually In 199 1, the NPFMC divided the slope assem-
until 1990 when the total was 21,114 L In 1991 and blage into three management subgroups: Pacific
1992, catches diminished somewhat as a result of ocean perch, shortraker-rougheye, and "other slope
more restrictive management policies. The gross rockfish." The reason for this division was to
wholesale value of the 1992 trawl catch is estimated prevent possible selective overharvest of the more
at $22 million. Over the years of this domestic highly valued species in the assemblage. In 1993,
fishery, Pacific ocean perch has apparently been the the NPFMC further divided "other slope rockfish" by
major species caught. Recent fisheries, however, separating out northern rockfish as its own manage-
also target on shortraker and rougheye rockfish, two ment subgroup. Separate ABCs and TACs are now
larger sized species that inhabit deeper waters assigned to each of the four subgroups. Pacific
(greater than 300 m) of the continental slope, and on ocean perch is currently managed under an F3,,

50 Gulf of Alaska Groundfish Resources

PACMC OCEAN PERCH
(Dominant Slope Rockfish Species)
Gulf of Alaska

Average catch (1977-92) = 11,280 t (includes other species of
slope rockfish)
Long-term potential yield (MSY) = Unknown
Acceptable biological catch
(1993) = 5,560 t (21,580 t for assemblage)
Exploitable biomass (1993) = 153,600 t (457.036 t for assemblage)
Fishing strategy = F - F3,,; F = M for other species
Age/length at recruitment = 5-16 years/27-40 cm
Age/Length at 50t maturity = Males: 5.0-6.2 years/27.5-30.5 cm
Females: 5.4-10.0 years/28.5-36.3 cm
Maximum age = 78 years
Abundance and trend = Low and uncertain.
Importance of Recreational
Fishery = Minor
Management = GOA Groundfish FMP
Assessment level = Yield-per-recruit/stock synthesis
Status of exploitation = Fully utilized

M - 0.05 F0.1 = 0.08 FwY Unknown
F_rflehim = 0.08 F1977-92 awray. 0,07

harvesting strategy, whereas shortraker-rougheye,
northern rockfish, and "other slope rockfish" are
managed using an F = M strategy.

For further information

Heifetz, J., and D. M. Clausen. 1992. Slope
rockfish. In Stock assessment and fishery evaluation
report for the 1993 Gulf of Alaska groundfish
fishery. North Pacific Fishery Management Council,
P.O. Box 103136, Anchorage, AK 99510.

Heifetz, J., and J. N. Ianelli. 1992. Stock assess-
ment of Pacific ocean perch in the Gulf of Alaska
based on the stock synthesis model. In Stock
assessment and fishery evaluation report for the
1993 Gulf of Alaska groundfish fishery, Appendix
IV. North Pacific Fishery Management Council,
P.O. Box 103136, Anchorage, AK 99510.

Gulf of Alaska Groundfish Resources 51

17. PELAGIC SHELF ROCKFISH

By David M. Clausen and Jonathan Heifetz

Ile pelagic shelf DUSKY ROCKFISH
rockfish management (Dominant Pelagic Shelf Rockfish Species)
assemblage in the Gulf of Alaska
Gulf of Alaska
includes five species Average catch (1988-92) = 2,050 t (includes other
of Sebastes. These species of pelagic shelf
fish typically inhabit rockfish)
waters of the conti- Long-term potential yield (MSY) = Unknown
nental shelf of the Acceptable biological catch (1993) = 6,740 t
Gulf of Alaska and Exploitable biomass (1993) = 74,900 t
Harvesting strategy = F = M
exhibit a midwater Age/length at recruitment = Unknown/unknown
schooling behavior. Age/length at 50% maturity = Unknown/unknown
At times, however, Maximum age = 49 years
some of the fish am Abundance and trend = Both unknown
Importance of recreational fishery = Minor
found near the Management = GOA Groundfish FMP
bottom where they Assessment Method = Trawl surveys
Can be Captured Using Status of exploitation = Under-exploited
bottom trawls. M = 0.09 F0.1 = Unknown Fw, = Unknown
Dusky rockfish F@rflbinq = Unknown F2979-92 Unknown
(Sebastes ciliatus) is
the most abundant
species in the
assemblage. Trawl surveys have shown this species and 1992, however, a jig fishery for black rockfish
to comprise 92-99% of the total biomass for the (Sebastes melanops) developed in the central Gulf of
group. Most of this synopsis, therefore, will deal Alaska, and this fishery caught 500 t each year.
with dusky rockfish. The only stock-assessment information for
There is relatively little biological information on pelagic shelf rockfish comes from three bottom trawl
dusky rockfish. Ile species ranges from the waters surveys in the Gulf of Alaska. Estimated exploitable
off northern British Columbia to the Bering Sea and biomass for dusky rockfish in these surveys showed a
is apparently most abundant in the Gulf of Alaska. wide variation, from 37,313 t in 1994, increasing to
Maximum reported age is 49 years, but there are no 163,188 t in 1987, and falling to 24,141 t in 1990.
data on age or size of recruitment. A natural These large fluctuations do not appear to be reason-
mortality rate (M) has been recently estimated at able when one considers the low natural mortality
0.09, which indicates that dusky rockfish is rela- rate for dusky rockfish and the relatively small
tively fast-growing compared to most other rockfish commercial catches. One hypothesis is that some
species in Alaska. Dusky rockfish can attain a portion of the population may have moved off bottom
maximum length of 53 cm. in 1984 and 1990 and hence, was not captured in the
Catch statistics for pelagic shelf rockfish in the survey. Thus, present stock condition of pelagic
Gulf of Alqqka are only available beginning in 1988 shelf rockfish is uncertain, although dusky rockfish
when this management group was created. In are thought to be more abundant now am they were
general, catches have increased during this time in the 1960s and 1970s.
period. Nevertheless, they have remained much less Pelagic shelf rockfish are presently managed
than the assigned TAC, which indicates the assem- using an F = M strategy, in which ABC is deter-
blage has been underutilized. Most of the catch has mined by applying the natural mortality rate for
been dusky rockfish taken by bottom trawls. In 1991 dusky rockfish (0.09) to the exploitable biomass of

52 Gulf of Alaska Groundfish Resources

the assemblage. Due to the uncertainty of the trawl DUSKY ROCKFISH
survey results, the average of the exploitable (Dominant Pelagic Shelf Rockfish Species)
biomass estimates Erom the three surveys (74,889 t) Gulf of Alaska
is used for these Computations. COMMERCIAL CATCH (t)

For further information Western Central Eastern Total

---------------------------------------------
Clausen, D. M., and J. Heifetz. 1992. Pelagic 1988 400 518 168 1,086
shelf rockfish. ju Stock assessment and fishery 1989 113 888 737 1,738
evaluation report for the 1993 Gulf of Alaska 1990 165 955 527 1,647
215 1191 937 2,342
groundfish fishery. North Pacific Fishery Manage- 1991 73 2387 980 3,440
1992
ment Council, P.O. Box 103136, Anchorage, AK
99510.

Gulf of Alaska Groundfish Resources 53

18.DEMERSAL SHELF ROCKFISH

By Victoria M. O'Conneft and Jeffrey T. Fqfloka

The demersal shelf rockfish assemblage includes Waked in 1987 at 726 L Catches declined in 1988
eight species of rockfish that are found most com- to 505 t and further to 3 10 t in 1989. Much of the
monly near shore at depths less than 200 in off decline in harvest can be attributed to closures of the
Southeast Alaska The two most important species directed fishery for conservation. The TAC was
in the assemblage, yelloweye rockfish (Sebastes reduced Erom 660 t in 1988 to 420 t in 1989 and
ruberrimus) and the quillback rockfish (S. maliger) then increased to 470 t in 1990 to allow for an
are distributed from the waters off California to increase in bycatch. In 1991, the ABC was con-
Prince NNilliam Sound. The demersal shelf rockfish strained to 445 t, the mean catch since 1982 to 1989,
are managed by the NPFMC as a distinct assemblage as required by the NPFMC overfishing definition.
only off southeast Alaska where they are targeted by In 1992 the Southeast Outside district@ defined
a small shore-based fishery. Management in the for demersal shelf rockfish (DSR) management, was
EEZ is done jointly by the NPFMC with the expanded 20 west, to long. 14(r W. Since 1992
ADF&G. biomass has been derived from a combination of
Species in the demersal shelf rockfish assemblage density of yelloweye rockfishAan2estimates from
we ovoviviparous, with the majority of fish extrud- submersible line transects, areal estimates of
ing larvae in late winter and spring. Yelloweye available'!rocky" habitat, and mean weight data
rockfish extrude larvae over an extended time from the commercial fishery. In 1993, the ABC and
period, with the peak period occurring in April and TAC (800 t) were set by multiplying the lower end of
May. Like other rockfish, the demersal shelf the 90% confidence interval for biomass (40,049 t)
rockfish are considered to be slow-growing and long- by the natural mortality rate (0.02).
lived with a low natural mortality rate. The ages of Yelloweye rockfish, the primary target species,
yelloweye rockfish caught by the fishery range from accounted for over 85% of the landed weight in the
13 to 114 years, with first modes occurring around 1992 DSR longline fishery. Dernersal shelf rockfish
35 years of age *in I
lightly exploited SUCTS ROCKFISH CONPLEX
areas and around Gulf of Alaska
18-20 years in
exploited arms. Average catch (1982-92) = 450 t
Dernersal Shelf Long-term potential yield (MSY) = Unknown
rockfish have been Acceptable biological catch (1993) = 800 t
Exploitable biomass (1993) = 40,000 t
landed incidental Harvesting strategy = Accommodate directed and
to other fisheries bycatch fishery needs
in Southeast Age/length at recruitment = 20 years/51-54 cm
Alaska since the Age/length at 50% maturity = 20-25 years/47-49 cm
Maximum age = 114+ years
turn of the century Abundance and trend = Unknown and declining
In 1979, a small Importance of recreational fishery = Minor
shore-based Management = GOA Groundfish FMP
rockfish fishery and State of Alaska
Assessment Method = Yield-per-recruit with line
began, targeting transect density
primarily on this Status of exploitation = Local depletions
nearshore bottom-
dwelling complex. M = 0-02 F.., = 0. 03 FwY = Unknown
The directed F@rflshi'q = 0.04 F197"Sawmv' = Unknown
harvest of demer- (Values for age, length, M and F are for .9rJaa.&t= riihPrrJmiv%)
sal shelf rockfish

54 Gulf of Alaska Groundfish Resources

are also taken as bycatch
in the longline fishery for DFIelLSAL SHUY ROCKFISH
halibut and in trawl Gulf of Alaska
fisheries for "slope COMMERCIAL CATCH (t)
rockfish." While the
directed fishery harvest Category 1984 1985 1986 1987 1988 1989 1990 1991 1992
has been declining since ----------------------------------------------------------------
Directed 543 388 449 726 505 310 199 386 352
1987, the reported bycatch Incidental 20 100 41 47 53 103 128 119 215
has incremed dramati- Total 563 488 491 773 558 413 327 505 567
cally. The recreational
fishery is of minor
significance at this time; most fish are taken inciden-
tally and there is only occasional targeting on
yelloweye and quillback rockfish.
In past years, shifts in effort to grounds farther
from the port of landing have been noted in all five
Gulf of Alaska management areas. Considering that
most Southeast Alaskan processors limit trip time to
4 days and the additional cost associated with fishing
farther from port, the progressive expansion to more
distant fishing grounds is considered to be a strong
indication that abundance has declined near the
major ports.

For further information

O'Connell, V. M. 1987. Reproductive seasons for
some Sebastes species in Southeastern Alaska.
Alaska Dep. Fish and Game Info. Leaflet No. 263.
Juneau, AK.

O'Connell, V. M., and F. C. Funk. 1987. Age and
growth of yelloweye rockfish (Sebastes ruberrimus)
landed in Southeastern Alaska. Ln B. R. Melteff
(ed.), Proceedings of the International Rockfish
Symposium. p. 171-185. Alaska Sea Grant Report
No. 87-2.

O'Connell, V. M., D.W. Carlile, and B. E. Bracken.
1992. Demersal shelf rockfish. Ln Stock assessment
and fishery evaluation report for the 1993 Gulf of
Alaska groundfish fishery. North Pacific Fishery
Management Council, P.O. Box 103136, Anchorage,
AK 99510.

O'Connell, V.M., and D.W. Carlile. 1993. Habitat
specific density of adult yelloweye rockfish in the
eastern Gulf of Alaska. Fish. Bull., U.S. 91(2):
304-309.

Gulf of Alaska Groundfish Resources 55

19. THORNYHEADS

By Loh-Lee Low

W
Alrw@

PhotD: AFSC
71bornyheads of the northeastern Pacific Ocean expanded. The catch peaked in 1989 at 3,079 L
are comprised of two species, the shortspine Catches since 1991 have been close to the estab-
thornyhead (Sebastolobus alascanus) and the lished quota. In 1992, the ex-vessel value of the
longspine thornyhead (S. altivelis). The longspine catch was $1.7 million.
thornyhead is rare in the Gulf of Alaska. Shortspine Based on trawl survey data, abundance of
thornyheads occur demersally along the continental
slope from 100 to 1,500 rn in depth from Baja SHORTSPINE THORNYEZADS
California to the Bering Sea. In the Gulf of Alaska, Gulf of Alaska
greatest concentrations are found at 300 - 700 m. COMMERCIAL CATCH (t)
Thornyheads are slow-growing and long-lived
with maximum age in excess of 50 years and Year Foreign Joint Domestic Total
maximum size greater than 50 cm and 2 kg. Venture
lbornyheads are caught by trawl and longline gear --------------------------------------
with the bulk of the fishery occurring in late winter 1983 716 13 0 729
1984 165 19 24 208
or early spring through the summer. 1985 4 9 69 82
Thornyheads am managed under the Gulf of 1986 0 1 713 714
Alaska groundfish FW. Caches were mainly made 1987 0 20 1,943 1,963
by foreign fisheries until the early 1980s and were 1988 0 8 2,787 2,787
1989 0 0 3,079 3,079
less than 1,400 L The catch decreased markedly in 1990 0 0 1,646 1,646
1984 and 1985 because of restricted foreign fishing 1991 0 0 1,217 1,217
in the Gulf. In 1985, the U.S. catch surpassed the 1992 0 0 1,653 1,653
foreign catch for the first time as U.S. fisheries

56 Gulf of Alaska Groundfish Resources

thornyheads in the Gulf of Alaska SHORTSPIM THORWEEADS
has declined sharply from 123,000 t Gulf of Alaska
in 1984 to 99,000 t in 1987, and to
26,000 t in 1990. Since abundance
of thornyheads was first measured Average catch (1981-92) = 1,350 t
in 1984, landings have never Long-term potential yield (MSY) = Unknown
exceeded 6.5% of biomass, while Acceptable biological catch (1993) - 1,180 t
Exploitable biomass (1993) = 26,200 t
from 1984 to 1988, landings did Harvesting strategy = F35%
not exceed 4%. Age/length at recruitment = 16 yrs/25 cm
The MSY for thornyheads Maximum age = 62+ yrs
Abundance and trend = Low and declining
cannot be estimated. Acceptable Importance of recreational fishery = Minor
biological catches, however, were Management = GOA Groundfish FMP
estimated from survey biomass data Assessment Method = Yield-per-recruit
at 1,798 t for 1992 and 1,180 t for Status of exploitation = Fully exploited
1993. M = 0.05 F0.1 = 0.07 F,,, = 0.05 F,,,, 0.045
[email protected] 0.055 F.@_q. = 0. 03

For further information

Dawson, P. K. 1992. Thornyheads.
In Stock assessment and fishery
evaluation report for the 1993 Gulf
of Alaska groundfish fishery.
North Pacific Fishery Management
Council, P.O. Box 103136, Anchor-
age, AK 99510.

Gulf of Alaska Groundfish Resources 57

20. PACIFIC HALIBUT

By Pwrkk J. SuMan

The Pacific halibut,
Hippoglossus stenolepis, is the
largest member of the flounder
family Pleuronectidae with males
weighing up to 54 kg and females
weighing up to 230 kg. Commer-
cially caught Pacific halibut gener-
ally range in age from 8 to 17 years,
LIM
although the oldest recorded age for
a Pacific halibut is 42 years. Males
become sexually mature between the
ages of 7 and 13 years, while females
mature at 9 to 15 years. During the
spring and summer feeding periods,
Pacific halibut are found on the
continental shelf along the Pacific
coast of North America, with the
bulk of the population residing in the
Gulf of Alaska. In the winter, adult
A
Pacific halibut migrate to spawning
grounds along the continental slope.
The Pacific halibut population
has supported a directed longline
commercial fishery since the late
1800s. Longliners use gear consist-
ing of groundline, gangions, and
hooks. A skate of gear is commonly
made up of 1,800 ft of groundline, :9 -4 4*
with gangions attached every 18 ft
The J-shaped hook traditionally
attached to each gangion has
gradually been replaced by a more
efficient circle hook. Most of the
fleet now uses snaps to attach the
gangion to the groundline, although
some fishermen continue to use
'Tixed" gear with the gangions PhotD: WHO
permanently attached. and develop the Pacific halibut fishery. The fishery
In 1923, a Convention between Canada and the Js regulated by controlling catch through time and
United States established the International Pacific area closures in U.S. waters and by individual quota
Halibut Commission, originally called the Intema- management in Canada. In the United States, over
tional Fisheries Commission, to manage the Pacific 6,300 vessels were commercially licensed to operate
halibut resource. The Commission directs research in 1992, while in Canada, where an Individual
and establishes management regulations to preserve Vessel Quota System was implemented in 199 1,

58 Gulf of Alaska Groundfish Resources

435 vessels were eligible to fish.
In 1992, nearly 36,000 t of Pacific halibut P Iacific Halibut
were landed by the commercial longline
fishery: 3 1,000 t in the United States and Alaska, Canada, and Pacific Coast
5,000 t in Canada, with a total ex-vessel
value of $66 million (U.S.). The 1992 50- Catch (1,000 t) Biomass (1,000 0 250
harvest reflects a 3% increase in yield from
the 34,000 t of Pacific halibut commercially
landed in 199 1. Other removals of Pacific 40- -200
halibut in 1992 include 4,300 t landed by
recreational fisheries, 1,500 t wastage due to 30--- - 150
gear loss and discard, and 9,500 t lost to
mortality by fisheries not specifically directed
at halibut. 20----- - 100
The stock is assessed on an annual basis
using an area by area catch-at-age analysis.
The exploitable biomass was estimated to 10- -50
peak at 217,000 t in 1987 and 1988 after a
period of stock rebuilding. The population 0- 0
has declined since that time at an average 1974 1977 1980 1983 1986 1989 1992
rate of 7% per year. Strong 1977 and 1979 Year
year classes contributed to this build-up of the
stock with weaker year classes subsequently M Catch (U.S.) Catch (Canada)
contributing to the decline. Blomass
Research on optimal exploitation strate-
gies indicate that a constant 30% harvest rate
on the exploitable portion of the stock will
maximize the yield of Pacific halibut with
minimum risk to the popula-
tion. After accounting for
other removals this translates, PACIFIC HALIBUT
as a management objective, to a Alaska and the Pacific Coast
commercial harvest rate of 0.20
on the fully exploitable stock
with the instantaneous fishing Average catch (1977-92) = 28,520 t
mortality rate ranging from Long-term potential yield (MSY) = 30,000-36,000 t
Exploitable biomass (1992) = 161,000 t
0.05 to 0.25 for fish larger than Abundance and trend = High and declining
the 82 cm size limiL Directed Status of exploitation = Fully exploited
commercial fishing mortality Importance of recreational fishery = Major
rates on legal-sized Pacific Management = International Pacific
Halibut Commission
halibut were relatively constant Age/length at 50% maturity = Male 8 yrs/72 cm
during the period of stock Female 12 yrs/122 cm
increase averaging 0.20 during Assessment Method = Age structured
the years 1974 through 1985. M = 0.20 F0.1 0.16 Fmsy 0.22 F1112 = 0.33
More recently the fishing
mortality rate has increased to

Gulf of Alaska Groundfish Resources 59

an average of 0.32. The change in the average rate PACIrIC HALIBUT
results Erom a combination of factors including stock Alaska and the Pacific Coast
decline and an increase in fleet participation in the CATCH (1,000 t)
fishery.
YEAR RECREATIONAL COMMERCIAL TOTAL
For further information -------------------------- U.S.--Canada --------
---- ------

1983 1.0 19.9 3.3 24.2
International Pacific Halibut Commission. 1987. 1984 1.1 21.7 5.5 28.3
The Pacific halibut: Biology, fishery, and manage- 1985 1.6 27.6 6.3 35.5
1986 2.0 35.3 6.8 44.1
ment. 1PHC Tech. Rep. 22., 59 p. Int. Pacific 1987 2.2 34.6 7.4 44.2
Halibut Comm., P.O. Box 95W9, Seattle, WA 1988 3.1 37.2 7.8 48.1
98145-2W9. 1989 3.3 34.2 6.3 43.8
1990 3.6 32.1 5.2 40.9
1991 4.2 30.1 4.3 38.6
International Pacific Halibut Commission. 1990. 1992 4.0 31.1 4.6 39.7
Annual Report, 1990.40 p. Int. Pacific Halibut
Comm., P.O. Box 95009, Seattle, WA 98145-2009.

60 Gulf of Alaska Groundfish Resources

21. PACIFIC HERRING

By Mar G. Wespestad

f 71 7"

TIN"

@_X

V
MEW

Photo: AFSC
The Pacific herring (Clupea pallasi) occurs occur during the herring spawning period, which
throughout the Gulf of Alaska, Bering and Chukchi runs from late March in Southeast Alaska to late
Seas and have been reported to occur in the Arctic June in Norton Sound. A small amount of herring is
Ocean east to the Mackenzie River Delta. Major also harvested for sale or use as bait. The principal
concentrations of herring in the Gulf of Alaska occur bait fisheries occur in winter in southeastern Alaska
in the waters off Southeast Alaska, Prince William and in summer in
Sound, and Kodiak Island-Cook Met. In the Bering the Bering Sea PACIFIC EWMNG
Sea, major centers of abundance are northern Bristol around Unalaska Alaska
Bay and Norton Sound. In the Chukchi Sea and the Island. COMMERCIAL CATCH (t),
Arctic Ocean, abundance is low and commercial Current
concentrations of herring have been located only in herring fisheries YEAR Gulf of Bering
Kotzebue Sound. occur within the Alaska Sea
Herring have been exploited in Alaska since the State waters of ---------------------
late 1800s. Early fisheries produced salted and dried Alaska and am 1963 13,610 34,662
1984 18,431 28,103
herring. In the 1920s, herring began to be utilized managed by the 1985 18,085 36,625
in reduction fisheries in which oil and fish meal ADF&G. Herring 1986 20,725 29,324
were the principal products. The reduction fisheries were harvested in 1987 27,223 22,718
continued into the mid-1960s when high production the eastern Bering 1988 29,869 22,016
1989 9,557 25,778
of lower cost Peruvian anchovy oil and meal made it Sea EEZ by 1990 21,389 19,140
unprofitable to operate reduction plants in Alaska. foreign fisheries 1991 24,443 16,200
In the early 1970s, herring fisheries shifted to from 1959 to 1992 34,a48 31,739
harvesting roe-bearing herring. These fisheries 1980. In 1980,

Pelagic Resources 6 1

PACIFIC HERRING
Gulf of Alaska and Eastern Bering Sea

Gulf of Alaska Bering Sea
--------------------------------------------------------------------------------
Average catch (1977-92) 17,848 t 23,863 t
Long-term potential yield Unknown Unknown
Acceptable biological catch
(1992) 34,348 t 31,739 t
Fishing strategy 0.1 to 0.2 of 0.1 to 0.2 of
exploitable biomass exploitable biomass
Age of recruitment 3 years 4 years
Length/weigbt at recruitment 170 mm/85 g 220 mm/143 g
Maximum age 12 years 18 years
Abundance and trend Moderately-high Low and
and increasing declining
Recreational importance None None
Subsistence use Minor Major
Management Alaska Department
of Fish and Game
Assessment method Survey, Aerial survey,
age-structured age structured
Status of exploitation Fully utilized Fully utilized
Natural Mortality (M) 0.45 0.27

allocations ended and herring became a prohibited In 1992, 56,426 t of herring were harvested in
species in U.S. waters. Alaska with a total ex-vessel value of $30 million.
Pacific herring exhibit a south-to-north cline in 7le majority of the harvest was roe herring, and the
life history features. Near the southern end of their remainder was food and bait herring and roe on
range, herring have a shorter age span, an earlier kelp.
age of maturity, a higher rate of natural mortality,
and a smaller size at age. In Southeast Alaska, Gulf of Alaska -- Herring harvests in the Gulf of
herring mature at age 3 and have a maximum life Alaska have averaged 19,800 t since 1977. South-
span of about 10 years. Herring in the Togiak east Alaska and Prince William Sound roe-herring
region, however, mature at age 4 and a maximum fisheries have accounted for the bulk of the Gulf of
age of 18 years has been observed. Natural mortality Alaska catch. Catches in all Gulf of Alaska herring
also appears to increase with age in Pacific herring. stocks rose in 1992 due to the recruitment of a Gulf-
Mean length at age is greatest in herring spawn- wide strong 1988 year class.
ing in the southeastern Bering Sea (Togiak) and
decreases in herring found to the north (Norton Bering Sea -- Herring fisheries in the Bering Sea
Sound, Kotzebue). Off Southeast Alaska, the occur in spawning areas along the western Alaska
maximum size of herring is 248 mm and 210 g. In coasL Ni*r harvests occur in the Togiak area of
Prince William Sound (in the central Gulf of Bristol Bay and in Norton Sound, and smaller
Alaska), herring grow to a maximum of 252 mm and amounts are harvested in other areas. Inshore
220 g. In the Bering Sea, maximum length and herring fisheries developed in the Late 1970s as the
weight vary from 323 mm and 466 g in Togiak to foreign trawl and gill-net fisheries were phased out.
308 min and 359. g in Norton Sound. Catches rose from 14,000 t in 1977 to a peak catch
The ADF&G regulates and monitors 20 separate of nearly 37,000 t in 1985. Since 1985, the catch
herring fisheries. The information from these has been declining in the southeastern Bering Sea
fisheries is divided into Gulf of Alaska and Bering but has been increasing in the northeastern Bering
Sea components to provide a general overview of the Sea. As in the Gulf of Alaska, the Bering Sea catch
catch and status of Pacific herring in Alaska by area. improved in 1992 with the recruitment of a strong

62 Pelagic Resources

1988 year class. Norton Sound did
not have a fishery in 1992 due to ice Herring
coverage of the spawning grounds. Gulf of Alaska and Bering Sea
A portion of the Bering Sea
harvest is taken as bycatch 'in the 60- catch (1,ooo metric tons)
groundfish fishery. Bycatch cannot Gulf of AlaSka
be retained but is counted in the
50- M-E@-,ring Sea
catch. Bycatch has averaged 2,000-
4,000 L 40-

Stock Trends --Herring harvest 30---- -
levels are based on aerial surveys,
spawn deposition surveys, 20-
hydroacoustic surveys, and age
composition of commercial and test- 10-
fishing catches. Harvest levels are
generally set at 20% of the esti- 0
mated biomass, but can range down 77 79 81 63 85 87 89 1
to 10%. Exploitation thresholds Year
have been established for most
stocks below which fishing is not permitted.
In the Gulf of Alaska, the overall abundance of
herring is at moderate to high levels, although some
stocks are depressed or declining. A strong 1984
year class is reported to be present in most fisheries.
A very strong 1988 year class is reported in South-
east Alaska Prince William Sound, and other areas
are expected to further increase the abundance of
herring in the Gulf of Alaska in 1993.
In the Bering Sea, the abundance of herring
declined through the 1980s as the very strong 1977-
78 year classes which sustained the fisheries aged
and declined in abundance. In 1992, a strong 1988
year class also became evident in eastern Bering Sea
stocks. This year class is expected to increasl: stock
biomass in the near future.

For further information

Funk, F. 1993. Preliminary forecasts of catch and
stock abundance for 1993 Alaska herring fisheries.
Regional Information Rep. No. 5J93-06,109 p.
Alaska Dep. Fish and Game, 333 Raspberry Road,
Anchorage, AK 99518.

Pelagic Resources 63

SHELLFISH RESOURCES

By Jerry E. Reeves

JIL 0'

-4

_ftno A

OPP'.

PhotD: AFSC
The major shellfish resources off Alaska are king against the landing of females. In addition,
crab, Tanner crab, shrimp, and sea snails. quotas, time-area closures, fishing seasons, gear
The king and Tanner crab fisheries of the Bering restrictions and at-sea observers are used routinely
Sea and Aleutian Islands region are managed for management of the stocks. Commercial crab
cooperatively by the State of Alaska and the Fedezal fishing gear is restricted to pots (traps), and
govemmenL A FMP developed by the NPFMC recreational and subsistence fisheries are insignifi-
provides for delegation of management authority to cant compared to commercial landings except in
the Alaska Board of Fisheries, with the NPFMC areas which no longer have commercial harvests
having oversight authority. Thus the ADF&G and of former commercial species. Snail fisheries are
NMFS cooperate in assessment and management of basically undeveloped, although some limited
the fisheries. Alaska shrimp and crabs in the Gulf of exploratory operations have occurred in recent
Alaska are managed by the Alaska Board of Fisher- years.
ies. Management of Bering Sea snails is provided This section focuses primarily on the crab
for by a Federal Preliminary FUR resources of the Bering Sea and Aleutian Islands
For crab resources, minimum size limit is the region. The ex-vessel value of this resource was
primary management measure, as is the prohibition $326 million in 1990 and $294 million in 1991.

Shellfish Resources 65

22. KING CRABS

Photo: AFSC

Three species of king crab are harvested in
the Bering Sea/Aleutian Islands region. These King Crab
am the red king crab (Paralithodes Bering Sea and Gulf of Alaska
camtschaticus), the blue king crab (P. platypus),
and the brown or golden king crab (Lithodes Catch (1,000 t) Abundance (Millions)
aequispina). The red king crab fishery has the
longest commercial history and highest yield
and value when compared to the other two king
crab species. Ex-vessel value of king crab
landings declined 38%, from $132 million in
1990 to $82 million in 1991.

Red King Crab

Red king crabs are distributed in the shelf
waters of the North Pacific and Bering Sea from
100

may attain carapace lengths in excess of 200 mm
the Japan Sea to northern British Columbia, and

(8 in). The minimum size limit is usually 1960 1965 1970 1975 1980 1985 1990
165 mm (6.5 in) carapace width, and individuals Year
in the catch commonly average 2.5-3.0 kg (6-7
lb). For most stocks, male and female size at Catch (BS) Catch (GOA)
50% maturity is considered to be 120 mm and Abundance (BS)

66 Shellfish Resources

90 mm carapace lengths, respectively (4.7, 3.5 in). 199 1. Prerecruit male abundance in 1991 declined
Corresponding approximate ages of maturity are from 10 to 6 million crabs. The abundance of
6 and 5 years. mature females declined from 18 to 13 million crabs,
Four stocks of red king crabs are identified for and the spawning stock remains below average.
management in the Bering Sea/Aleutian Islands Fishing mortality on the mature stock in 1990 was
region: the Bristol Bay, Norton Sound, Dutch below F,.,.
Harbor, and Adak stocks. Fisheries are conducted
primarily in the fall and winter. Red king crab Dutch Harbor stock -- The Dutch Harbor red king
landings decreased 16% from 9,721 t in 1990 to crab fishery has been closed since 1982 when 196 t
8,178 t in 199 1, and value decreased 40% from were landed. The 1991 trawl survey conducted by
$105.1 in 1990 to $54.0 million in 1991. All stocks ADF&G indicated a low level of abundance for this
are at low levels of abundance compared to historic stock. Based on the continuing low stock condition
levels. observed in 1987, 1990, and 1991 ADF&G surveys,
the fishery remained closed in 199 1.
Bristol Bay stock - The 1991 catch of red king crab
in Bristol Bay decreased 16% Erorn 1990 (9,236 t to RED KING CRAB
7,792 t), and remained below average for this stock, Bering Sea/Aleutians Region
and substantially below the record high production Commercial Landings (t)
of 59,OW t in 1980. Effort by 302 vessels making YEAR Bristol Dutch Adak Norton TOTAL
324 landings during the 1- 8 November season Bay Harbor Sound
decreased 13% from 1990 (262,131 to 227,555 pot -------------------------------------------
1983 0 0 .899 183 1,082
lifts). The CPUE (number of legal crabs per pot lift) 1984 1,897 0 620 193 2,710
remained unchanged at 12. 1985 1,894 0 411 208 2,513
The 1991 NUFS summer survey indicated that 1986 5,168 0 323 235 5,726
abundance declined from the 1990 level. The 1987 5,574 0 551 159 6,284
1988 3,351 0 711 113 4,175
abundance of males greater than 109 mm and 1989 4,656 0 507 120 5,283
females greater than 89 mm carapace length, 1990 9,236 0 376 109 9t721
corresponding approximately to the mature stock, 1991 7,792 0 431 15 8,178
was 31 million male crabs in 1991 compared to 1992 3,629 0 n.a. 58
37 million in 1990. The stock of legal males
increased from 9 million in 1990 to 12 million in

IUW KING CRAB
Bering Sea/Aleutians Region

Bristol Dutch Adak Norton
Bay Harbor Sound
------------------------------------------------------------------------------------------
Long-term potential catch (t) 15,948 2,653 1,395 344
Importance of non- minor minor minor minor
commercial fishery
Management By State of Alaska and Federal FMP
Status of exploitation All stock are fully exploited
Age at 50% maturity males 6 unknown unknown unknown
females 5 unknown unknown unknown
Size at 50% maturity males 120 120 120 90
Carapace length(mm) females 90 90 90 70
Assessment method Spawning stock Index Index Index
Parameters (mature males)
M 0.3 0.3 0.3 0.3
F(O.1) 0.35 0.35 unknown 0.35
F(MSY) =F(O.1) =F(O.1) =M =F(O.1)
F(91) 0.18 unknown unknown 0.02

Shellfish Resources 67

Adak stock -- The 1991 red king crab catch of 371 t BLUZ XING CRAB
at Adak remained similar to the 1990 catch and Bering Sea/Aleutians Region
remained below high production levels of the 196N COMMERCIAL LANDINGS (t)
and 1970s. Effort by seven vessels making 24
landings during the I November-15 February season Year Pribilofs St.Matthew Total
increased 7% over 19% (10,674 to 11,407 pot lifts). ------------------------------------
Catch per unit effort decreased Erom 14 to 12. 1983 995 4,288 5,283
The Adak stock has not been surveyed since 1984 139 1,708 1,847
1977, but the ADF&G Mandatory Observer Program 1985 242 1,101 1,343
instituted in 1988 provides data on stock condition. 1986 117 455 572
1987 318 488 806
This information indicates the stock is stable but 1988 0 601 601
depressed in comparison to historic catch levels. 1989 0 529 529
Fishing mortality in 1991 was unknown. 1990 0 783 783
1991 0 1,530 1,530
Norton Sound stock -- The 1991 catch of red king 1992 0 1,134 1,134
crab in Norton Sound decreased 86% from 1990
(109 to 15 t), and was below the recent-year
average. This amount was caught during the RLUZ I=r. can
winter commercial fishery and by subsistence Bering Sea/Aleutians Region
permit holders. There was no summer
commercial fishery in 1991. Pribilofs St. Matthew
The stock was surveyed in 1991 by NMFS. ------------------------------------------------
Results indicate a population of mature crabs Long-term potential catch (t) 1,545 1,276
of 2.1 million, down somewhat from the Importance of non- Minor Minor
2.5 million estimated in 1988. Fishing commercial fishery
Management State/ State/
mortality in 1990 was below F,,.,. Fed.FMP Fed.FMP
Status of exploitation Fully- Fully-
Blue King Crab Exploited Exploited
Age at 50% maturity Unknown Unknown
Size at 50% maturity males 120 105
Blue king crabs are distributed in the carapace length(mm) females 90 80
continental shelf waters of the North Pacific Assessment method Index Index
Parameters (mature males)
Ocem and Bering Sea from the Japan Sea to M 0.3 0.3
the waters off Southeast Alaska, although they F(O.1) 0.35 0.35
do not occur in the Aleutian Islands region. F(MSY) =F(O.1) =F(O.1)
Two stocks of blue king crabs am identified F(91) 0.00 0.22
for management in the Bering Sea region: the
Pribilof Islands stock and the St. Matthew
Island stock. These two stocks have notice- 50% maturity for males and females is 105 min and
ably different characteristics. Blue king crabs 80 mm carapace length, respectively. Fisheries are
in the Pribilof Islands may attain a carapace conducted in the fall. Blue king crab landings
length in excess of 200 min (8 in). The increased 95% in 1991 (783 t to 1,530 t), with
minimum size limit is 165 mm (6.5 in) commercial value increasing 63% ($5.8 to
carapace width, and individuals in the catch $9A million). Both stocks are at low levels.
commonly average 3.0-3.5 kg (7-8 lb). Male
and female size at 50% maturity is considered Pribilof Islands stoc -- The blue king crab fishery
to be 120 min and 90 mm carapace length, around the Pribilof Islands has been closed since
respectively. Blue king crabs Of the St. 1987 when 318 t were landed. The 1991 NMFS
Matthew stock are smaller. The fishery is summer survey indicated that abundance of the
managed with a minimum size limit of mature stock increased over 1990 but stiff remains at
140 mm carapace width, and individuals in a relatively low level. Males greater than 109 mm
the catch average 2.0-2.5 kg (4-5 lb). Size at and females greater thaii 89 mm carapace length,

s
6 8 Shellfish Resource

corresponding approximately to the mature stock, dance was 1.5 million in 199 1, compared to
increased to 4.8 million crabs in 1991 compared to 0.8 million in 1990. The abundance of mature
4.3 million in 1990. The stock of legal males males, used as an index of the spawning stock, was
increased from OA to 1.0 million crabs in 1991. 3.7 million in 1991 compared to 2.4 million in 1990.
Prerecruit male abundance decreased somewhat in Fishing mortality on the mature male stock in 1991
199 1. The abundance of mature males, considered was below Fy.
an index of spawners, was unchanged in 1991. Ile
stock has been at a depressed level since 1984 but, as Brown King Crab
indicated by prerecruit abundance, is now showing
some signs of recovery. Brown (golden) king crabs are distributed in the
St. Matthew Island stock -- The 1991 blue king crab continental slope waters of the North Pacific Ocean
catch around St. Matthew Island increased and Bering Sea from Japan to British Columbia. In
95% over 1990 (783 t to 1,530 t) but remained BROWN KING
below average and substantially below the high Bering Sea/Aleutians Region
production years 1982 and 1983. Effort by 68 Commercial Landings (t)
vessels making 69 landings during the 16-20
September season increased 4 1 % from 1990
(26,264 to 37,104 pot lifts). Catch per unit YEAR Adak Dutch Pribilof Northern TOTAL
Harbor
effort increased 33% (15 to 20). The 1991 ------------------------------------------------
NUFS summer survey indicated that abun- 1983 3,687 821 388 0 4,335
dance increased over the 1M level. The 1984 1,442 690 0 0 2,132
abundance of males greater than 104 mm and 1985 5,046 893 c 0 5,939
1986 5,805 848 c 0 6,653
females greater than 79 mm carapace length, 1987 3,629 627 c 193 4,449
corresponding approximately to the mature 1988 4,119 701 c 73 4,893
stock, was 4A million crabs in 1991 compared 1989 4,610 840 c c 5,450
to 2.6 million in 1990. The stock of legal 1990 2,382 780 0 0 3,162
1991 2,837 657 0 0 3,494
males, 1.7 million crabs in 1990, was c = confidential
2.2 million in 199 1. Prerecruit male abun-

BROWN KING CRAB
Bering Sea/Aleutians Region

Adak Dutch Pribilof Northern
Harbor

----------------------------------------------------------------------------------------
Long-term potential catch (t) 3,146 681 0 37
Importance of non- Minor Minor Minor Minor
commercial fishery
Management -- By State of Alaska and Federal FMP --
Status of exploitation Unknown Unknown Under- Under-
Exploited Exploited
Age at 50% maturity males Unknown Unknown Unknown Unknown
females Unknown Unknown Unknown Unknown
Size at 50% maturity males 109-130 130 107 92
Carapace length(mm) females 106-113 ill 100 98
Assessment level Index Index Index Index
Parameters (mature males)
M 0.3 0.3 0.3 0.3
F(O.1) Unknown Unknown Unknown Unknown
F(MSY) = M = M = M = M
F(91) Unknown Unknown 0 0

Shellfish Resources 69

most management areas the minimum size limit is Stevens, B.G., R.A. MacIntosh, J.A. Haaga, and J.H.
152 mm (6.0 in) carapace width, and individuals in Bowerman. 1993. Report to industry on the 1993
the catch commonly average 1.4-2.3 kg (3-5 lb). eastern Bering Sea crab survey. AFSC Processed
Male and female size at 50% maturity is in the range Rep. 93-14,53 p. Alaska Fish. Sci. Cent., Nad. Mar.
of 92-130 mm and 98- 111 mm carapace length, Fish. Serv., NOAA, P.O.Box 1638, Kodiak, AK
respectively. 99615.
Four stocks of brown king crabs are identified for
management in the Bering Sea/Aleutian Islands
region: Adak, Dutch Harbor, Pribilof Islands, and
Northern Bering Sea stocks. Fisheries are conducted
in the fall through the spring. Brown king crab
landings increased 10% from 1990 to 1991 (3,162 t
to 3,494 t), but value decreased I I% from $20.92 to
$18.5 million.

AdakjLQdL- The 1991 brown king crab catch from
Adak increased 19% over 1990 (2,382 t to 2,837 t).
Effort by 16 vessels making 206 landings during the
I November-15 August season increased 20% over
1990 (160,960 to 192,949 pot lifts). Catch per unit
-effort remained the same at 8 legals; per poL
This stock has not been surveyed. Fishing
mortality on the stock in 1991 was unknown.

Dutch Harbor stock -- The 1991 catch from the
Dutch Harbor brown king crab stock decreased 16%
from 1990 (780 t to 657 t). Effort by 11 vessels
making 50 landings during the I September-15
November season decreased 26% over 1990 (54,618
to 40,604 pot lifts). Catch per unit effort of legal
males was 8.
This stock has not been surveyed, and fishing
mortality on the mature stock in 1991 was unknown.

Pribilof Islands and Northern Bering Sea stocks --
Fisheries in these districts have been sporadic during
the last 10 years. No effort was expended in the
Northern Bering Sea in 199 1. No population
estimates are available for these stocks, and while no
estimates of F are available due to limited fishery
data, F is probably below F.Y.

For further information

Alasks, Department of Fish and Game. 1992. Annual
management report for the shellfish fisheries of the
Westward region, 199 1, Regional Information
Report 4K92-9, 216 p. Div. Comm. Fish., 2 11
Mission Rd., Kodiak, AK, 99615.

70 Shellfish Resources

23. TANNER AND SNOW CRABS

L
lie

-Aww-

Photo: AFSC
Wo species of Chionoecetes 6rabs are harvested
in the Bering Sea/Aleutian Islands region: C. bairdi, Tanner Crab; Chionoecetes
commonly known as the Tanner crab, and C. opilio, Bering Sea and Gulf of Alaska
commonly known as the snow crab. During the
1960s and 1970s C. bairdi stocks provided the major 200- Catch (1,000 t) Abundance (Billions) 12
production of Chionclecetes crab. Since the early
1980s, C. opilio has been the major Tanner crab
species harvested in Alaska. Landed value of these -10
fisheries increased from $194 million to 150-
$212 million from 1990 to 1991. -8

Tanner crab 100- -6

Tanner crabs are distributed on the continental -4
shelf of the North Pacific Ocean and Bering Sea 50-
from Kamchatka to Oregon. The males of this -2
species may attain a carapace width in excess of
180 min (7 in). The minimum size limit is 140 mm 0 'PT 1 1177-0
(5.5 in) carapace width, and individuals in the catch 60 65 70 75 80 85 90
commonly average 0.9-1.1 kg (2-2.5 lb). Male and Year
female size at 50% maturity is considered to be
110 mm and 90 min carapace width, respectively. Catch (BS) Catch (GOA)
The corresponding approximate age of maturity is C. baircl nos C opilio nos.
6 years.

Shellfish Resources 71

Tbree stocks of Tanner crabs are identified for Western Aleutians stock -- Tanner crab landings
management in the Bering Sea/Aleutian Islands from the Western Aleutians stock in 1991 decreased
region: Bering Sea, Eastern Aleutians, and Western 68% below 1990 levels (22 to 7 t). Effort by five
Aleutians stocks. Fisheries are conducted primarily vessels making 21 landings during the 1 November-
in the winter and spring. Tanner crab landings 25 March season decreased 79% from 1990 (6,204 to
decreased 51% in 1991 (29,416 t to 14,453 t). Ex- 1,309 pot lifts). Catch per unit effort increased from
vessel value of the fisheries was $47.8 million in 4 to 5. With the exception of a few of the smaller
1991. vessels in this district, the catch of Tanner crabs is
considered incidental to the red and brown king crab
Bering Sea stock -- The 1991 catch of Bering Sea fisheries in the same area. The current level of
Tanner crabs decreased 5 1 % from 1990 levels fishing mortality on this stock is unknown.
(29,316 t to 14,423 t). This drop is an artifact of
season changes occuring in 1990. The catch has
actually been on an increasing trend which began in
1988. Effort by 258 vessels making 761 landings
during the 15 November-31 March season decreased
44% from 1990 levels (883,391 to 499,277 pot lifts). TANNM CRAB (Chlonodamptan
Catch per unit effort increased from 19 to 21. Bering Sea/Aleutians Region
IMe 1991 NMFS summer survey indicated the Commercial Landings (t)
stock continued to increase as it has in the last few
years. The abundance of males greater than 109 MM YEAR Bering Sea Eastern Western TOTAL
and females greater than 84 mm carapace width, Aleutian Aleutian
corresponding approximately to the mature stock, --------------------------------------------
was 268 million crabs in 199 1, compared to 1983 2,392 248 222 2,862
1984 548 109 174 831
230 million in 1990. The mature stock has been 1985 1,430 75 74 1,579
increasing since 1985. The stock of legal males 1986 0 76 94 170
decreased from 54 million in 1990 to 46 million in 1987 0 73 19 92
1991. Prerecruit male abundance in 1991 was up 1988 1,003 141 64 1,208
1989 3,181 148 68 3,397
from 1990 levels (79 million to 105 million). The 1990 29,316 78 22 29,416
abundance of mature males has likewise increased 1991 14,423 23 7 14,453
(133 million in 1990 to 151 million in 1991).
Fishing mortality on the mature stock in 1991 was
below F.-,
Eastern Aleutians stock -- TANNER CRAB
The catch of Tanner crab Bering Sea/Aleutians Region
from the Eastern Aleutians
stock in 1991 decreased 71% Bering Sea Eastern Western
below 1990 levels (78 t to 23 Aleutian Aleutian
---------------------------------------------------------------
t). Effort by five vessels Long-term potential catch W 11,574 266 89
making 27 landings during Importance of non-commercial - ------------ Minor -----------
the 15 January-31 March fishery
season decreased 73% from Management ----- State/Federal FMP ------
1990 (6,858 to 1,849 pot Status of exploitation Fully-exploited Unknown Unknown
Age at 50% maturity (both sexes) 6 Unknown Unknown
lifts). Catch per unit effort Size at 50% maturity (males) 110 Unknown Unknown
increased from I I to 12. A Carapace width(mm) (females) 90 Unknown Unknown
survey of this stock by the Assessment method Yield Index Index
ADF&G during summer Assessment parameters (mature males)
M 0.3 0.3 0.3
1991 indicated a very small F(O.1) 0.34 Unknown Unknown
C. bairdi population. F(MSY) = F(O.1) = M = M
Fishing mormlity in 1991 F(91) 0.09 Unknown Unknown
was unknown.

72 Shellfish Resources

Snow crab SNOW CRAB aa=Q)
Bering Sea
Snow crabs (C. opilio) are distributed on
the continental shelf of the Bering Sea, Stock = Bering Sea
Chukchi Sea, and in the western Atlantic Long-term potential catch = 28,951 t
Ocean as far south as Maine. A subspecies, Importance of non-commercial fishery = Minor
C.o. elongatus, occurs from the Japan Sea to Management = State/Fed.FMP
status of exploitation = Fully-exploited
the Okhotsk Sea. The males of this species Age at 50% maturity (males & females) = 4
may attain a carapace width in excess Of Size at 50% maturity males = 65
152 mm (6 in). In U.S. waters a market Carapace width(mm) females = 50
minimum size of about 102 mm carapace Assessment le'vel = Yield
Assessment parameters (mature males)
width is in effect, and individuals in the catch M = 0.3
commonly average 0.5-0.7 kg (1-1.5 lb). Male F(O.1) = 0.25
and female size at 50% maturity is considered F(MSY) = F(O.1)
to be 65 mm (2.6 in) and 50 min (2.0 in) F(91) = 0.16
carapace width, respectively. Ile correspond-
ing approximate age of maturity is 4 years.
Snow crabs of the eastern Bering Sea are consid- Stevens, B.G., R.A. SNOW CRAB
ered to be one stock. Fisheries are conducted MacIntosh, J.A. (Chinnoecates ontlio)
primarily in the winter and spring. Snow crab Haaga, and J.H. Bering Sea
landings jumped 103% in 1991 (73,402 to Bowerman. 1993. Commercial Landings (t)
149,073 t), and value increased 59% ($103.6 to Report to industry 1983 11,852
$164.3 million). Effort by 228 vessels making 2,788 on the 1993 eastern 1984 12,162
landings during the 15 January -23 June season Bering Sea crab 1985 29,937
increased 53% over 1990 (911,613 to 1,391,583 pot survey. AFSC 1986 44,445
lifts). Catch per unit effort increased 35% (139 to Processed Rep. 93- 1987 46,223
188 legal crabs per pot lift). The 1991 NMFS 14, 53 p. Alaska 1988 60,809
1989 67,793
summer survey indicated that the mature stock Fish. Sci. Cent., 1990 73,402
remains high. Abundance of males greater than Natl. Mar. Fish. 1991 149,073
64 mm and females greater than 49 mm carapace Serv., NOAA, 1992 143,020
width, corresponding approximately to the mature RO.Box 1638,
stock,, was 5,215 million crabs in 199 1, compared to Kodiak, AK 99615.
4,748 million in 1990. Abundance of large males
increased from 420 million in 1990 to 484 million in
199 1. Prerecruit male (80-104 mm) abundance in
1991 decreased from 1990 (1,077 million to
708 million). Ile abundance of mature males
decreased from 1,949 to 1,640 million. Fishing
mortality on the mature stock in 1991 was below
F,,r

For further information

Alaska Department of Fish and Game. 1992. Annual
management report for the shellfish fisheries of the
Westward region, 199 1, Regional Information
Report 4K92-9,216 p. Div. Comm. Fish., 211
Mission Rd., Kodiak, AK, 99615.

Shellfish Resources 73

24. SHRIMP AND SEA SNAILS

The U.S. fishery for shrimp in -Q*-
Alaskan waters is currently at a
low level. The western Gulf of
*3
Alaska has been the main area of
operation. During the 1970s,
when the fishery was at a higher ot
level of productivity, from 50 to
100 vessels trawled for shrimp
(primarily Northern pink shrimp,
Pandalus borealis) off Kodiak and Z LMAA@W
along the Alaska Peninsula.
4
Stocks are managed by regulating
the level of exploitation rates
according to the level of the
stocks. In addition, spring "egg
hatch" closures are utilized to
protect breeding stocks.
From the 1960s, catches rose
steadily to about 58,000 t in 1976,
and declined precipitously after
that time. Since 1988, no shrimp
has been landed from western
IMP=, i@@
Alaska. During the 1960-90
period, the ex-vessel value of
western Alaska shrimp fisheries
VFW W -@j
averaged $4 million annually, with
a peak value of $14 million in
1977.
Shrimp catches by the U.S.S.R.
and Japan in the Bering Sea rose Photo: AFSC
to a peak of 32,000 t in 1963, and
gradually declined thereafter, until the fishery ceased ture regimes.
operation in 1973. The potential yield for shrimp Neptunea SFJL SNAILS
stocks is not well understood. The LTPY has been pribiloffensis and Bering Sea/Aleutians
estimated using the 20-year average catch. N. lyrata are Commercial Catch (t)
The snail resource of the eastern Bering Sea is typically found in
composed of about 15 species which are patchily deeper, warmer YEAR CATCH
distributed over the continental shelf. Neptunea waters at the shelf ----------------------
pribiloffensis is probably the most abundant species, edge, while N. 1982 841
1983 1,207
with other members of the genus, N. lyrata, N. heros and N. 1984 852
ventricosa, and N. heros also very common. Mean ventricosa inhabit 1985 389
shell lengths for these species range from 100 to shallower coastal 1986 1,826
120 mm. Fusitriton oregonensis is another abun- waters. Neptunea 1987 3,267
.1988 0
dant species and reaches a length of 130 mm (5.1 pribiloffensis, N. 1989 0
in). Several species of the genus Buccinum are also lyrata, and 1990 0
common to the area, but they am smaller with F oregonensis 1991 0
average shell lengths ranging 58 to 75 mm. Most make up the bulk
species are restricted to specific depth and tempera- of the snail

74 Shellfish Resources

biomass in the eastern Bering Sea.
Life histories are similar among species. Sexes Shrimp and Snail
are separate and fertilization is internal. Among Bering Sea and Gulf of Alaska
larger species, maturity occurs at 90-110 mm Catch (1,000 metric tons)
lengths, which probably correspond to an age of 80-
about 10 years. Young are hatched from egg cap-
sules, and almost all species have no larval stages. 70 - ---
Egg cases are usually laid on both live and dead
shells of large snails, and vary in the number of 60--
individual capsules they contain. Little is known
regarding feeding habits of snails, but they are 50-
probably predators and scavengers.
40-
Japan has harvested snails from the eastern
Bering Sea since at least 1971, the last year of 30--
operation being 1987. The average annual catch of
whole animals during that period was approximately
4,800 L Only fragmentary information is available
regarding other aspects of this fishery.
Neptunea pribiloffensis accounted for 70% of the
catch and meat yields were about 30%. Probably 0_@
less than 20 vessels participated in the fishery 60 65 70 75 80 85 90
annually, ranging in size from 96 to 490 gross t, and Year
similar to vessels used in Japanese longline and crab -Shrimp (BS) Shrimp (GOA) Snail (13S)
fisheries off Alaska. Fishing gear consisted of baited
pots (traps) attached at intervals along
groundlines. Ex-vessel value in the late SEA SNAILS
1970s ranged between $6W and Bering Sea/Aleutians Region
$1,657 per t, with the value of the 1978
catch estimated at $1.3 million.
There is currently no U.S. fishery for Long-term potential catch 4,800 t
Importance of recreational fishery = None
snails in the Bering Sea, although one vessel Management = PFMP
was permitted to fish in 1990. There am no Status of exploitation Underexploited
estimtes of biomass available, and fishing Spawning stock abundance = Unknown
mortality and other population parameters Age at 50% maturity (male and female) = 10
Size at 50% maturity (male and female)= 90-110
am unknown. Shell length (mm)
Assessment method = History
For further information Assessment parameters = Unknown

MacIntosh, R.A. 1980. The snail resource of
the eastern Bering Sea and its fishery. Mar.
Fish. Rev. 42(5):15-20.

Shellfish Resources 75

ALASKA SALMON RESOURCES
By James C. Olsen

M @_@

4. Ku

Photo: AFSC

The Pacific salmon fisheries in Alaska contrib- freshwater rearing for Pacific salmon: (1) migration
ute to the food supply and economy of the Nation to saltwater upon emergence from the gravel,
and rank as the largest non-governmental employer typical of pink and chum salmon; (2) short-term
in Alaska with recent sales exceeding those of rearing in fresh water with migration to sea in the
tourism, mining, or forest products. The fisheries first year of life, typical of ocean-type (fall)
provide recreational opportunities and are an chinook, some sockeye, and some chum popula-
integral part of Alaska native culture and heritage. tions; and (3) at least one winter rearing in fresh-
Recent catches exceed 155 million salmon and water streams or lakes after emergence with
include about 20 million salmon from the Alaska migration to sea at age I or older-, typical of coho,
enhancement projects. Ex-vessel value of the 1992 stream type (spring) chinook, and most sockeye
catch was about $575 million. populations.
Pacific salmon are anadromous. Their life cycle In the North Pacific Ocean, salmon from Alaska
begins with the deposition of eggs by spawning feed with other North American stocks and migrate
adults in redds (nests) dug in streambeds or lake thousands of miles and mix with stocks from Asia.
bottoms. Some pink and chum populations spawn Some stocks will migrate into international waters
in or just above intertidal areas. Eggs incubate outside of the U.S. EEZ. Length of stay in the
several months in the gravel before the young ocean varies with species from 1 year to 6 years.
salmon (alevins) are ready to hatch. After hatching Pink and coho salmon typically spend one winter at
the alevins remain in the gravel nourished by the sea; chum and sockeye salmon spend from 2 to
egg yolk before emerging from the gravel as ready- 5 years; and chinook salmon may spend up to
to-feed salmon fry. There are three basic patterns of 6 years. Growth in ocean areas is rapid. Average

Alaska Salmon Resources 77

weight at maturity is 3-5 lb for pink, 5-8 lb for In Alaska, all five species of Pacific salmon are
sockeye, 10-15 lb for chum, 7-12 lb for coho, and fully utilized. Most stocks have generally rebuilt to
17-50 lb for Chinook salmon. As Alaska stocks or beyond previous high levels. On a regional basis,
return to natal spawning areas, they mix with stocks some stocks are not rebuilding and may be overuti-
from British Columbia, the Yukon Territory and the lized and may be at risk. Declining escapement of
Pacific Northwest along the Alaska coast. some stocks in the three ADF&G management
Management of Pacific salmon in the vast regions (southeast, central, and western) has been
Alaska region requires a complex mixture of observed. The reasons for the declines are not fully
domestic and international bodies, treaties, regula- understood but causes may include impacts on
tions, and agreements. Salmon management in the spawning and rearing habitats from industrial
EEZ is under the responsibility of NMFS and the activities, decreasing ocean temperatures, reduced
NPFMC for the coast of Alaska from 3 to 200 miles food abundance at early life stages, bycatches in
offshore. In state waters, where most fisheries other fisheries, illegal high-seas fishing, and
occur, fisheries are managed by the ADF&G. competition in ocean feeding areas from Asian
Catches of Alaska salmon in high-seas fisheries hatchery salmon.
outside the U.S. EEZ can be significant. As of
1993, the high-seas salmon fishery of Japan has
been terminated under a new "Convention for the
Conservation of Anadromous Stocks for the North
Pacific Ocean." The other type of high-seas fishery
that can catch significant numbers of salmon, the
squid-driftnet fishery, has also been terminated
under the United Nation's General Assembly
Resolution 46/215.
The complexity of managing fisheries on
mixtures of salmon stocks from several regions and
from two countries is illustrated by the Pacific
Salmon Treaty between the United States and
Canada. Signed in 1985, the Treaty established the
Pacific Salmon Commission (PSC) and provides
principles for salmon stock management to reduce
interceptions and to establish equity in Catches off
the Pacific Northwest, British Columbia, and
Southeast Alaska. The U.S agencies involved
include state management agencies in Oregon,
Washington, Idaho, and Alaska, Pacific Northwest
Indian tribal governments; and U.S. Departments of
State, Commerce, and Interior. Agreements from
the Treaty are assisting in rebuilding depressed
Chinook salmon stocks; in Southeast Alaska,
Chinook catch ceilings provide for hatchery "add-
ons" to allow harvest of salmon from Alaska
hatcheries. 71be Treaty sets catch allocations for
British Columbia sockeye salmon stocks caught in
southern Southeast Alaska traditional net fisheries.
Agreements have been reached on harvest alloca-
tions and bilateral enhancement for transboundary
river sockeye salmon. Pink salmon catch ceilings
have been set to reduce interceptions of Alaska pink
salmon by Canada in boundary fishing areas
between British Columbia and Alaska.

78 Alaska Salmon Resources

25. CHUM SALMON

Chum salmon (Oncorhynchw keta) have
the widest natural geopaphic distribution of CHUM SALMON CATCH
all Pacific salmon species. They range
throughout Alaskan waters from ft Southeast Alaska
Region into the Bering Sea and to northern
Alaska in the Arctic Ocean to the 14ackenzie Millions of fish
River in Canada.
Chum salmon often spawn in large rivers 14-
and stream areas where upwelling ground 7
water is present. In some arm , they can be
found spawning in the same places as pink
10 - . ... ..
7
salmon (0. gorbuscha) including the intertidal
reaches of rivers. Some chum salmon travel
long distances in rivers before spawning. In
the Yukon River, chum salmon may migrate B_
oyer 2,800 km to return to natal spawning
grounds. 4-
In the fall, the female salmon lays up to 2
2,700 eggs in the stream gravel. After
hatching the. following spring, the fry usually 0
move downsawn and by fall have entered the 70 72 74 76 78 80 82 84 86 88 90 92
ocean. 'T'hey remain in the ocean from 2 to Year
4 years feeding in the same areas as salmon
fiom C;anada, Japan, and Russia. Chum Southeast M Central = western
salmon valry in size at maturity and average
about 3-8 kg. Some may weigh as much as
20 kg.
Most chum salmon are caught in near-
shore gill net and purse seine fisheries. Catches target species in CBM BALM=
averaged between 5.4 million and 7.8 million fish net fisheries that Alaska
until the 1980s and were generally incidental to are directed at COMMERCIAL CATCH
pink salmon catches. During the 1980s, market sockeye and pink (1,000s of fish)
demands for chum salmon increased as the avail- salmon and
ability of other salmon decreased and fresh and spawning Ten Year Average
frozen chum salmon from Alasb were marketed in escapement period catch
Japan and northern Europe. The State of AbAn counts are ---------------------
began hatchery production of chum salmon in the generally inexaCL 1890-99 10
1900-09 899
1980s. From 1990 to 1992, about 24% of the catch Stocks in the 1910-19 6,656
in the southeast and central regions has been from western region 1920-29 7,559
hatcheries. may have been 1930-39 7,636
On a statewide basis, chum salmon populations impacted by 1940-49 7,830
1950-59 6,244
am fully utilized but -abundance, as reflected by foreign high-seas 1960-69 5,386
catches, remains well below historic levels. The drftet fisheries 1970-79 6,299
status of the wild stocks is difficult to determine. for squid and 1980-89 11,143
Catch data generally do not reflect abundance of salmon. Large 1990-92 9,214
this species because chum salmon are usually not a numbers of chum
7Fc

M rn

Alaska Salmon Resources 79

salmon were caught, but country-of-origin
data are sparse. These fisheries ended in CHUM SALMON
December 1992 with the United Nations' Alaska
moratorium on pelagic driftnet fishing.
Illegal high-seas fishing in amas where Average catch (1980-92): Alaska = 38,192 t
North American salmon occur remains a Southeast region = 10,771 t
Central region = 13,339 t
concern and has an unknown impact on Western region = 14,082 t
stocks. More research is needed to establish
baseline data so that Pacific Salmon of North Average catch (1990-92): Alaska = 31,668 t
American and Asian origin can be identified Southeast region = 12,537 t
Central region = 7,831t
and to increase understanding of distribution Western region = 11,300 t
and competition with other species in ocean
feeding arm. Long-term potential yield (MSY):
Conservation of some stocks in the Alaska = 38,192 t
Southeast region = 10,771 t
southern southeast region, is a concern where Central region = 13,339 t
lower-thm-average returns to spawning Western region = 14,082 t
areas have been observed and runs have not
rebuilt to historic high levels as have pink Harvesting strategy = Escapement goals
Age/length at recruitment = 3 yrs/55 cm
salmon in the same region. Reasons for the Age/length at 50% maturity = 4-5 yrs/63-71 cm
declines are not fully understood but may be Maximum age = 6 yrs
due to changes in ocean growth and survival, Abundance and trend = Relatively
overharvesting of stocks by coastal fisheries, stable
Importance of recreational fishery = Minor
and degradation in freshwater habitats. Management = State and FMP
Status of exploitation = Fully exploited

Southeast region = east of long. 144* W.
Central region = Prince William Sound, Cook
inlet, Kodiak, and south of Alaska Peninsula.
Western region = north of Alaska Peninsula.

80 Alaska Salmon Resources

26. PINK SALMON

The pink salmon (Oncorhynchm
gorbuscim) is often the "bread and butter"fish PINK SALMON CATCH
in many coastal communities because of their
abundance in much of Alndra Commercially Alaska
important runs of this salmon occur in the
southeast and central regions; Bristol Bay, in 140- Millions of fish
the western region, is the northern limit of
loge runs. This salmon is also popular with 120-
sport fisheries and it is important to subsis-
tence users in Alaska 100-
The pink salmon is the smaUest, of the
Pacific salmon in Alaska Maturing salmon so-
return to spawn in natal streams after
18 months in the ocean (2 years old). A 00-
female lays 1,5@2,000 eggs. Mon spawning
occurs in freshwater streams within a few 40--
miles of the coast and intertidal spawning is
also common. The pink salmon is the only 20 -
Pacific salmon having a fixed 2-year life span
and salmon spawning in odd-numbered years 0.
are reproductively isolated from even-yem TO 72 74 70 78 80 82 44 88 88 90 92
spawning fish. Frequently, in a particular Year
stream. one cycle will dominate over the other.
In other streams, each cycle may have similar Southeast M Contra[ =3 Western
abundance. Soon after emergence, the young
fry migrate to the ocean.
Most pink salmon are caught commercially
in purse seines and gill nets. Historic records
show that catches peaked in the 1930s and 1940s
and then declined to low levels into the 1970s. of wild and Pin SALK=
Alaska
Since 1975, the runs have been rebuilt through hatchery popula- COMMERCIAL CATCH
management efforts, hatchery production, and tions to Prince (1,000s of fish)
favorable ocean survival. Harvest levels peaked in William Sound am
1991 at a record 128 million fislL In 1992, catches not fully under- Ten Year Average
decreased to 00 million fish with reduced returns to stood. LOW period catch
several districts. survival of the ----------------------
Hatchery production in Southeast and Central IM year class 1890-99 1,217
Ala.*a contributes significantly to the total catch. In my be linked to 1900-09 8,338
1910-19 28,293
the 1990-92 period, hatchery-produced pink salmon effiects; of low water 1920-29 36,118
provided 24% of the catch. About 90% of the temperatures on 1930-39 53,960
hatchery produced catch was from Prince William food abundance 1940-49 49,129
Sound. and fry growth and 1950-59 20,880
1960-69 29,840
n
11.1
1"A
W1111111111 I

On a statewide basis, pink salmon populations possible latent 1970-79 26,045
are fully utilize& Most stocb appear to have rebuilt effects from the 1980-89 68,730
to or beyond previous high levels as judged by catch 1989 oil spill in the 1990-92 91,614
datL Reasons for the unexpected low return in I M Sound. There is

Alaska Salmon Resources 81

also concern that decreased spawmng escape-
ments in wild stocks may be due to interactions PINK SALMON
of hatchery releases and returns with wild fish. Alaska

Average catch (1980-92): Alaska = 113,225 t
Southeast region = 48,610 t
Central region = 58,396 t
Western region = 6,218 t

Average catch (1990-92): Alaska = 127,284 t
Southeast region = 57,251 t
Central region = 68,413 t
Western region = 1,621 t

Long-term potential yield (MSY):
Alaska = 113,225 t
Southeast region = 48,610 t
Central region = 58,396 t
western region = 6,218 t

Harvesting strategy = Escapement goals
Age/length at recruitment = 2 years/50-61 cm
Age/length at 50% maturity = 2 years/50-60 cm
Maximum age = 2 years
Abundance and trend = Stable
Importance of recreational fishery = Major
Management = State and FMP
Status of exploitation = Fully exploited

Southeast region = east of long. 144* W.
Central region = Prince William Sound, Cook
Inlet, Kodiak, and south of Alaska Peninsula.
Western region = north of Alaska Peninsula.

82 Alaska Salmon Resources

27. SOCKEYE SALMON

The sockeye or red salmon
(Oncorhynchus nerka) is Alaska's most SOCKEYE SALMON CATCH
valuable salmon. It occurs throughout
much of Alaska and supports commercial Alaska
fisheries in Bristol Bay and Central and Millions of fish
Southeast Alaska
Sockeye salmon spend from 2 to 4 years
in the ocean. Spawning occurs generally in
late summer and fall in freshwater rivers
and lakes. The young Ely normally spend
from I to 2 years in lakes before migrating
in the spring to the ocean. In some stocks.
the firy stay in the rivers only and migrate to
salt water before die first winter.
Most sockeye salmon are caught com-

mercially in nearshore fisheries with gill
nets and purse seines. Except for a small
percentage of sockeye salmon caught in the
EEZ all fisheries occur in state waters and
the resource is managed by the ADF&G. In
Southeast Alaska sockeye salmon fisheries 70 72 74 76 78 80 82 84 86 88 90 92
Dear transboundary rivers and the U.S.- Year
Canada, border am managed in compliance
with the Pacific Salmon Treaty between the Southeast Central Western
United States and Canada. Sockeye salmon
from British Columbia occur in varying
numbers each year in Southeast Alaska
waters where some are caught in U.S. fisheries.
The area with the largest production of sockeye the Cook Inlet and SOCKEYE SALMON
salmon is Bristol Bay in the western region. In Kodiak Island Alaska
recent years, about 60% of the total catch in the state areas. COMMERCIAL CATCH
has come from Bristol Bay. Stocks in the (1,000s of fish)
Sockeye salmon catches were low in the mid- three regions are
1970s, but subsequently increased and reached a fully utilized. most Ten Year Average
high of 52.7 million fish in 1983 as stocks rebuilt. stocks appear to be period catch
The IM catch of 583 million fish is an all-time rebuilt from ----------------------
record. The recent 1990-92 average catch was previous low levels 1890-99 1,479
52.0 million fish. Sockeye salmon from hatcheries and are productive 1900-09 20,853
1910-19 26,826
and lake stockings are now a significant part of with recent yields 1920-29 23,679
catches in some areas. Returns from enhancement at or above 13-year 1930-39 25,321
projects in the southeast and central regions made up average& Near- 1940-49 17,230
about 12% of the catch in 1992. From 1990 to 1992, record catches in 1950-59 10,990
1960-69 13,230
the avenge contribution from enhancement to 1992 were recorded 1970-79 13,626
commercial catches was 20%. Much of the en- in Bristol Bay and 1980-89 37,094
hanced production is from returns to hatcheries in off Kodiak Island 1990-92 52,021

Alaska Salmon Resources 83

while man y other areas had above-average
catches. One area with lower than average SOCXM SALMON
returns of wild stocks has been Prince William Alaska
Sound.

Average catch (1980-92): Alaska = 109,025 t
Southeast region = 4,692 t
Central region = 30,731 t
Western region = 73,602 t

Average catch (1990-92): Alaska - 138,885 t
Southeast region = 6,348 t
Central region = 40,512 t
Western region = 92,025 t

Long-term potential yield (MSY):
Alaska = 109,025 t
southeast region = 4,692 t
Central region = 30,731 t
Western region = 73,602 t

Harvesting strategy = Escapement goals
Age/length at recruitment = 4 years/50 cm
Age/length at 50% maturity = 5 years/60-70 cm
Maximum age = 6 years
Abundance and trend = Stable
Importance of recreational fishery = Minor
Management = State and FMP
Status of exploitation = Fully exploited

Southeast region = east of long. 144* W.
Central region = Prince William Sound, Cook
Inlet, Kodiak, and south of Alaska Peninsula.
.Western region = north of Alaska Peninsula.

84 Alaska Salmon Resources

28, COHO SALMON

Coho Salmon (Oncorhynchus kisutch),
the third largest spmes of Pacific salmon, COHO SALMON CATCH
are found dmughout Alaska The species is Alaska
most abundant in the central and southeast
regions of the sm. Maturing coho salmon Millions of fish
enter fresh water from August through
November to spawn in a myriad of small
Streams as well as Inc rivers. Spawrting
typically takes place in Alaska from late
September through January when females
deposit from 2AW to 4,500 eggs. The
juveniles spend one, two, or three winters in
fresh water and then migrate to the ocean to 4
spend about 18 months before returning to
their freshwater stream of origin.
Troll and net fisheries for coho salmon in
Alsi-ka now land over 5 million fish annu-
ally. Coho salmon are also an important
sport fish in marine and fresh water with
about 300,000 fish taken each year. Catches 0-
have increased greatly since the mid-1970s. 70 72 74 76 78 80 82 84 86 88 90 92
In 1975, the statewide harvest was about Year
I million fish; since 1980, catches have
ranged from 3.1 to 7.0 million fish. About Southeast M Central western
5% of the catch is currently from the EEZ
troll fishene& Management is conducted by
the State of Alaska in nearshore waters and
by the NMFS in the EEZ. Coho salmon from
hatcheries and lake stockings made up about 14% of driftnet fishing, WHO SALUM
the 1990-1992 catch in the southeast and central but illegal fishing Alaska
regions. Since 1986,-enhanceinent has produced 8- continues in areas COMMERCIAL CATCH
179b of the catches in the two regions. where North (1,000s of fish)
The status of coho salmon stocks in the state is Amenqm salmon
apparently good when judged by recent catch levels. feed. The full Ten Year Average
All stocks appear to be fully utilized and in most impact of Woo period catch
management arm, the stocks yield good catches. high-sm fishing ----------------------
Status of stocks remains difficult to assess because it on coho salmon 1890-99 380
1900-09 659
is difficult to identify individual populations in will be unknown 1910-19 1,620
catches and viirtually impossible to detemme until mom infor- 1920-29 2,120
spawning escapements of coho salmon in the mation is obtained 1930-39 2,360
of spawning arm. on stock identifica- 1940-49 3,099
1950-59 2,091
Them is concern that some stocks may have been tion, ocean 1960-69. 1,856
impacted by foreign high-seas pelagic driftnet distributions, and 1970-79 1,837
fishmg Jin ocean areas where North Ammm coho feeding arm. 1980-89 4,595
Salmon mix with salmon from Asia. A 1992 United Other activities 1990-92 5,653
Nations resolution now bans pelagic high sm mayimpact

Alaska Salmon Resources 85

spawning and rearing habitat of coho
salmon. Large areas of Alaska's wetlands COHO S&MON
are Presently undisturbed and pristine and Alaska
Provide habitat critical to anadromous
fishes. Concerns exist in some areas over Average catch (1980- 192): Alaska = 16,069 t
loss of Ereshwater habitat. In the southeast Southeast region = 6,679 t
region, logging in the Tongass National Central region = 5,545 t
Forest and on state and native lands has Western region = 3,844 t
impacW coho salmon habitat. Greater Average catch (1990-92): Alaska = 17,829 t
protection to salmon habitat is offered by Southeast region = 8,337 t
recent legislation that requires that stream- Central region = 5,501 t
sides be protected and that buffer strips of Western region = 3,991 t
standing timber be left along streams to Long-term potential yield (MSY):
protect spawning and rearing habitats. Alaska = 16,069 t
Southeast region = 6,679 t
Central region = 5,545 t
Western region = 3,844 t

Harvesting strategy = Historical catch
Age/length at recruitment = 3 years/55 cm
Age/length at 50% maturity = 4 years/74 cm
Maximum age = 5 years
Abundance and trend = Stable
Importance of recreational fishery = Major
Management = State and FMP
Status of exploitation = Fully exploited

Southeast region = east of long. 144* W.
Central region = Prince William Sound, Cook
Inlet, Kodiak, and south of Alaska Peninsula.
Western region = north of Alaska Peninsula.

86 Alaska Salmon Resources

29, CHINOOK SALMON

The chinook or king salmon
(Oncorhynchus tshawytscha) is the largest of
the ftcific salmon with some adults reach- CHINOOK SALMON CATCH
ing a weight of 45 kg. Chinook salmon are Alaska
found throughout most of Alaska hUjor
populations return to the Yukon, 1000- Thousands of fish
Kuskokwim, Nushagak, Susitna, Kenai,
Copper, Alsek, Taku, and Stikine Rivers.
Important runs also origin= from numerous 800--
smalterrivers.
Alaska rivers normally have a single run
of spawning chmook salmon which lasts 600-
from May through July. Adults return to
Eresh water after 2 to 5 years. Females
400-
deposit Erom 3,000 to 14,000 eggs which
hatch in late winter or early spring. Most
juvenile chinook salmon remain in fresh 200-
water until the spring following hatching
and then migrate to the ocean,
Chinook salmon migmte long distances 0 -
in the North Pacific Ocean. Salmon caught 70 72 74 76 78 80 82 84 Be so 90 92
in the southeast and central regions of the Year
Gulf of Alaska am from natural spawning
and hatchery production facilities in Alaska, Southeast M central M Western
British Columbia, Washington, and Oregon.
The many fisheries and stocks along the
coast from the Pacific Northwest to South-
east Alaska are managed to rebuild stocks
under terms of the Pacific Salmon Treaty. Recent ment is directed at
data show that some indicator stocks of chinook achieving escape- CEMOCK
salmon in the Treaty area are not responding to ment goals, Alaska
rebuilding efforts. Stocks of concern in Southeast reducing inciden- COMMERCIAL CATCH
Alaska include those in Behm Canal and the tal harvests, and (1,000s of fish)
traiisboundary rivers. increasing
Most commercial catches are made by troll and production Ten Year Average
gill-net fisheries on mixed stocks in nearshore areas. through enhance- period catch
----------------------
Total statewide catch has averaged about 684,OW ment. Recent 1890-99 47
fish annually between 1980 and IM. This catch decreases in 1900-09 207
includes about 80,OW Chinook salmon produced by harvests in the 1910-19 528
hatcheries in Southeast and Central Ahaska- The western region 1920-29 738
1930-39 766
chinook salmon in Alsksksk is highly prized world- rcflect weaker 1940-49 654
wide by sport fishers who travel to Alaska seeking returns to Bristol 1950-59 616
wild am fishing experiences. About 134,WO Bay and the 1960-69 556
chinook salmon am caught annually in the sport Lower Yukon 1970-79 617
1980-89 694
fisheries. River arm. In 1990-92 625
AD stocks in Alaska are fully utilized. Manage- Bristol Bay, the

Alaska Salmon Resources 87
r-T
F

1991 return was below average for the sixth con- Dahlberg, M. L. 1990. The high seas salmon
secutive year. fisheries of Japan, 1989. Alaska's Wildlife,
Some Alaska stocks may have been reduced by ADF&G, 22(4):25-26,40-41.
foreign high-seas pelagic driftnet and trawl fishing.
International agreements now restrict or limit high- Eggers, D. M. [editor] 1989. Alaska commercial
seas fisheries in ocean areas where North American salmon catches, 1878-1988. Alaska Dep. of Fish and
chinook salmon occur, but illegal fishing stW Game, Regional Info. Rep. No. 5J89-04, 69 p.
remains a concern. High-seas catch data remain
incomplete and more research is needed to establish Geiger, H. J., and H. Savikko. 1991. Preliminary
baseline data so that Pacific salmon of North forecasts and projections for 1991 Alaska salmon
American and Asian origin can be identified and fisheries and summary of the 1990 season. Alaska
their ocean distribution determined. In U.S. Dep. of Fish and Game, Regional Info. Rep. No.
groundfish fisheries, some chinook salmon are taken 5J91-01, 70 p.
incidentally in the Bering Sea, Gulf of Alaska and
off the Pacific CoasL The NPFMC continues to Geiger, H. J., and H. Savikko. 1992. Preliminary
work with the U.S. industry to reduce chinook forecasts and projections for 1992 Alaska salmon
salmon bycatches. fisheries and review of the 1991 season. Alaska Dep.
of Fish and Game, Regional Info. Rep. No. 5J92-05,
For further information 74 p.

Benton, D. 1990. Alaska and the fisheries of the Groot@ C., and L. Margolis [editors]. 199 1. Pacific
North Pacific and Bering Sea. Alaska's Wildlife, salmon life histories. UBC Press, Vancouver, B.C.,
ADF&G, 22(4):13-23. 564 p.

88 Alaska Salmon Resources

McNair, M., and J.S. Holland. c=OOX SAIXON
Alaska
1993. FRED 1992 annual report
to the Alaska State Legislature. Average catch (1980-92): Alaska = 5,668 t
Alaska Dep. of Fish and Game, Southeast region = 2,031 t
Annual Rep. No. 127, Central region = 805t
102 p. Western region = 2,832 t

McPhail, J. D., and C. C. Average catch (1990-92): Alaska = 4,830 t
Southeast region - 2,179 t
Lindsey. 1970. Freshwater fishes Central region - 750t
of northwestern Canada and Western region = 1,901 t
Alaska. Fish. Res. Board Can.,
Bull. 173, 381 p. Long-term potential yield (MSY):
Alaska. - 5,668 t
Southeast region = 2,031 t
Meehan, W.R. [editor]. 1991. Central region = 805t
Influences of forest and rangeland Western region = 2,832 t
management on salmonid fishes Harvesting strategy = Catch ceilings
and their habitats. American Age/length at recruitment = 4 years/60 cm
Fisheries Society Special Publica- Age/length at 50% maturity = 5-6 years/60-90 cm
tion 19, 51p. Maximum age = 7 years
Abundance and trend - Relatively stable
Importance of recreational fishery = Major
North Pacific Fishery Manage- Management = State, FMP, Prohibited
ment Council. 1990. Fishery species catch amount
management plan for the salmon (Groundfish FMPs)
fisheries in the EM off the coast Status of exploitation - Fully exploited
of A laqka. N. Pac. Fish. Manag.
Council, P. 0. Box 1031316, Southeast region = east of long. 144* W.
Anchorage, Alaska 99510. Central region = Prince William Sound, Cook
Inlet, Kodiak, and south of Alaska Peninsula.
Western region = north of Alaska Peninsula.

Alaska Salmon Resources 89

MARINE MAMMALS
By Howard W. Braham

@N
o
;t

Illustradw: Katwine Zooca

This section of the report presents information on calf-rearing seasons in higher latitudes.
selected marine mammals off Alaska. Forty two IMere are several populations of marine mam-
species of marine mammals in U.S. waters of the mals that only spend a portion of the year in Alaska
North Pacific Ocean are under the jurisdiction of the waters, such as humpback whales and northern fur
Department of Commerce. This includes 31 species seals, whereas others are found year-round in
of whales, dolphins and porpoises, and 11 species of Alaska, such as the bowhead whale. These zoogeo-
seals and sea lions. Most marine mammals make graphic differences have led to varying life history
long-distance migrations or move hundreds of miles strategies and result in the need to manage several
within smaller areas of the ocean between seasons of populations or stocks rather than just one. Manage-
the year. Whales and dolphins often travel from one ment of marine mammals is carried out under the
feeding ground to another or to spend the breeding Marine Mammal Protection Act (NIMPA) of 1972
season in lower latitudes and the major feeding and and the Endangered Species Act (ESA) of 1973.

Marine Mammals 91

STATUS OF RESIDENT AND SELECTED SPECIES
OF MARINE MAMMALS
OFF ALASKA I
(e)=endangered; (Q--threatened; (d)--depleted

Species Abundance Trends Method of Assessment Status and
(954 C.I.) (+/-%) Assessment Coverage Authority
------------------------------------------------------------------------------------------------------
Bowhead 7,500 +3.1/yr Ice-based Complete Below OSP
whale (6,400-9,200) (1978-88) counts ESA (a)

Gray whale 20,869 +3.3'b/yr Land-based Complete Recovered
(19,200-22,700) (1968-88) counts ESA W

Humpback >2,000 Unknown Photographic Partial Below OSP
whales mark-recap. ESA (a)

Killer whale >300 Unknown Individual Partial Uncertain
counts MWA

Beluga 15,800-18,450 Unknown Aerial and Partial Uncertain
land-counts HMPA

Dell's 300,000-600,000 Unknown Line transect Partial Uncertain
porpoise MMPA

Harbor Unknown Unknown Uncertain
porpoise MMPA

Northern >34,844 -70% Counts on Complete Below OSP
sea lion (1970-90) shore ESA (t)

Northern 982,000 -504 Land-counts Complete Below OSP
fur seal (1975-90) Pribilof Is. MWA (d)

Harbor seal Uncertain -60* Land-counts Partial Below OSP
(<100,000) (1976-92) Tugidak Is. MMPA

Spotted2 Unknown Unknown Ice-counts and Partial Uncertain
seal land counts

Bowhead, gray and humpback whale estimates are for the entire eastern North Pacific Ocean;
all others are for Alaska.
Other ice-associated seals are the bearded, ribbon, and ringed seals.

Both Acts require that management of Incidental Take of Selected Marine Mammals
marine mammals be based on the In Domestic Fisheries
identification and enumeration of off Alaska
populations
or stocks. Species Incidental Take Fishery 10-year Trend Impact of
A summary of the status, impact of (others) Exploitation
incidental take, and desciption of ;;-a-y w--h-a-l-e ------- U-n-k-n-o-w-n ----- C_o_a_zra__1__3_et__-n_e_r_3 -------- U-n-k-n-o-wn ---- Un__c_h_an__9e__d
selected stocks is described in the Killer whale Unknown Long-line and Unknown Unknown
following chapters. gill-nets
Beluga whale Unknown Coastal gill-nets Increasing? Unknown

Dall13 porpoise Unknown Coastal gill-net3 Unknown Unknown
Harbor porpoise Unknown Coastal gill-nets Unknown Unknown

Northern 1,023/yr (1978-85) Coastal gill- Decreasing Unknown
sea lion <100/yr (1988-92) nets and trawls

Northern Three(1990) Coastal gill- Decreasing Unknown
fur seal nets and trawls

Harbor seal Unknown Coastal gill- Unknown Unknown
nets and trawls
Spotted seal Unknown Unknown Unknown Unknown

92 Marine Mammals

30. BOWHEAD WHALE

The bowhead whale (Balaena Bowhead Whale
mysticew) also known as Agvik by Western Arctic
Alaskan Eskimos, is the only large
cetacean associated with the Arctic Whales (Thousands of Individuals)
pack-ice year round. The species is 6000-
endemic to the Northern Hemisphere 5000
with three stocks in the North
Atlantic Ocem (East Greenland- 4000
Spitsbergen, Baffin Bay-Davis SL,
and Hudson Bay-Foxe Basin) and 3000--
two stocks in the North Pacific
(Okhotsk Sea and western North 2000-
American Arctic).
The migration of bowheads in 1000-
western Arctic Alaska takes place
from late March through June from 0-
the western Bering Sea (Russia) into 78 79 80 81 82 83 84 85 86 87 88
the Beaufort Sea (U.S. and Canada). Year
Some remain in the Chukchi Sea
during summer. The autumn migration precedes the NMFS was initiated in 1978 by agreement with the
advancing pack-ice from September to December. International Whaling Commission.
Calves are born from March to July, following a The present estimate of abundance of the western
13-month gestation period. Pregnancy rates vary Arctic stock is 7,500 (95% C.I., 6,400-9,200) based
from 0.15 to 0.33; the calving interval is 4-5 years. on a combined analysis of ice-based observer counts
Length at birth is 4-5m, 8-9m at age 1. and 13-14m and passive acoustics data collected off Point
at sexual maturity (females). Age at first reproduc- Barrow, Mmksi, during the bowhead's spring
tion is thought to range from 9 to 15 years. Annual migration. Changes in estimates of abundance since
calf production varies from 3% to 12%, possibly census studies began in 1978 reflect improvements
reflecting an unstable or highly variable ecosystem. in the methods of data collection and analysis, and
Euphausfids and copepods are the principal prey, but in an actual increase in the number of whales. Since
epibenthic fauna are also taken. - 1978, this bowhead stock has increased 3.1% (95%
Bowhead whales were one of the most severely Cl., 0.1-6.2) per year based on counts of whales
exploited cetaceans: in the history of commercial adjusted for periods of no-watch and bad weather.
whaling. The world abundance prior to commercial Additional simulations also show that the stock has
whaling probably exceeded 120,000, but at its lowest increased since 1920, just after commercial whaling
point, near the beginning of the 20th century, the ended. The present size of the stock is about 40.9%
species totaled no more than a few thousand. In the (95% C.I., 38-42) of its initial size (in 1848) based
western North American Arctic, 18,650 bowheads on simulation and sensitivity tests of historic data.
were killed by Yankee whalers between 1848 and These data suggest that the western Arctic stock of
1914 -- this from a population of probably less than bowheads is recovering from commercial whaling
18,000-20,000 animals; over 60% of the whales were and that it is below the population size supportable
killed between 1850 and 1870. Alaskan Eskimos by the ecosystem (ie., its carrying capacity).
(Inuit) have used bowhead whales for subsistence for Critical habitat may include the spring open lead
several thousand years. This century the take of system from the Bering Strait to the Beaufort Sea,
bowheads at U.S. coastal Imlit v@llages averaged 20 the nearshore Beaufort Sea in autumn for feeding
whales killed per year Erom 1920 to 1969, about 40 and migration, and polynya and other open-water
per year from 1970 to 1977, and 22 per year between areas within the Bering Sea pack-ice used by
1978 and 1990. A quota system administered by the bowheads to overwinter.
Alaskan Eskimo Whaling Commission and the

Marine Mammals 93

For further information
Take of Dowhead. Whales
Bockstoce, J. P, 1986. Whales, ice, and men. by Alaskan Zsk4 a, 1978-1990
The history of whaling in the western Arctic. ---- Pate of Whales ----
Univ. Washington Press, Seattle, WA- 400p. Year Ouota Struck Landed Killed'
Braham, H. W. 1989. Eskimos, Yankees, and ---------------------------------------------
1978 20 18 12 16
bowheads. Oceanus 32(l):54-62. 1979 27 27 12 i3
1980 26 34 16 29
Breiwick, J. M., L. L. Eberhardt@ and H. W. 1981 32 28 17 26
Braham. 1984. Population dynamics of western 1982 19 19 8 13
1983 is 18 10 16
arctic bowhead whales (Balaena mysticetus). 1984 25 25 12 22
Can. J. Fish. Aquatic Sci. 41: 4844%. 1985 18 17 ft 13
1986 32 28 20 23
Krogman, B., D. Rugh, R. Sonntag, J. Zeh, and 1987 32 31 22 29
1988 35 28 15 28
D. Ko. 1989. Ice-based census of bowhead 1989 44 26 .18 18+
whales migrating past Point Barrow, Alaska 1990 44 44 30 30+
1978-83. Mar. Mammal Sci. 5: 116-138.
Nerini, M. K., IL W. Braham, W. M. Marquette, An estimate of the fate of whales struck and
lost is reported to NMFS by the Alaskan
and D. J. Rugh. 1984. Life history of the Eskimo Whaling Commission; a *+' means that
bowhead whale, Balaena mysticetus the number killed, beyond the number landed,
(Marnmalix Cetacea). J. Zool. (London) 204: is unknown.
443468.

Zeh, 1. E., 1. C. George, A. I- Raftery, and G. M.
Carroll. 199 1. Rate of increase, 1978-1988, of
bowhead whales, Baldena mysticetus, estimated
form ice-based census data. Mar. Mammal Sci. 7:
105-122.

94 Marine Mammals

31, GRAY WHALE

There are two stocks of gray whales December to early February. There is some overlap
(Eschrichtius robustus) endemic to the North Pacific with the first of the northward migrants from Baja
Ocean. One stock is located in the eastern North California with the taff-end of the migration moving
Pacific Ocean, the stock migrates between the south. A small number of whales do not undertake a
western Arctic Ocean (off the U.S., Canada, and full migration and spend the winter in waters south
Russia coasts) to waters off Baja California. Ile of Alaska.
second stock migrates from the Okhotsk Sea along Gray whales are generally dark gray to black in
the coast of Russia, Japan, Republic of China, and color with mottled patches of white generally formed
the Republic of Korm The eastern North Pacific or from the sloughing of ectoparasitic barnacles such as
"CalifoniW' stock was heavily exploited, principally Cyamus scammoni. As with other baleen whales,
by Yankee commercial whalers during the second adult female gray whales reach sexual maturity at
half of the. 19th century, and may have been reduced slightly greater lengths (12.95 m, standard error
to only a small Eraction of its pre-exploitation (SE) = 0.11) than do males (12.43 m, SE = 0.12),
population size. with maximum physical maturity reached at ap-
Gray whales in the eastern North Pacific Ocean proximately 14.0 m in females and 13.0 m in males
are distributed across much of the southern Chukchi at perhaps 40 years of age. Mean birth length is
and northern Bering Seas where they feed from May 4.6 m (both sexes), 7-8 m at weaning (usually 6-8
to November. They migrate out of the Bering Sea by months postpartum) and at I year the young animal
December. Southward migrating gray whales are is 8 m or greater. Age at sexual maturity is
found along the west coast of North America from 9 years (range 6-12 years) for females and 6 years
November to February with the majority of the (range 5-9 years) for males' ' Mean conception date is
whales passing central California from early 5 December, mean birth date is 27 January; and

Marine Mammals 95

gestation lasts 418 days, on average.
With an ovulation rate of 0.50/year Gray Whale
and a pregnancy rate of 0.46/year, an Eastern North Pacific
adult female gray whale gives birth Annual abundance (in thOUSS@Cls)
about every 2 years. Estimated 25-
survival rates range from 95% for
adults to 89% for juveniles. 20-
The present size of the eastern
North Pacific stock of gray whales is
20,869 (19,MO-22,700). This level 15-
is equal to or larger than the size of
the population in 1846, estimated to 10-
have been 15,000-20,000. The
population has been increasing at a 5-
rate of 33% per year (SE = 0.5%)
since 1968, during which a subsis-
tence catch of 167 whales per year 0 68 70 72 74 76 718 8.0 82 84 86 88 90
(SE = 3.5) took place by the Soviet
Union.

For further information

Braham, H. W. 1984. Distribution and migration of
gray whales in Alaska, p. 249-266. la M.L. Jones,
S. L. Swartz, and S. Leatherwood (eds.), The Gray
whale, Eschrichtius robustus. Orlando, FL. Aca-
demic Press, Inc.

Braham, H. W., and G. P. Donovan (eds.). In press.
The comprehensive assessment of gray whales,
Eschrichtius robustus. Cambridge, U.K., Interna-
tional Wbaling Commission (Special Issue 14).

Reilly, S. B., D. W. Rice and A. A. Wolman. 1983.
Population assessment of the gray whale,
Eschrichtius robustus, from California shore
censuses, 1967-1980. Fish. Bull., U.S. 81: 267-281.

Rice, D. W., and A. A- Wolman. 197 1. The life
history of the gray whale Eschrichtius robustus.
Special Publication, Amer. Soc. Mammal. 3: 1-142.

Rugh, D., R. Ferrero, and M. Dahlheim. 1990.
Interobserver count discrepancies in a shore-based
census of gray whales. Mar. Mammal Sci. 6(2):
109-120.

96 Marine Mammals

32. HUMPBACK WHALE

qw- low

Photo: AFSC

Humpback whales (Megaptera novaeangliae) Alaska at any time of year, especially in Southeast
occur in all oceans of the world. Like most baleen Alqqkq but there is no evidence to suggest that any
whales, humpbacks annually migrate to high- of those individuals regularly overwinter there.
latitude, summer feeding grounds firom temperate or Short-term seasonal distribution patterns have been
sub-tropical wintering grounds. The North Pacific documented in Southeast Alaska and in Prince
humpback whale population tentatively has been William Sound, including fairly predictable local
divided into three stocks, based on the relative movements, such as those among favored feeding
discreetness of wintering areas: 1) the Mexican areas. Seasonal distribution of humpbacks on the
stock, 2) the Hawaiian stock, and 3) the Asian stock feeding grounds is subject to annual variability due
(near the Bonin and Ryukyu Islands, Japan). Some to changes in oceanographic conditions and the
exchange takes place between the Mexican and distribution and availability of prey.
Hawaiian stocks, which can be found in summer in The pre-exploitation (prior to 1905) population
California, southeast Alaska, and the Gulf of Alaska. size of humpback whales in the North Pacific Ocean
The wintering grounds of humpbacks seen in the (western and eastern stocks) is not known, but
Bering and Chukchi seas is unknown, although a estimates suggest that it may have been on the order
small number of whales tagged in the western North of 15,000 whales. There has been no sequence of
Pacific Ocean south of Japan in the 1950s and 1960s surveys long enough or consistent enough to detect
were recovered near the eastern Aleutian Islands a trends in abundance.
few years after taggirig. Current estimates of population size range Erom
Humpbacks primarily inhabit Alaska waters from about 1,200 to over 2,000. More than 1,000 whales
late spring to early winter, approximately May have been identified in Hawaii (between 1977 and
through December. Peak numbers of whales off 1982). Mark-recapture analyses based on photo-
Southeast Alaska typically occur in late August and identification data suggest that 1,600 - 2,100 whales
September. Individual humpbacks may be seen in annually visited Hawaiian waters (during the 1970s

Marine Mammals 97

and 1980s). No good estimates are available for the For further information
number of whales on the other wintering grounds in
Mexico or the western Pacific. Preliminary work Baker, C. S., S, R. Palumbi, H. Lambertson, M. S.
suggests there may be only a few hundred hump- Weinrich, J. Calambokidis, and S. J. O'Brien. 1990.
backs outside the main Hawaiian breeding grounds. Influence of seasonal migration on the geographic
The current best estimate for the eastern North distribution of mitochondrial DNA haplotypes in
Pacific stock(s) is 1,398-2,040. This population size humpback whales. Nature 344:238-240.
is only 8%-13% of its estimated initial size of 15,000
in the North Pacific in 1850 prior to commercial Baker, C. S., and L. M. Herman. 1987. Alternative
whaling. population estimates of humpback whales
An estimated 300 to 350 humpbacks are present (Megaptera novaeangliae) in Hawaiian waters.
in Southeast Alaska during summer and fall. Aerial Can. J. Zool. 65: 2818-282 1.
and shipboard survey data have been used to
estimate that about 400 humpbacks summer in the Baker, C. S., L. M. Herman, A. Perry, W. S. Lawton,
Gulf of Alaska and Prince William Sound and J. M. Straley, and J. H. Straley. 1985. Population
another 300 to 350 may summer near the Shumagin characteristics and migration of summer and late-
and Semidi Islands, Alaska. The number of hump- season humpback whales (Megaptera novaeangliae)
backs near the eastern Aleutian Islands is unknown in southeastern Alaska. Mar. Mammal Sci. 1: 304-
but presumably small. Less than 100 sightings of 323.
humpback whales have been made in the Bering Sea
since 1975. Hammond, P. S., S. A. Mizroch, and G. P. Donovan
There are few reported fishery interactions with (editors). 1990. Individual recognition of cetaceans:
humpback whales, such as incidental take, in Use of photo identification and other techniques to
Alaska. Three humpbacks were reported to be estimate population parameters. Cambridge, U.K.,
entangled in seine nets in Prince William Sound in Int. Whaling Comm. (Special Issue 12), 440 p.
the early 1980s. T@pically two or dim humpbacks
are reported entangled each year in gill nets and Humpback Whale Recovery Team. 1990. National
buoy lines in Southeast Alaska and British Colum- recovery plan for the humpback whale (Megaptera
bia. In the summer of 1987 at least seven hump- novaeangliae) in waters of the United States of
backs were reported entangled in gill nets in America. U.S. Department of Commerce, NOAA,
Southeast Alaska;- only one whale died. No esti- NMFS, Washington, D.C., 82 p. (Available through
mates are available for the extent of unreported the Office of Protected Resources, NMFS, NOAA,
incidental take, nor are estimates available for the 1335 East-West Highway, Silver Spring, MD
incidental take of humpbacks by commercial 20910.)
fisheries in other areas of Alaska.

98 Marine Mammals

33. KILLER WHALE

The killer whale (Orcinus orca) is the largest been subjected to significant rates of exploitation and
member of the dolphin family Delphinidae. The are not taken for subsistence. Incidental takes
large size, distinct dorsal fin, contrasting white and during fishing operations are rare. Significant
black coloring, robust body, postocula white patch, fishery interactions have been docurnented between
and ovate flippers are diagnostics. Adults range in killer whales and sablefish in the Bering Sea and
length from 5 to 9 in. Dorsal fin height can be Prince William Sound. Between 1985 and 1987, 7
1.8 in in adult males and up to 0.9 in in adult females killer whales from a resident pod of 35 were ob-
and sub-adult males. The genus Orcinus is consid- served taking sablefish off fisherman's longlines.
ered monotypic with geographical variation noted in The seven were later reported missing and are
size and coloring. Differences in call repertoires and presumed to be dead. Fishermen sometimes shoot at
overlapping color patterns indicate some isolation killer whales and use seal bombs and other explo-
among pods. Chromosomal and biochemical sives to keep the whales away from their catch.
evidence suggests that certain pods may be gened- There is no estimate of abundance of killer whales in
cally distinct. Alaska. The total population size is probably not
Killer whales have been observed in all oceans large, based on anecdotal accounts during surveys
and seas of the world and, although reported from for other species. The total estimate of abundance
tropical and off-shore waters, they prefer the colder for Prince William Sound, Shelikof Strait and
waters typically within 800 Ian of major continents. Southeast Alaska is 286. Population estimates are
In Alaskan waters, they concentrate near land not available for the western Gulf of Alaska- Aleu-
masses and continental shelf waters and are found in tian Islands, or Bering Sea and north.
greatest numbers in Southeast Alaska, Prince
William Sound, near Kodiak Island, and in the For further information
southeastern Bering Sea. They also have been seen
as far north as the Arctic Ocean. Braharn, H. W., and M. E. Dahlheim. 1982. Killer
Killer whales typically occur in small pods of whales in Alaska documented in the Platforms of
fewer than 40 animals. Multi-pod gatherings have Opportunity Program. Rep. Int. Whaling Comm.
been noted, however, the biological significance of 32:643-646.
these groupings is not known. Pod composition
appears to remain constant for many years with little Dahlheim, M. E. 198 1. A review of the biology and
intermixing of individuals among pods. At least two exploitation of the killer whale, Orcinus orca, with
major types of pods have been noted. Transient pods comments on recent sightings from Antarctica. Rep.
move in and out of areas typically occupied by Int. Whaling Comm. 31: 541-456.
resident pods of killer whales, but have no defined
"home range." Resident pods are usually found in Dahlheim, M. E. 1988. Killer whale (Orcinus orca)
one area year-round (encompassing several hundred predation of longline catches of sablefish
to several thousand square miles), and are dominated (Anoploponuifintbria) in Alaskan waters. NWAFC
by strong matriarchal lineages. The natural mortal- Processed Rep. 88-14, 31 p. Alaska Fish. Sc. Cent.,
ity rate of killer whales is estimated to be less than Nal. Mar. Fish. Serv., NOAA, 7600 Sand Point Way
5% per year, and may be as low as 1% per year, NE, Seattle, WA 98115.
suggesting that killer whales form stable and long
lasting family units. Dahlheim, M. E., and J. Heyning. In press. The
Movements of killer whales are believed to be killer whale. In S. Ridgway and R. Harrison (eds.),
related to the availability of prey, such as spawning Handbook of Marine Mammals. New York, NY,
Pacific salmon, and the movements of seals and Academic Press.
whales. Killer whales prey on cod, herring, flatfish,
sablefish, and other fish. Resident pods typically
prey on fish, and transient pods possibly favor
marine mammals as prey. Killer whales have never

Marine Mammals 99

34. BELUGA WHALE

In western North America, beluga whales ruled OUL Lactation Can vary from 12 to 32 months,
(Delphinapterus leucas), also known as belukha or but appears to last on average between 1 and 2 years.
white whales, are located in coastal waters of Alaska The minimum estimated total population in
from the eastern Gulf of Alasksk near Yakutat Bay Alskskn waters is 15,800 to 18,450 including about
north into the Beaufort Sea. Based on the potential 400-500 in the Gulf of Alaska-Cook InIeL Some
for geographic isolation as a result of differential estimates are as high as 30,000 to account for
seasonal movements versus year-round residency, animals offshore or not observed during past surveys.
there are possibly four (summer) stocks. 'Me stocks Beluga whales are taken incidentally in commercial
are located in 1) Cook Inlet (north Gulf of Ahtska); and native coastal fisheries in Alaska and for
2) Bristol/Kuskokwim Bays and Norton Sound/ subsistence. Most incidental kills occur in Bristol
Yukon Delta (Bering Sea); 3) Kotzebue Sound and Bay where a large salmon fishery exists. In 1983,
west coast of the Chukchi Sea; and 4) the eastern 27-31 belugas were found dead in Bristol Bay and 12
Beaufort Sea. were caught in salmon gill nets. Up to five belugas
North of lat. W N, belugas are closely associated per year have been reported taken in the salmon
with open leads and polynya in ice-covered regions. gillnet fishery in Cook Inlet.
Concentrations occur in both offshore and coastal Only indigenous people are allowed to hunt
a= , which vary by season and region. Factors belugas. Subsistence takes occur in western Alaska
affecting seasonal and daily distribution include (especially in the northern Bering Sea and Chukchi
extent of ice cover, prey availability, tidal conditions, Sea), along the Russian Far East of Chukotka, and in
and human disturbance. Generally, beluga whales the western Canadian Arctic Ocean (eastern Beau-
occupy waters associated with offshore pack-ice in fort Sea). The estimated total kill (landed, stuckor
winter, and migrate in spring to warmer (100-150C) lost) in U.S. waters and the Canadian Beaufort Sea
coastal estuaries, bays, and rivers to molt and to rear exceeds more than 800 per year (based on data from
calves. Most of the North American population in the 1970s and 1980s), although the precise annual
Alaska waters is associated with the offshore winter total is unknown. These.animals probably come
areas, although year-round concentrations occur in from the same population that winters in the Soviet
the Bering Strait, the southern Chukchi Sea, Bristol and U.S. Bering Sea. Ile actual number of animals
Bay, and in Cook Inlet. killed each year is not known because most of the
The duration of residence in summer coastal villages are not monitored, and the fraction of
areas varies from a few days to several months, and whales that die after being stuck is also unknown.
most belugas usually remain in densely concentrated The number of belugas incidentally killed and
groups throughout summer. Migration to coastal harvested is probably not great enough to affect the
areas coincides with the break-up of ice and the total population, but the affect on local stocks is
arrival of spawning fish such as Arctic cod unknown (800 is 5% of the minimum total popula-
(Boregadus saida), smelt, herring, capelin (Mallotus tion estimate of 15,800).
villosus), and Pacific salmon. Belugas make use of
tides in pursuit of prey by ascending rivers on the For further information
flood and descending with ebb tides; a few have been
sighted 1,000 Ian up the Yukon River. Braham, H. W., B. D. Krogman, and G. Carroll.
Calving occurs from about March to September 1984. Bowhead whale and white whale migration,
and peaks in mid-summer. Age at sexual maturity in distribution, and abundance in the Bering, Chukchi
females is 4-7 years (based on two growth layers in and Beaufort Seas, 1975-1978. NOAA Tech. Rep.,
the teeth for estimating age) and 5-8 years for males. NUFS SSRF-778,39 p.
Ile calving intervals are generally every 3 years, but
about 25% calve every other year. Birth rate tapers Hazard, K. 1988. Beluga whale, Delphinapterus
off with age from a peak of about 0.333 at age 11-22 leucas, p. 195-235. In J. Lentfer. (ed.)., Selected
to 0.125 at age 29-38. The average life span isabout marine marnmals of Alaska. Species accounts with
30 years, but older animals up to 40 years have been research and management recommendations. Mar.
found in the wild. Gestation is presumed to last 14- Mammal Comm., 1825 Connecticut Ave NW, Room
15 months, although delayed implantation cannot be 512, Washington, D.C. 20009.

100 Marine Mammals

35. DALL'S PORPOISE

Dail's porpoise (Phocoenoides dalli) are widely mean take rate for observed salmon gill-net opera-
distributed across the entire subarctic North Pacific tions from 1981 to 1985 was OA7 porpoise per set
Ocean. Four color morphs of the same species have (15 Ian of net) inside the EEZ. The estimated
been identified. The P. dalli truei morph, common incidental catch outside the EEZ ranged from 479 to
along the Pacific coast of Japan, is black with a 1,716. These fisheries no longer operate in U.S.
white flank patch extending forward as far as the waters and are not monitored by U.S. observers
flippers, and a white throat patch. The P. dalli dalli outside the EEZ. -
morph is more cosmopolitan throughout the species' Incidental take by the Japanese squid fishery were
range; the white flank patch does not extend forward reported by the Fisheries Agency of Japan to be
beyond the dorsal fin, and there is no white throat 2,500 in 1982, 2,502 in 1983, and 2,515 in 1984.
patch. The third morph, which is uncommon, is a The observed take in 1989 was 141 Dail's porpoise,
solid black form occurring along the Sanriku coast of but this was based on monitoring only 4%-10% of
Japan and in the northwestern Pacific. Dail's the fishing effort by the fleet. The impact of com-
porpoise occur predominantly offshore but may be mercial fishing on Dail's porpoise is unknown.
inshore in some areas-, the southern extent of their
range is approximately lat. 28*N, which coincides For further information
with the 17*-18* C isotherm. The northern limit is
generally Cape Navarin, U.S.S.R., in the western Kasuya, t., and L. L. Jones. 1984. Behavior and
Bering Sea (lat. 62*N), although there are a few segregation of the Dail's porpoise in the northwest-
recorded sightings off northwest Alaska (i.e., ern North Pacific Ocean. Sci. Rep. Whales Res.
Chukchi and Beaufort Seas). Three populations or Inst., Tokyo 35: 107-128.
stocks are postulated for the western North Pacific
and adjacent areas: the truei morph off the Sanriku Kasuya, T., and S. Shiraga. 1985. Growth of Dail's
coast as far east as long. 180*; the dall! morph porpoise in the western North Pacific and suggested
between Japan and the Aleutian Islands; and the geographic growth differentiation. Sci. Rep. Whales
dalli morph in the Okhotsk Sea. Stock separation Res. Inst., Tokyo 36: 139-152.
has also been hypothesized for the eastern North
Pacific, but specific areas have not been proposed. Winans, G., and L. L. Jones. 1988. Electrophoretic
The reproductive cycles of animals in the Bering Sea variability in Dail's porpoise (Phocoenoides da1h) in
and western North Pacific are apparently out of the North Pacific Ocean and Bering Sea. J. Mam-
phase, further supporting the stock separation mal. 69: 14-21.
hypothesis.
Throughout most of the eastern North Pacific,
Dail's porpoise are present during all months of the
year, although there may be seasonal inshore-
offshore and north-south movements in Alaska, such
as out of Prince William Sound and areas in the Gulf
of Alaska and Bering Sea. Based on studies carried
out between 1978 and 1992, the minimum estimated
abundance of Dail's porpoise in the Bering Sea,
Aleutian Islands, and Gulf of Alaska is 417.000
(95% CI : 316,000-575,000) but does not include
Southeast Alaska.
The Japanese high-seas salmon mothership
fishery has been operating in the North Pacific since
1952. The estimated annual incidental take by the
Japanese in this fishery (1981-87) within the U.S.
F= ranged from 741 (1987) to 4,187 (1982). The

Marine Mammals 101

36.HARBOR PORPOISE

Harbor porpoise (Phocoena phocoena) in the Alaska. A single incidental capture from the Bering
eastern North Pacific Ocean range'from the Beaufort Sea was reported in 1982, and I I animals were
Sea, Alaska, to Point Conception, California, reported taken from Bering Sea during high-seas
although records of harbor porpoise from Los gillnet salmon fisheries between 1978 and 1987.
Angeles Harbor also exiSt. The smallest of the North The only documented study of incidental take of
Pacific porpoises, Phocoena is less than 6 ft long, harbor porpoise is from the Copper River Delta
dark grey on top and light-colored underneath and where 102 Phocoena were reported entangled in
has a proportionally large triangular dorsal fin. 1978 of which 44 were released alive.
Female harbor porpoise reach maturity at 3 years of
age and probably reproduce annually. Gestation For further information
lasts I I months. Maximum age is perhaps around
15 years. Harbor porpoise feed on schooling fish, Gaskin, D. E. 1983. The harbor porpoise: Regional
such as herring and capelin, but also euphausiids populations, status and information on direct and
and squid. indirect catches. Rep. Int. Whaling Comm. 34: 569-
The total number of harbor porpoise in Alaska is 86.
unknown. Some systematic surveys in Alaska for
other cetaceans have frequently included harbor Matkin, C. 0., and F. H. Fay. 1980. Marine
porpoise sightings. A seasonal peak of over 500 marnmal-fishery interactions on the Copper River
animals in Prince William Sound was estimated in and in Prince William Sound, Alaska, 1978. Mar.
the late 1970s. Densities of harbor porpoise in the Mammal Comm. Rep., MMC-78/70. (Available
eastern Bering Sea were estimated in the mid-1980s through NTIS, Springfield VA, as PB 80-159536.)
at 13 animals per 1,000 mnP. Three geographic
stock units have been proposed for Alaska: the Taylor, B. L., and P. K. Dawson. 1984. Seasonal
northern Bering Sea and adjacent Arctic waters; the changes in density and behavior of harbor porpoise
Aleutian Islands and southern Bering Sea; and the (Phocoena phocoena) affecting census methodology
Gulf of Alaska and Southeast Alaska. These in Glacier Bay National Park, Alaska Rep. Int.
divisions are not confirmed but are suggested based Whaling Comm. 34:479-483.
on oceanographic conditions and topography of the
am which might limit the movements of harbor Yurick, D. B. 1977. Populations, sub-populations,
porpoise. and zoogeography of the harbor porpoise, Phocoena
Insufficient information is available on abun- phocoena (L.). M. S. Thesis. University of Guelph.
dance and incidental mortality to make an assess- Guelph, Ontario, Canada. 148 p.
ment of the status of harbor porpoise populations in

102 Marine Mammals

37, NORTHERN SEA LION

A
, wur

:16_
al@ft e, A IOU

A _44w.

Aw-

Photo: Richard Merrick
The northern sea lion (Eunwtopiasjubatus), also Alaska to the Aleutian Islands, the sea lion popula-
known as the Steller sea lion, is endemic to the tion has declined from 67,617 counted in 1985 to
North Pacific Ocean. Its range is from the Kuril 20,679 in 1992 -- a decrease of 69% in just 7 years.
Islands, Russia, to California, north to lat. 630N and The greatest decline since the 1960s has been in the
south to lat. 330N. Breeding units occur throughout eastern Aleutian Islands (94% decline), the former
the species range, except in Washington. Sea lions center of abundance of the species. During the
exhibit strong site fidelity at about 50 rookeries, 1980s, all areas of the species' range declined except
range-wide, and disperse after reproduction but do in Southeast Alaska, British Columbia, and Oregon.
not migrate. Peak pupping is early June, and It is unclear why the decline has occurred or
lactation lasts 7 months to over I year. Sexual whether it is related to fishery activities or from
maturity occurs at age 4-6 in females, while gesta- some unknown natural environmental factor.
tion lasts 9 months after a 3-month delayed implan- Northern sea lions are the most frequent marine
tation. The mating system is polygamous. mammal taken in commercial fisheries. Incidental
Northern sea lions feed on Pacific salmon, squid, take in trawl fisheries in 1973-88 may have played
Pacific herring, groundfish (such as walleye pol- an important role in the decline in the 1970s, but not
lock), and other finfish species. Walleye pollock in the 1980s. Food availability is considered to be
greater thaii 25cm predominate in the sea lion's diet one plausible hypothesis. Other factors such as
seasonally in Alaska. Female summer feeding trips disease, predation, native subsistence and entangle-
can extend out to 20nmi: in winter the females may ment in nets and debris are not significant in the
forage out to several hundred miles. decline. Intentional shooting may have been impor-
Ile abundance of sea lions was first noticed to be tant at various times or areas.
declining in Alaska in 1976. Since the late 1960s the In 1990 the northern sea lion was listed as a
species has declined by about 70%. From the Gulf of threatened species under the Endangered Species

Marine Mammals 103
ru

Act. Since then, Federal action has been
taken to restrict certain fisheries activities Highest Counts of Northern Sea Lions
near sea lion breeding sites and potential in U.S. Waters
habitat important for feeding; some of this
habitat extends across much of the southern U.S. 1956-68 1975-77 1984-86 1989-92
Bering Sea and the Gulf of Alaska. A -----------------------------------------------
Alaska 150,572 129,347 89,295 34,844
recovery team and plan have been established Oregon' - 1,785 2,503 3,035
to assist the NUFS in managing the potential California 2 3,100 2,600 2,500 2,000
conflict between conserving northern sea
lions and the allocation of fish in domestic
fisheries. I Washington currently is 300-600.
2 Rounded; some extrapolations among years.
For further information

Braham, H., R. Everitt, and D. Rugh. 1980.
Northern sea lion population decline in the
eastern Aleutian Islands. J. Vrddl. Manage.
44: 25-33.

Loughlin, T., and R. Merrick. 1989. Com-
parison of commercial harvest of walleye
pollock and northern sea lion abundance in
the Bering Sea and Gulf of Alaska. In
Proceedings of the International Symposium
on the Biology and Management of Walleye
Pollock. p. 679-700. Alaska Sea Grant Rep.
No. 89-1.

Loughlin, T.R., A.S. Perlov, and V.A.
Vladimirov. 1992. Range-wide survey and
estimation of total abundance of Steller sea
lions in 1989. Mar. Mammmal Sci. 8:220-
239.

Merrick, R., T. Loughlin, and D. Calkins.
1987. Decline in abundance of the northern
sea lion in Alaska, 1956-86. Fish. Bull.,
U.S. 85: 351-365.

104 Marine Mammals

38. NORTHERN FUR SEAL

The northern fur seal (Callorhinus ursinus) is a may not return to their islands of birth each year.
monotypic species ranging across the subarctic Fur seals tend to concentrate along the continental
waters of the North Pacific Ocean from the Sea of shelf and slope where nutrient-rich waters support a
Japan, Okhotsk Sea, and Bering Sea, and southward variety of prey species. Some fur seals have been
along the coast of the temperate continental United seen far at sea and are occasionally taken in high-
States. Breeding populations are found on Robben seas gill-net fisheries. Ile southern extent of the
Island (Okhotsk Sea); several Kuril Islands (south of migratory range in the eastern North Pacific Ocean
Kamchatka); on the Commander, Pribilof (St. Paul is to about lat. 32oN (California-Mexico boundary)
and St. George Islands), and Bogoslof Islands (all in and in the western North Pacific Ocean to about
the Bering Sea); and on San Miguel Island (southern lat. 36*N (off Honshu Island, Japan). The northern
California). extent of the range is in the Bering Sea.
Most mature fur seals are on or near their Older male fur seals (age 10- 15 years) from the
breeding islands from June to November and spend Pribilof Islands winter farther north in the North
the remaining months at sea. Immature seals may or Pacific Ocean thaii younger males and females.

Marine Mammals 105

Females and young males appear Northern Fur Seal
during their southbound migration Eastern Bering Sea
along the continental shelf from
about IaL 570N to 46ON in late Pup Counts (in thousands)
November and off California (40ON 350 L
to 38*N) in late December. In 300-
January-April, major concentrations
occur between Calffornia and British 250- T
Columbia. The spring (northbound) 200-
migration begins as early as March;
some seals follow the continental 150 -
01
shelf and then go westward through 100-
the Gulf of Alaska and into the
50
Bering Sea through the eastern 0 01 Jill 1 1101 H
Aleut= Island passes. Older (10- 70 72 74 76 78 82 8'4 8'6 88 @O
15 yew olds) males usually arrive
first on the islands in May and are M St. George Island =St. Paul island
followed by the older females by late
June. Younger males and females
continue to arrive throughout summer. For further information
The estimated total number of northern fur seals
in the North Pacific Ocean in 1983 was 1.2 million. Fowler, C. W. 1988. A review of seal and sea lion
The pre-exploitation level of fur seals is unknown; entanglement in marine fishing debris. In D.L.
the best estimate is that the Pribilof Islands popula- Alverson and J. A- June (eds.), Proceedings of
tion originally numbered between 2 and 3 million Pacific Rim Fishermen's Conference on Marine
animals prior to the 19th century. By the early Debris, Kailua-Kona, Hawaii, 13-16 October 1987.
1950s, the Pribilof herd was believed to be approach- Available Nabiral Resources Consultants, 4055- 21st
ing this level, and was probably close to the can-ling Ave W., Seattle, WA 98199.
capacity of the ecosystem at that time. The popula-
tion size on the Pribilof and Bogoslof Islands in Fowler, C. W. 1990. Density dependence in
1988 was 982,000; this level is significantly less northern fur seals (Callorkinus ursinus). Mar.
(about two-thirds) than observed in the 1950s when Mammal Sci. 6(3): 171-195.
the population had reached its highest levels this
century. Data collected in the 1950s, when com- Loughlin, T. R., and I;L V. Miller. 1989. Growth of
pared to those from the 1980s through 1990, show the northern fur seal colony on Bogoslof Island,
that 1) pup production on St. Paul Island is down by Alaska Arctic 42(4): 368-372.
about 60%; 2) territorial males with females on St.
Paul Island are down about 63%; and 3) the rookery Scheffer, V. B., C. H. Fiscus, and E. 1. Todd. 1994.
area occupied on St. Paul Island in 1985 was less History of scientific study and management of the
than one-third the area used in 1948. The current Alaskan fur seal (Callorhinus ursius), 1786-1964.
rate of growth of the herd is not significantly NOAA Tech. Rep. NMFS SSRF-780,70 p.
different from zero, although pup production on St.
George Island continues to decline at 6% per year. York, A. E., and P. Kozloff. 1987. On the estima-
Fur seals are taken incidentally in the high-seas tion of numbers of northern fur seal, Callorhinus
foreign gill-net fisheries for squid and salmon. In ursinus, pups born on St. Paul Island, 1980-1986.
1989, 208 fur seals were taken (52 dead, 128 alive, Fish. Bull., U.S. 85: 367-375.
28 lost) in 1,402 observed net retrievals (about 4-
10% of the fishing operations). They are rarely
taken in domestic trawl and longline fisheries. Only
1-3 fur seal were taken by trawl nets in 1990.

106 Marine Mammals

39. HARBOR SEAL

-V

. . . . . . . . . . . .

-:07

Harbor seals (Phoca vitulina richardsi) range Harbor seals am commonly caught incidental to
from southeast Alaska to the central Bering Sea (to subsistence and commercial net fisheries; however,
about lat. 59*N). They primarily occur in coastal the nature and magnitude of the incidental take is
waters where they haul-out on sand bars and rocky generally unknown. Incidental take could have a
shores to give birth, molt, and rest. Mating gener- significant impact considering the extent of net
ally takes place in early summer. Delayed blastocyst fishing along the coast of Alaska. The number of
development of 1.5-3 months is normal, which seat reported taken in foreign commercial trawl
usually takes place during the molt (late summer and fisheries in the 1970s and the early 1980s was less
autumn). Lactation lasts from 3 to 6 weeks. Age at than 10. Only two harbor seals were reported taken
first pregnancy is 3-6 years, but this varies through- in domestic trawl fisheries in Alaska in 1990.
out Ainska
The total abundance of harbor Harbor Seal
seals in Alaska is unknown. Studies Tugidak Island, Alaska
conducted in the 1970s and 1980s on
Tugidak Island (southwest of Kodiak 8Adult & Juvenile Counts (Numbers)
Island) indicate that the population
there declined 86% over a 16-year 7 -
period from 6@919 in 1976 to 571 in 6
1992. Similar trends may be
occurring at other area , such as 5
along the north side of the Alaska 4
Peninsula, but studies needed to
determine the extent of the decline 3
only began in 199 1. Preliminary 2
results of those studies indicate a
continuing decline in harbor porpoise 1
abundance in the Gulf of Alaska and 0
stable numbers in Bristol Bay. 1976 1978 1980 1982 1984 1986 1988 1990 1992
Year

Marine Mammals 107

Observations of nearshore salmon fisheries in the
Cooper River Delta, Prince William Sound, and
Unimak Pass area only began in 1989. Ile exten-
sive net fisheries in other parts of the state have not
been monitored.

For further information

Everitt, R., and H. W. Braham. 1980. Aerial survey
of Pacific harbor seals in the southeastern Bering
sea. Northwest Sci. 54: 281-288.

Hoover, A. A. 1988. Harbor seal, Phoca vitulina, P
107-157. In J.W. Lentfer (editor), Selected marine
mammals of Alaska Species accounts with research
and management recommendations. Mar. Mamm.
Comm., 1825 Connecticut Ave NW., Room 512,
Washington, D.C 20009.

Perez, M. A., and T. R. Loughlin. 1990. Incidental
catch of marine mammals by foreign and joint
venture trawl vessels in the US. EEZ of the North
Pacific, 1973-88. U.S. Dep. Commer., NOAA Tech.
Rep., NMFS F/NWC-186,81p.

Pitcher, K. W. 1990. Major decline in number of
harbor seals, Phoca vitulina richardsi, on Tugidak
Island, Gulf of Alaska. Mar. Mammal Sci. 62: 12 1 -
134.

108 Marine Mammals

40. SPOTTED SEAL

V-4

Az -

VC V4@
Photo: Dav1d Rugh

Spotted or larga seals (Phoca largha) are distrib- pollock concentrations.
uted along the continental shelf of the Beaufort, Molting occurs during late spring. Loose groups
Chukchi, Bering, and Okhotsk Seas south to the of up to 200 animals can be found associated with
northern Yellow Sea and western Sea of Japan. ice remnants, although some seals also molt on land
Eight distinct breeding areas have been identified on the eastern Bering Sea coast. This allows these
with three in the Bering Sea: 1) Bristol Bay to the seals to take advantage of spring migrations of
Pribilof Islands; 2) Navarin Basin to the Gulf of Pacific herring. Animals move northward and
Anadyr (Russia); and 3) eastern Kamchatka Penin- inshore to the Alaskan and Siberian coasts as ice
sula (Russia), from Karaginskii Bay to Olyutorski degrades and recedes. Lagoons, estuaries, mainland
Gulf and north into the northern Bering Sea. beaches, offshore islands, and pack-ice near land are
Spotted seals are usually associated with the used as haulout sites.
southern extent of the pack ice in winter and spring, The current abundance of spotted seals in Alaska
but haulout on land in the northern part of the range is unknown. In 1973 the Bering Sea population of
in summer and fall. Pupping occurs in the Bering spotted seal was estimated to have been 200-250,000
Sea from late March through mid-May. Mating animals. This was based on opportunistic sightings
occurs at the time pups are weaned, about 4 to and relative abundance with other species. Adult
6 weeks postpartum. During this period, adults are recruitment is estimated to be 9%-11 %, but the
seen on ice floes as female-pup, male-female, or growth rate of the population is unknown.
male-female-pup triads. Sub-adults and non- Walleye pollock, capelin, Arctic cod and herring
breeding animals are generally found in larger are major prey items for spotted seals in the Bering
groups. In the southeastern Bering Sea, herds of Sea. The importance of competition between these
spotted seals are found in close proximity to walleye seals and fisheries cannot be assessed at this point,

Marine Mammals 109

however, because data on the population dynamics Lowry, L. F., and K. J. Frost. 1981. Feeding and
and behavior of spotted seals are lacking. Based on trophic relationships of phocid seals and walruses in
the spotted seal's diet, utilization of the Bering Sea the eastern Bering Sea, p.813-824. In D.W. Hood
for feeding, foraging strategy, and population and J. A. Calder (editors), The eastern Bering Sea
distribution, spotted seals are likely to interact shelf. Oceanography and resources., Volume 2.
directly with both the commercial groundfish and Juneau, All*-q, U.S. Dep. Commer., NOAA Off.
herring fisheries. U.S. fishery observers on foreign Mar. Poll. Assess.,'U.S. Gov. Print. Off., Washing-
independent fishing vessels and joint venture mother ton, D.C.
ships recorded the number of marine mammals
caught in ground fisheries from 1978 to the present. Quackenbush, L. T. 1988. Spotted seal, Phoca
Between 1978 and 1986 at least 2 and perhaps as largha, P. 107-124. In J.W. Lentfer. (editor),
many as 22 spotted seals were observed caught, and Selected marine mammals of Alaska. Species
all died. Uncertainties in this estimate are due to accounts with research and management recommen-
potential misidentification of seals. Twenty seals dations. Nfar. Mamm. Comm., 1825 Connecticut
were caught in areas inhabited by both spotted seals Ave NW., Room 512, Washington, D.C 20009.
and harbor seals but were all identified as harbor
seals.
During the 1960s and 1970s, Russian commercial
sealing and Alaskan Eskimo subsistence harvests
averaged about 4-8,000 spotted seals per year in the
Bering Sea, or about 3% of the juvenile and adult
population. However, takes for both groups have
apparently declined in recent years. Data are not
available to assess the impact of intentional taking
by domestic fisheries.

For further information

Braharn, H. W., J. J. Bums, G. A. Fedoseev and B.
D. Krogman. 1984. Habitat partitioning by ice-
associated seals and walruses in the Bering Sea,
April 1976, p. 25-47. In F. H. Fay and G. A.

Fedoseev (editors), Soviet-American cooperative
research on marine mammals, Volume 1. Pinnipeds.
U.S. Dep. Commer., NOAA Tech. Rep. 12.

Bums, J. J. 1970. Remarks on the distribution and
natural history of pagophilic pinnipeds in the Bering
and Chukchi Sea. J. Mammal. 51: 445-454.

110 Marine Mammals

RECENT TECHNICAL MEMORANDUMS

Copies of this and other NOAA Technical Memorandums are available from the
National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22167.
Paper copies vary in price. Microfiche copies cost $3.50.

AFSC-

26 LOW, L-L. (coordinator). 1993. Status of living marine resources off the Pacific coast of the United
States for 1993, 90 p. NTIS number pending.

25 KINOSHITA, R. K., A. GREIG, J. D. HASTIE, and J. M. TERRY. 1993. Economic status of the
groundfish fisheries off Alaska, 1992, 102 p. NTIS number pending.

24 SINCLAIR, E. H. (editor) 1993. Fur seal investigations, 1991, 142 p. NTIS No. P1394-118171.

23 PARKS, N. B., F. R. SHAW, and R. L HENRY. 1993. Results of a 1988 trawl survey of groundfish
resources of the upper continental slope off Oregon, 164 p. NTIS No. PB94-118163.

22 YANG, M-S. 1993. Food habits of the commercially important groundfishes in the Gulf of Alaska
in 1990, 150 p. NTIS No. PB94-112463.

21 KINOSHITA, R. K., and J. M. TERRY. 1993. Oregon, Washington, and Alaska exports of edible
fishery products, 1992, 52 p. NTIS No. P1393-226652.

20 REEVES, J. E. 1993. Use of lower minimum size limits to reduce discards in the Bristol Bay red
king crab (Paralithodes camtschaticus) fishery, 16 p. NTIS No. PB93-228187.

19 SYRJALA, S. E. 1993. Species-specific stratification and the estimate of groundfish biomass in
the Eastern Bering Sea, 20 p. NTIS number pending.

18 PELLA, J., M. HOFFMAN, S. HOFFMAN, M. MASUDA, S. NELSON, and L. TALLEY. 1993. Adult
sockeye and pink salmon tagging experiments for separating stocks in northern British Columbia
and southern Southeast Alaska, 1982-1985, 134 p. NTIS No. P1393-226660.

17 SEASE, J. L., J. P. LEWIS, D. C. MCALLISTER, R. L. MERRICK, and S. M. MELLO. 1993. Aerial
and ship-based surveys of Steller sea lions (Eumetopias jubatus in Southeast Alaska, the Gulf of
Alaska, and Aleutian Islands during June and July 1992, 57 p. NTIS No. PB93-226025.

16 FISCUS, C. F. 1993. Catalogue of cephalopods at the National Marine Mammal Laboratory, 183
p. NTIS No. P1393-226678.

15 KINOSHITA, R. K., A. GREIG, L. E. QUEIROLO, and J. M. TERRY. 1993. Economic status of
the groundfish fisheries off Alaska, 1991, 94 p. NTIS No. P1393-197861.

14 PEREZ, M. A., and W. B. MCALISTER. 1993. Estimates of food consumption by marine mammals
in the Eastern Bering Sea, 36 p. NTIS No. P1393-191195.

13 BERGER, J. D. 1993. Comparisons between observed and reported catches of retained and
discarded groundfish in the Bering Sea and the Gulf of Alaska, 89 p. NTIS No. PB93-18471 1.

12 HARRISON, R.C. 1993. Data report: 1991 bottom trawl survey of the Aleutian Islands area,144 p.
NTIS No. P1393-186237.

3 6668 00003 9612