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

                                           INVESTIGATION OF A WEIR DESIGN  ALTERNATIVE

                                                     FOR COASTAL FISHERIES BENEFITS

                                                              BARTON D. ROGERS, M.S.
                                                              WILLIAM H. HERKE, PH.D.
                                                                E. ERIC KNUDSEN, M.S,

                                                                         FUNDED      BY
                                                  UNITED STATES ARMY CORPS                    OF   ENGINEERS
                                              LOUISIANA DEPARTMENT OF NATURAL RESOURCES
                                          LOUISIANA STATE UNIVERSITY AGRICULTURAL CENTER
                                   LOUISIANA STATE UNIVERSITY COASTAL                            FISHERIES INSTITUTE
                                                UNITED STATES FISH AND WILDLIFE SERVICE

                                          LOUISIANA COOPERATIVE FISH AND WILDLIFE RESEARCH UNIT
                                          SCHOOL OF FORESTRY, WILDLIFE, AND FISHERIES
              SH                       LOUISIANA STATE UNIVERSITY AGRICULTURAL CENTER
              365                                  BATON ROUGE, LOUISIANA 70803-6202
              .L8
              R64                                                    FEBRUARY 1987
              1987

                 This public document was published at a total cost of $312.62.        150
                 copies of this document were published in the first printing at a cost
                 of $181.37.   The total of all printings of this document, including
                 reprints is $312.62.   This document was published by the Department
                 of Natural Resources, P.O. Box 44487, Baton Rouge, Louisiana 70804,
                 to inform the public about Coastal Zone Management under the authority
                 of Public Law 92-583 and La. R.S. 49:213.     This material was printed
                 in accordance with the standards for printing by state agencies
                 established pursuant to La. R.S. 43:31.

                                                 'ACKNOWLEDGMENTS

                           This study was a success due to the hard work, sacrifice, and
                      perseverance of the field crew: Ms. Cora Cash and Messrs. Ralph Allemand
                      (Field Supervisor), Marc Fugler, and William Sanderson. Data had to be
                      collected every day and 2/7ths of the data were collected on weekends.

                           This study was funded by five institutions: the U. S. Army Corps of
                      Engineers (Agreement No. 14-16-0009-86-1817), the Louisiana Department
                      of Natural Resources (Contract No. 21910-86-10), the Louisiana State
                      University Coastal Fisheries Institute, the Louisiana State University
                      Agri-cultural Center, and the United States Fish and Wildlife Service.

                           Dr. James Geaghan provided statistical consultation for the data
                      analysis. Ms. Dawn Brady provided great assistance in the
                      administration of this project. The study area and logistical
                      assistance were provided by the Sabine National Wildlife Refuge of the
                      U. S. Fish and Wildlife Service. The field facilities were constructed
                      under a previous project that was funded by the U. S. Soil Conservation
                      Service. They also were instrumental in developing the study concept by
                      providing much needed technical input. The Louisiana-Department of
                      Wildlife and Fisheries assisted in the computerized reading of the water
                      level gauge tapes. The Cotton-Miami Corporation graciously allowed us
                      to use their launch ramp and to cross their land in order to access our
                      study site. This was of great Assistance, because otherwise we would
                      have had to go through Calcasieu Lake on a daily basis. Figures 1,
                      and 3 were prepared by Ms. Michelle LaGory.

                           Appreciation is extended to the following reviewers: Mr. Thomas
                      Schultz, Mr. Richard Hartman, Mr. Don Moore, Dr. Gil Bane, Mr. Darryl
                      Clark, Mr. Fred Dunham, and the Environmental Branch of the New Orleans
                      District, U. S. Army Corps of En gineers.

                                                         U.S. DEPAIRTMP,11 0@ ('0P,!VER('F NIOAP.

                                                         2 2                     N 11
                                                         r                    0 b    3

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                                                 TABLE OF CONTENTS

                                                                                               PAGE

                          ACKNOWLEDGMENTS  ...................................................   i

                          LIST OF TABLES  ....................................................  iii

                          LIST OF FIGURES  ...................................................  iv

                          ABSTRACT  ..........................................................   v

                          INTRODUCTION  ......................................................   1

                          METHODS AND PROCEDURE .............................................    4

                            Trap  ............................................................   4
                            Trawling  ........................................................  11
                            Data Analysis  .................................................... 11
                          RESULTS AND DISCUSSION  ............................................  13

                            Brown Shrimp  ....................................................  13
                               Brown Shrimp Conclusions  .....................................  21
                            Species Composition .............................................   22
                               Species Composition Conclusions  ..............................  26

                            Environmental  ...................................................  28

                               Salinity  .....................................................  28

                               Water Level  ..................................................  31

                               Water Temperature  ............................................  34

                               Environmental Conclusions  ....................................  34

                          GENERAL DISCUSSION  ................................................  36

                          CONCLUSIONS  .......................................................  42

                          LITERATURE CITED  ..................................................  44

                          APPENDIX  ..........................................................  47

                               Tables  .......................................................  47

                               Figures  ......................................................  53

                                                     LIST OF TABLES

                        TABLES                                                              PAGE

                          1.  Trap catch, biomass, and percent change for both
                              experimental ponds  ..........................................  14

                          2.  Mean weight in grams, and percent change, of an
                              individual organism taken by the traps  ......................  17

                          3.  Number and biomass taken by both trawls in the
                              three ponds  .................................................  20

                          4.  Mean weight (grams) of organisms derived from the
                              combined catch from both trawls for the duration
                              of the study  ................................................  27

                          5.  Summary statistics for the daily physical measurements
                              for the experimental ponds (at the levee station) and
                              Grand Bayou; and physical data collected while trawling
                              in the three ponds  ..........................................  33

                          6.  Catch of abundant, or economically-important, organisms
                              taken by Herke et al. (1987b)(15 February 1983 through
                              30 July 1983) and this study (15 February 1986 through
                              30 July 1986)  ...............................................  38

                                                           LIST OF FIGURES

                             FIGURE                                                                     PAGE

                              1.   Grand Bayou study area showing the paired ponds and
                                   the trawling station in the control pond      .....................    5

                              2.   Diagram of the paired ponds showing the trawling stations
                                   (WE, WB, EE, and EB), the Grand Bayou salinity stations
                                   (A and B), and the levee salinity stations in each pond        ......  6

                              3.   Diagram of the experimental-ponds trapping system showing
                                   the location of the standard and slotted weirs and the
                                   environmental stations    .......................................      7

                              4.   Sketch of the slotted weir as viewed from the end of the
                                   chute  ........................................................        9

                              5.   Number, biomass, and mean weight of brown shrimp taken by
                                   the traps in each pond    .......................................     16

                              6.   Number, biomass, and mean weight of brown shrimp taken by
                                   the trawls in each pond    ......................................     19

                              7.   Number of species, total number of individuals, and
                                   biomass of all emigrating species taken by the trap
                                   in each experimental pond   ....................................      24

                              8.   Number of species, total number of individuals, and
                                   biomass of all emigrating species taken by the trawls
                                   in each experimental pond   ....................................      25

                              9.   Daily salinity readings taken at the environmental and
                                   levee stations, and the mean salinity taken at the
                                   trawling stations, for both experimental ponds       ...............  29

                              10.  Salinity in both ponds (as measured at the levee stations)
                                   and in Grand Bayou (average of stations A and B)       .............  30

                              11.  Water level for the experimental ponds and Grand Bayou        ....... 32

                              12.  Brown shrimp catch for 1983 and 1984 (Herke et al. 1987b)
                                   and 1986 (this study) at the experimental ponds       ..............  39

                                                                   iv

                                                        ABSTRACT

                             Standard fixed-crest weirs have been demonstrated to reduce fish
                        and crustacean emigrations from the marsh nursery area back toward the
                        Gulf of Mexico. These weirs are continuing to be constructed for
                        wildlife habitat enhancement. The effect of weirs on emergent
                        vegetation is unclear although some research has suggested that emergent
                        marsh vegetation in water-logged soils may experience reduced growth.

                             The objective of this study was to determine whether modification
                        of a standard fixed-crest weir would result in greater export of fishery
                        organisms from the area controlled by the weir. Total catch of
                        emigrating organisms was taken from two nearly identical marsh ponds by
                        traps with a mesh opening of 0.203 inch. Both ponds had a standard
                        fixed-crest weir at the only entrance/exit, with one weir having a
                        vertical slot from top to bottom. Data were collected from 15 February
                        through 30 July 1986, which encompassed the majority of the brown shrimp
                        (Penaeus aztecus) marsh nursery cycle. Salinity, water temperature, and
                        water levels were measured in both ponds and in the nearby waters.
                        Trawling was conducted in these experimental ponds and in a nearby
                        control pond, which had no water-control structure.

                             Over 241% more brown shrimp (84% in biomass) emigrated from the
                        pond with the slotted weir than from the pond with the standard weir.
                        Both the standard and slotted weir were suspected of delaying immi-
                        gration and emigration for brown shrimp. The slotted weir apparently
                        yields median results between the control pond (early and abundant
                        immigration, early emigration, low mean size, and high rate of cycling)
                        and the standard weir (later and less abundant immigration, delayed
                        emigration, increasing greater mean size, and low rate of cycling).

                             For all species combined, over 60% more organisms (62% in biomass)
                        emigrated from the slotted-weir pond for the study period. For the time
                        period studied, the salinities and water levels were generally similar.
                        Water levels in the slotted-weir pond had slightly greater range and
                        standard deviation, however the water level in the slotted weir pond did
                        not drop nearly as low as the water levels outside the experimental
                        ponds.

                             Compared to a standard fixed-crest weir, a slotted weir would
                        provide enhanced fishery access and utilization. The slotted
                        and standard weirs should be evaluated for their effect on emergent
                        vegetation, water levels, salinities, and wildlife and fishery organisms
                        other than brown shrimp.

                                                            v

                                                      INTRODUCTION

                             Standard fixed-crest weirs have been implicated in affecting the
                        movements and abundance of many estuarine organisms (Herke 1968, 1971,
                        1979; Wengert 1972; Herke et al. 1984a, 1985, 1987a,b). Most of the
                        economically-important species that spawn nearshore and migrate into the
                        marsh nursery areas have been either less abundant in.these
                        semi-impounded areas (those affected by we4rs) (Wengert 1972, Herke et
                        al. 1987a) or the fisheries export from the nursery area was reduced
                        (Herke et al. 1987b). Perry (1981) concluded that weirs did not prohib-
                        it brown shrimp (Penaeus aztecus) from entering the marsh because he
                        found shrimp behind a weir; however, he had no control (non-weired).area
                        for comparison. Thus, he was unable to determine whether brown shrimp
                        movement and abundance was reduced by the weir. Several other studies
                        documented shrimp behind weirs, but these have only been a measure of
                        standing crop and did not considered the turnover rate (cycling in and
                        out). The productivity of an area can not be based on standing crop
                        alone, but must consider the cycling of organisms. Two areas may have
                        equal standing crops, but one could have many times the productivity, if

                        the turnover rate is greater.
                             The actual behavioral mechanisms by which water-control structures
                        affect the movement of organisms are not kncwn. One likely mechanism is
                        the reduction in water exchange. Herke et al. (1984b) and Schultz
                        (1985) demonstrated that most of the organisms move with the current.
                        Bradshaw (1985) found significantly lower densities of postlarval and
                        juvenile brown shrimp in a semi-impounded area as compared to an adja-
                        cent non-weired area. Thus, the reduction in water exchange may reduce
                        the number of the young larval and juvenile immigrants. Another possi-
                        ble mechanism is the creation of an ethological barrier by weirs (Herke
                        1979). That is, the organisms could physically cross the weir but
                        behavioral traits prevented their crossing. Another likely mechanism is
                        the blocking by weirs of a specific portion of the water column at which
                        certain organisms would prefer to migrate; e.g., Herke et al. (1984a)
                        suggested that weirs may impede the movement of juvenile spotted sea-
                        trout (Cynoscion nebulosus) entering the marsh because they migrate at
                        the middle and lower portions of the water column. King (1971), Herke
                        et al. (1984b, 1987b), Rogers and Herke (1985a,b), and Schultz (1985)

                                                                                                2

                        present data on the vertical migration levels of many organisms.
                             Weirs have been used for many purposes, in Louisiana they have been
                        traditionally used to enhance the habitat for waterfowl and furbearers
                        (Chabreck and Hoffpauir 1965; Chabreck 1968). Weirs maintain a minimum
                        water level and sometimes reduce turbidity, thereby stimulating the
                        growth of widgeongrass, Ruppia maritima, and other submerged aquatic
                        vegetation, important food plants for waterfowl (Wicker et al. 1983).
                        The effects of weirs on other types of vegetation have not been well
                        studied. Weirs are installed to reduce marsh erosion, although we know
                        of no documented evidence that they are effective for this purpose in

                        brackish or saline marshes.
                             Mendelssohn and Seneca (1980) and Mendelssohn et al. (1980) have
                        demonstrated that saltmarsh cordgrass, Spartina alterniflora, has lower
                        levels of standing crop and growth when the drainage is impaired or the
                        plants are in waterlogged soils. These authors attribute decreased
                        growth to increased anaerobic metabolism and subsequent increases in
                        waste products of anaerobic metabolism, e.g. sulfides. Perhaps the
                        longer inundation period caused by the weirs may be detrimental to
                        saltmeadow cordgrass, Spartina patens, as well. At this point, not
                        nearly enough is known about the short or long term effects of weirs on
                        the marsh and the emergent vegetation.
                             Perhaps better structures can be designed that will perform basi-
                        cally the same marsh management functions as those of fixed-crest weirs,
                        while allowing greater fishery organism usage and movement. Such
                        structures may greatly improve fishery resources, while maintaining or
                        enhancing benefits to other wildlife (especially when considering the
                        questionable effects of weirs on emergent vegetation).
                             The objectives of this study were to; 1) compare the catches of
                        fishery organisms emigrating from two marsh ponds, one having a standard
                        fixed-crest weir and the other having the same weir structure but mod-
                        ified to include a 4-inch vertical slot from top to the bottom of the
                        channel, and 2) monitor water level, salinity, and water temperature in
                        each pond. Although several structures were discussed as possible test
                        designs, the vertically-slotted, fixed-crest weir was chosen due to the
                        ease of design and construction., lower cost, and the allowance of move-
                        ment of organisms throughout the entire water column. When applied in

                        marsh management, this slotted design would improve fisheries access
                        with minimal active structural management and would allow easy closing
                        of the slot, if necessary.

                                                                                              4

                                                METHODS AND PROCEDURES

                                                          Trap
                           This study utilized two marsh ponds that were located in the East
                       Cove portion of the Sabine National Wildlife Refuge in the Grand Bayou
                       watershed, Cameron Parish, Louisiana (Fig. 1). These ponds were also
                       used by Herke et al. (1987b). The ponds were constructed in October
                       1982 by surrounding a portion of a single natural marsh pond with a ring
                       levee and installing a cross levee, such that the natural pond was
                       divided into two 87-acre experimental ponds (Fig. 2). Each pond
                       enclosed about 65 acres of water and 22 acres of predominantly Spartina
                       patens marsh. These two ponds will be collectively referred to as the
                       experimental ponds. The control pond (Fig. 2) had no water-control
                       structure and was used only for trawl sampling (to be presented later).
                           A single wooden chute, constructed of plywood and pilings, installed
                       in each pond levee, was the only entrance/exit channel for tidal ex-
                       change and aquatic organisms (Fig. 3). These chutes were 6 feet wide, 8
                       feet deep and 40 feet long. The bottom of each chute was about 4 feet
                       below average water level. Identical trap systems were installed in
                       each chute (Fig. 3). Each trap was 6 feet tall, 6 feet long, and 2 feet
                       wide, and was constructed of welded aluminum alloy covered with monel,
                       market-grade, wire cloth, having 0.047-inch diameter wire and 0.203-inch
                       openings. The end of the trap facing the pond had a V-shaped mouth with
                       a 2-inch vertical slit to funnel emigrating organisms into the trap. A
                       similar mouth with a 3/4-inch vertical slit was placed in the middle of
                       the trap to allow smaller organisms to retreat to the rear of the trap
                       (Fig. 3). This was done to segregate the larger blue crabs (Callinectes
                        apidus) from the smaller organisms, which hampered the crabs from
                       mutilating or consuming the smaller organisms. Deflecting screens, made
                       of the same mesh as that of the traps, were installed to guide immigrat-
                       ing organisms toward a 3-inch (7.62 cm) slot at the pondward edge of the
                       chute and deflecting screens (Fig. 3). This 3-inch slot had a deflector
                       placed on the pon dward side to guide outgoing organisms past this slot.
                       The deflecting screens also guided emigrating organisms into the trap.
                       Thus, immigrants were easily guided into the ponds but all emigrants too
                       large to pass through the mesh were trapped.
                            A complete history of the various water-control structures used at

                                                   CMD

                                                      we i

                             !@j
                             VI

                                                                                                      CY

                                                              ng

                                                                                                            N@

                                  EXPERIMENTAL       1,0P
                                      PONDS

                                                                CONTROL
                                                                  POND
                                     L                                                     0          2    3

                                                                                                  km
                                                                                       V,@a         -11

                                     Figure 1. Grand Bayou  study area showing the paireId ponds and the trawl
                                                stations in the control pond.

                                            N

                                                                                   A

                                                                                                7?
                                                            Area Enlarged
                                                                            WE
                                                               in Figure 3
                                                STANDARD-WEIR POND                                          B

                                                WB
                                                                                EE

                                                                LEVEE
                                                               STATIONS

                                                       EB
                                                                   SLOTTED-WEIR POND
                                                                                                0

                                                                                                        0

                                                                                                            ry
                             Figure 2. Diagram of the paired ponds showing the trawling station s (WE, WB, EE,
                                        and EB), the Grand Bayou salinity stations@(A and B), and the levee
                                       salinity stations in each pond.

                                                                                    STANDARD
                                           To
                                         POND                                          WEIR
                                                                                                                                11-0

                                 ENVIRONMENTAL
                                    STATION                                             CHUTE

                                                                                                                              SLOTTED WEIR

                                                                                                           LK

                                              RAMP

                                                  r2-                      TRAP

                                                                                                       DEFLECTING
                                                                                                           SCREENS                                        '0
                                                                                                                                                           0
                                    0
                                                                        76-cm wide
                                                                         VERTICAL
                                                                             SLIT

                                                                                                                                       RAMP

                                                                                                                                              ENVIRONMENTAL
                                                                                                                                                   STATION

                                    Figure 3. Diagram of the experimental-ponds trapping system showing                             the  location of
                                                   the standard and slotted weirs and the environmental stations.

                                                                                                       8

                        these experimental ponds by Herke et al. (1987b) and during this study

                        is as follows:

                                                                             Pond

                                       Dates                        East               West

                                12 Feb 1983  - 13 Feb 1984          weir             no weir
                                13 Feb 1984  - 20 Apr 1985         no weir              weir
                                20 Apr 1985  - 24 Aug 1985         no weir           no weir
                                24 Aug 1985  - 22 Nov 1985         no weir              weir
                                22 Nov 1985  - 20 Dec 1985         no weir           no weir
                                20 Dec 1985  - present           slotted-weir           weir

                             On 22 November 1985 the weir on the west pond was removed, to allow
                        both ponds to be open (no structure), with the idea to let the ponds
                        equilibrate in terms of salinity, water level, and fishery organisms.
                        On 20 December 1985, a standard, fixed-crest weir (referred to as the
                        standard weir) was installed on the Grand Bayou side of the trap in the
                        west pond chute (Figs. 2 and 3). The crest of this weir was set 6
                        inches below average marsh soil level and had a length of 65 inches. On

                        the same date, a standard fixed-crest weir with a 4-inch vertical slot
                        (referred to as the slotted weir) was placed in the chute for the east
                        pond. This vertical slot stopped 3 inches from the bottom, because a 3-
                        X 6-inch timber was used for support across the bottom (Fig. 4). The
                        3.5- X 3.5-inch vertical timbers and the interior stoplog guides reduced
                        the crest of the slotted   weir to 61 inches (Fig. 4). Thus the slot
                        width comprised 6.5% of the weir crest length, i.e., 1 inch of slot per
                        15.2 inches of weir crest length. The weir crest length was longer than
                        normally used in practice (e.g. 1 foot of weir crest per 70 acres of
                        semi-impounded marsh) because 6-foot wide chutes were necessary for
                        installation of the traps and deflecting screens.
                              Fish, shrimp, and crabs migrating into the ponds, after negotiating
                        either weir, could either pass through the mesh of the deflecting
                        screens and trap, or through the 3-inch wide vertical slot at the
                        pondward end of the deflecting screens (Fig. 3). Incoming organisms too
                        large for this opening were excluded; however, most were small enough to
                        gain access. All organisms too large to pass through the mesh were
                        captured when emigrating from each pond. The traps fished continuously

                                                                                            9

                                                                             naslil
                                                                             LEVEL
                                       STOPLOG->t
                               J.
                                     <--GUIDES

                                                                        14CHUTE
                                                                           FLOOR

                         Figure 4. Sketch of the slotted weir as viewed from the end of
                              the chute. The 61-inch weir crest was set at 6 inches
                              below average marsh soil level. The 4-inch slot went
                              from the weir crest to within 3 inches from the floor of
                              the chute. The bottom stoplog was one continuous timber
                              to provide support for the interior stoplog guides.

                                                                                                  10

                         and were emptied between 0800 and WOO hours dail from 15 February 1986
                         through 30 July 1986 (including holidays and weekends). A drop screen,
                         of identical mesh as the traps, was lowered in front of each trap to
                         prevent passage of organisms while the trap was being emptied. The
                         entire catch was placed in ice until processing.
                              The catch for each trap was sorted by species. Several species
                         were further sorted into categories as follows;

                                         Blue crab (Callinectes saDidus)
                                                small blue crab (less than 25 mm;
                                                               i.e., not easily sexed)
                                                immature female crab
                                                mature female crab
                                                male crab

                                          Ladyfi@_h (Elops saurus)
                                                leptocephalus
                                                juvenile

                                          Speckled worm eel (MVro-_)his punctatus)
                                                leptocephallis
                                                Juvenile/adult

                              The total number  of individuals and total weight (in grams) taken

                         each (lay were determined for each speci@2s or other category, as de-
                         scribed above; these data were then codecl onto a personal computer in
                         the field lab. Excessively large catches of a species were subsampled
                         by a method described by Herke (1978). Wl-i-n the entire sample was too
                         large to be sorted, subsampling was don@i iit the total catch Level
                         before sorting to species). The subsamole weight and the remainder
                         weight for both techniques were used to estimate the number of each

                         species in the entire ratch.
                              The pond trap daLa were total catches of all organisms retained by
                         the trap and deflectin@,,-screen mesh while emigrating from each P(Ind,
                         thus the total catches were a census of the popualtions. Therefcre, to
                         test the hypothesis "catches of emigrating organisms from the two ponds
                         were equal" required no statistics, because the catches were the
                         statistical (and biological) populations, not samples of the
                         populations. [Most fishery research projects sample once a week or so
                         (at best), and must use statistics to account for the lack of data

                         between sample dates, but this study took complete data from all dates.]

                       Thus, we did not have to estimate data or derive confidence limits

                       because we took the entire populations from each experimental pond.
                           Daily salinity and water temperature readings were taken at the
                       environmental and levee stations for each pond (Fig. 2 and 3). Daily
                       readings at the levee stations and stations A and B in Grand Bayou were

                       taken with a Beckman RS-5-3 meter, and at the environmental stations
                       with a Hydrolab 8000. (Grand Bayou salin4ty data collection began on 4
                       April 1986.) The Hydrolabs also recorded salinity and water temperature
                       once per hour from 17 January 1986 through 30 July 1986. Daily water
                       level readings were taken at the chutes in both ponds and in Grand
                       Bayou. (Grand Bayou water level data collection began on 4 March 1986.)
                       A Leupold-Stevens tide gauge, located at the environmental stations,
                       recorded hourly water level readings in each pond.

                                                      Trawling

                            Trawling was conducted every two weeks from 6 March 1986 through
                       30 July 1986. Two trawling stations were located in each experimental
                       pond and in the control pond (Figs. 1 and 2). The control pond was a
                       natural area not affected by any water-control structure. The stations.
                       were located in each of the three ponds such that two locations were
                       sampled, one near the entrance (e.g., CE - Control Entrance) and another
                       near the back (e.g., WB - West Back) of each pond. Each station was
                       sampled with a 16-foot and a 6-foot trawl. The 16-foot trawl had
                       5/8-inch bar mesh in the body and 1/4-inch bar mesh in the cod end, and
                       was towed for 5 minutes (approximate distance of 1/4 mile) with 75-foot
                       ropes from an airboat. The 6-foot trawl had 5/16-inch bar mesh in the
                       body and 3/16-inch bar mesh in the cod end, and was pushed in front of
                       the airboat for 5 minutes (approximate distance of 1/4 mile) along the
                       shoreline as described by Rogers (1985). Trawl samples were processed
                       in the same manner as the trap samples. Salinity and water temperature

                       were measured before each trawl haul with the Beckman instrument.

                                                     Data Analysis
                            This study was designed to encompass, as much as practical, the
                       seasonal presence of brown shrimp in the marsh. The marsh nursery
                       cycles of the many other important species were not entirely covered by

                                                                                             12

                      the study. Consequently discussions for these species are presented in
                      much less detail than for brown shrimp, which was the target species of
                      this study.
                          To compare the total catch between the two ponds, percent change in
                      catch and biomass of organisms emigrating from the slotted-weir pond as
                      compared to the same from the standard-weir pond was calculated as

                      follows:
                       where    Percent Change = ((SLW/STW)-I) X 100

                               SLW = total catch or biomass taken in the slotted-weir pond
                               STW = total catch or biomass taken in the standard-weir pond
                      This formula essentially sets the catch in the standard-weir pond to
                      100%. For example, a percent change of 50 would indicate an increase in
                      catch of 50% from the slotted-weir pond compared to the standard-weir
                      pond, referred to as a 50 percent Increase. A percent change of -50
                      would indicate a 50% decrease in catch from the slotted-weir pond
                      compared to the standard-weir pond, referred to as a 50 percent

                      decrease.

                           For most graphic and tabular presentation, the trawl data were
                      combined (trawls and stations) for each pond by date.. Brown shrimp
                      trawl catch was analyzed by analysis of variance with a split-plot
                      (split on gear) arrangement of treatments (PROC GLM, SAS 1985). Pond,
                      location (entrance or back), and date were the main effects and date was
                      further examined by its linear (D), quadratic (D*D), and cubic (D*D*D)

                      components.

                                                                                                 13

                                                RESULTS AND DISCUSSION

                                                        Brown Shrimp
                              Since the fishery data were collected for only 5.5 months (15
                         February 1986 - 30 July 1986), total comparison of the function of the
                         two structures for all species is impossible, because some of the
                         species had not completed their yearly cycling in and out of the marsh
                         nursery. The structures were installed on 20 December 1985 (2 months
                         before sampling began), thus the fishery data collected should reflect
                         what happened during the study period, there being little influence of
                         the initial installation of the structures. Of the most recreationally
                         and commercially important species, some gulf menhaden and Atlantic
                         croaker individuals may have entered the pond before the structures were
                         installed (Rogers and Herke 1985a). Brown shrimp would have begun the
                         marsh part of their life cycle after the structures were installed, and
                         would have basically finished the majority of the marsh part of their
                         life cycle before the study ended (Rogers and Herke 1985a).
                              The trap data revealed that brown shrimp catches from the slotted
                         weir pond were 241% greater in numbers and 84% greater in biomass than
                         from the standard-weir pond (Table 1). This increased catch from the
                         slotted-weir pond was consistent throughout the study (Fig. 5). Brown
                         shrimp emigration began about 3 weeks earlier in the slotted-weir pond
                         (Fig. 5) and appears to be related to the lunar or tidal phases as noted
                         by (Herke et al. 1987b). The mean weight of brown shrimp at.emigration
                         was consistently greater in the standard-weir pond over time (Fig. 5)
                         and when all shrimp weights were averaged (Table 2).
                              Brown shrimp trawling data contributed additional information.
                         Analysis of variance (PROC GLM, SAS 1985) using a split-plot (split on
                         gear) arrangement of treatments was conducted (Appendix Table 1). The
                         analysis indicated a highly significant difference due to the pond main
                         effect (P < 0.01) but, significant interactions with date [particularly
                         for the quadratic (P < 0.0001) and cubic (P < 0.0248) components]
                         precludes a simple interpretation about the pond catch differences.
                         Essentially, the catch in the three ponds varied differently in relation
                         to one another over time.    Even though the control pond was more

                                                                                                                            14

                                          Table 1. Trap catch, biomass, and percent change for both experimental ponds.

                                                                   NUMBER                             BIOMASS (G)
                                                      ------------------------------  I    -------------------------------
                           SPECIES                    STANDARD      SLOTTED     PERCENT    STANDARD       SLOTTED     PERCENT
                                                        WEIR         WEIR       CHANGE       WEIR           WEIR       CHANGE

                           grass shrimp               270,907       388,977       44       133,995        141,183          5
                           gulf menhaden              219,279       279,171       27       297,798        207,805       -30
                           brown shrimp                28,681       97,694       241       244,536        449,176        84
                           Atlantic croaker            22,193       34,176        54       236,704        170,484       -28
                           white mullet                15,902       21,773        37       167,052        109,461       -34
                           inland silverside           13,451       36,766       173        15,144         30,441       101
                           immature female crab         9,018       28,364       215       318,847        504,321        58
                           male blue crab               8,689       24,874       186       672,912       1,152,386       71
                           gulf killifish               6,350       11,988        89        28,880         51,509        78
                           diamond.killifish            4,327        3,890       -10         2,032          1,600       -21
                           spot                         4,045       15,805       291        32,784         49,471        51
                           striped mullet               3,560       12,921       263        38,391        666,024      1635
                           sheepshead minnow            3,540        7,464       ill         4,917         10,501       114
                           sailfin molly                3,165        1,495       -53         3,750          1,868       -50
                           naked goby                   1,859        2,071        11         1,187          1,388        17
                           bay anchovy                  1,614        1,970        22         2,395          2,202        -8
                           darter goby                  1,116        2,223        99         1,075          1,899        77
                           pinfish                        529        6,115      1056         8,717         63,663       630
                           blue crab (less than 25 mm)    472        6,576      1293           274          2,594       846
                           mature fem ale crab            421          349       -17        74,419         60,483       -19
                           white shrimp                   368        2,2Z2       504           552          8,886      1511
                           rainwater killifish            Z74        1,013       270           196             685      250
                           speckled worm eel              115           72       -37         1,267             821      -35
                           blackcheek tonguefish          112          300       168         1,417          2,660        88
                           bayou killifish                108           83       -23           130             106      -18
                           bay whiff                       76          532       600           911          4,902       438
                           mosquitofish                    70           38       -46            34              22      -37
                           clown goby                      58           41       -29            63              35      -45
                           mud crab                        43           25       -42              7              6       -9
                           ladyfish                        38           49        @q           432             224      -48
                           sharptail goby                  30          390      1200           515          5,666      1000
                           sand seatrout                   18           37       106           484             759       57
                           southern flounder               13          115       785         5,636         14,976       166
                           black drum                       5             5         0           23              26       17
                           rough silverside                 5             1      -80              9              1      -85
                           redea sunfish                    4             6       50            36              44       25
                           longnose killifish               3             2      -33            46               7      -86
                           sheepshead                       3             4       33            57              14      -74
                           red drum                         2           18       800           225          3,953      1660
                           least puffer                     2           49      2350              2             82     3627

                                                                                                                              15

                                            Table 1. continued.

                                                                   NUMBER                             BIOMASS (G)

                                                        ------------------------------       --------------------------------

                             SPECIES                    STANDARD     SLOTTED    PERCENT     STANDARD        SLOTTED     PERCENT
                                                           WEIR         WEIR     CHANGE        WEIR           WEIR       CHANGE

                             violet goby                      2            1       -50           255            76        -70
                             Atlantic cu@lassfish             2            1       -50           228            61        -73
                             green goby                       2            9       350            1               3        93
                             threadfin shad                   1            1         0            4               2       -39
                             fiddler crab                     1                                   2
                             spotted seatrout                              2                                    21
                             silver perch                                  3                                    15
                             Atlantic midshipman                           1                                      3
                             crevalle jack                                 1                                      2
                             hardhead catfish                              7                                  1,389
                             leatherjacket                                 2                                      1
                             inshore lizard fish                           1                                    55
                             bluefish                                      3                                      2
                             gizzard shad                                  5                                    46
                             snapping shrimp                               1                                      2
                             Atlantic spadefish                            1                                    17
                             bluegill                                      1                                      5
                             pipefish                                      21                                   26
                             squid                                         .3                                   79
                             worm eel  leptocephalus                       2                                    40
                             fat sleeper                                   1                                      5

                                                        620,473       989,731        60    2,298,341      3,724,187        62

                              1
                               Percent change is calculated by    ((slotted-weir catch    standard-weir  catch) - 1) x 100.

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                                                                   DATE SET

                                 POND         --------   SLOTTED WEIR           STANDARD WEIR
                                                               ,/V-1111

                         Figure 5.   Number,  biomass, and mean weight of brown shrimp taken by
                                     the traps in each pond.

                                                                                                                                17

                                         Table 2 . Mean weight in gram-, and percent change, of an
                                            individual organism taken by the traps. Values are computed for
                                           those species that had a total catch of 50 or greater in each
                                            experimental pond.

                                                SPECIES                     STANDARD     SLOTTED     PERCENT
                                                                              WEIR         WEIR       CHANGE

                                                mature female crab            176.8        173.3          -2
                                                southern flounder                          130.2
                                                striped mullet                10.8         51.5         378
                                                male blue crab                77.4         46.3         -40
                                                immature female crab          35.4         17.8         -50
                                                sharptail goby                             14.5
                                                speckled worm eel             11.0         11.4           3
                                                pinfish                       16.5         10.4         -37
                                                bay whiff                     12.0          9.2         -23
                                                blackcheek tonguefish         12.7          8.9         -30
                                                Atlantic croaker              10.7          5.0         -53
                                                white mullet                  10.5          5.0         -52
                                                brown shrimp                   8.5          4.6         -46
                                                gulf killifish                 4.5          4.3           -6
                                                white shrimp                   1.5          4.0         167
                                                spot                           8.1          3.1         -61
                                                sheepshead minnow              1.4          1.4           1
                                                bayou killifish                1.2          1.3           6
                                                sailfin molly                  1.2          1.2           5
                                                bay anchovy                    1.5          1.1         -25
                                                darter goby                    1.0          0.9         -11
                                                inland silverside              1.1          0.8         -26
                                                gulf menhaden                  1.4          0.7         -45
                                                rainwater killifish            0.7          0.7           -5
                                                naked goby                     0.6          0.7           5
                                                diamond killifish              0.5          0.4         -12
                                                blue crab (less than Z5 mm)    0.6          0.4         -32
                                                grass shrimp                   0.5          0.4         -27
                                                mosquitofish                   0.5
                                                clown goby                     1.1

                                          I Values in this column are rounded from calculations carried to
                                      Lliree decimal places.

                                                                                              18

                        distant from the Gulf, the brown shrimp appeared earlier and in greater
                        abundance in the control pond than in the two experimental ponds (Fig.
                        6). The control pond was not affected by water-control structures,
                        suggesting that the two experimental structures delayed and reduced
                        recruitment and subsequent standing crops. Even though trap catch from
                        the slotted-weir pond was 2.4 times that from the standard-weir pond,
                        the standing stock trawl estimates for the two experimen'tal ponds were
                        similar in numbers (Fig. 6). This clearly illustrates what was pointed
                        out in the Introduction: two areas may have equal standing stock, yet
                        one may have much higher productivity if its turnover rate is faster.
                           The standing stock biomass was greatest in the standard-weir pond
                        in the latter part of the study (Fig. 6). This was mainly due to the
                        larger shrimp in the standard-weir pond, and was probably a result of
                        delayed emigration from that pond, as noted by Herke et al. (1987b).
                        The biomass peaked earliest in the control pond, again indicating that
                        both structures delayed immigration.
                           The mean weight of brown shrimp from trawl catches was highest and
                        had the greatest increase with time in the standard-weir pond, was
                        intermediate for the slotted-weir pond, mean weight was the lowest and
                        had the least increase with time in the control pond (Fig. 6). Trap
                        catch in the slotted-weir pond was 241% higher than in the standard-weir
                        pond (Table 1); standing crops in the two ponds were similar (Fig. 6)
                        and total trawl catch in the slotted-weir pond was only 32% greater than
                        in the standard-weir pond (Table 3). The only logical conclusion is
                        that brown shrimp were cycling in and out of the slotted-weir pond in
                        less time than the standard-weir pond. Therefore, the greater mean
                        weight and greater increase with time in the standard-weir pond must
                        have been due primarily to a greater delay in emigration from that pond.
                        This resulted in older, and thus larger, shrimp being caught. This
                        conclusion agrees well with a brown shrimp mark and recapture study
                        conducted by Herke et al. (1987b), who reported that brown shrimp were
                        delayed by two weeks on the average from leaving a pond with a weir as
                        compared to a pond with no water-control structure. The measures of
                        standing crop in numbers (Fig. 6) were considerably higher from the
                        control pond, whereas the mean shrimp weight taken in the control pond

                             1,000-                 A
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                                 15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
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                                                                DATE

                        POND              CONTROL      ----- SLOTTED WEIR             STANDARD WEIR

                      Figure 6. Number, biomass, and mean weight of brown shrimp taken by the
                                  trawls in each pond.

                                                                                                                          20
                                     Table 3. Number and biomass taken by both trawls in the three ponds.

                                                   ------------   NUMBER ------------     -----------   BIOMASS  ----------

                          SPECIES                    STANDARD     SLOTTED     CONTROL     STANDARD      SLOTTED    CONTROL
                                                        WEIR         WEIR                   WEIR         WEIR

                          grass shrimp                 29,583     53,898      18,247        4,083        8,788       3,727
                          gulf menhaden                 6,444     10,389      51,047        3,560        6,428       23,494
                          inland silverside             5,753      6,489       4,509        4,355        4,090       2,860
                          spot                          1,005      2,590       8,026        4,465        6,999       13,078
                          white shrimp                    440      1,341       2,596        1,192        2,153
                          Atlantic croaker                919      1,193       1,190        5,229        3,978       3,311
                          brown shrimp                    879      1,162       4,050        5,615        3,688       3,881
                          pinfish                         477         665         249       4,498        5,277       2,085
                          bay anchovy                     837         641      5,821           750         553       1,931
                          rainwater killifish             160         521         736          81          235         349
                          striped mullet                  548         312         201          813       2,058       2,163
                          immature female crab            136         197          35       1,959        1,962         667
                          male blue crab                  146         181          36       5,090        3,235       1,250
                          naked goby                      183         157          38          107          55          20
                          gulf killifish                     20          45        14          62          145          59
                          sheepshead minnow                  31          42        26          25           41          36
                          diamond killifish                  46          27          1         18           13            1
                          clown goby                         20          25          1         21           24            1
                          darter goby                        16          22          5         13              7          3
                          blue crab (lesss than 25 mm)       23          20        32            9          10            9
                          ladyfish                           9           13          2         28              6        92
                          sailfin molly                      77          12        16          45           13          11
                          white mullet                       22          7         21          84           81         200
                          southern flounder                              6         20                      292         119
                          mud crab                                       5         23                          1        11
                          mosquitofish                       6           3           7           3             i          1
                          blackchee-k tonguefish                         3           1                      33          11
                          least puffer                                   2           5                         8        10
                          spotted seatrout,                  1           1           2         43           21            3
                          bay whiff                                      1           1                         1          1
                          pipefish                           16          1           9         18              1          8
                          ladyfish leptocephalus             4           1         69            0             0          7
                          sand seatrout                                            17                                  100
                          red drum                                                   2                                  81
                          silver perch                                               2                                  19
                          black drum                                                 2                                 532
                          crevalle jack                                            11                                   44
                          hardhead catfish                                           2                                  31
                          leatherjacket                                              3                                    3
                          inshore lizard fish                                        3                                 186
                          threadfin shad                                             5                                  20
                          gizzard shad                                               1                                  18
                          pigfish                                                    1                                    1
                          scaled sardine                                             1                                    1
                          diamondback terrapin               1                       1         45                      471
                          chain pipefish                                             2                                    9
                          redear sunfish                     2                     10          20                       88
                          green goby                                                 1                                    1
                          sharptail goby                     1                                   1
                          rough silverside                                         28                                   62
                          TOTAL                         47,805    80,072      97,128        42,232       50,199      62,504

    72

                                                                                               21

                       (Fig. 6) was less than from either experimental pond. Therefore, brown
                       shrimp must have cycled in and out of the control pond in the least
                       time, while being retained longer by the slotted weir, and longest by
                       the standard weir. This would explain the apparent discrepancy between
                       the higher standing biomass in the standard-weir pond, but the lowest
                       emigration, and subsequent contribution to the fishery, from that pond.
                             It is difficult to determine, from this study and others in the
                       literature, which of these three regimes would be the best for
                       maximization of brown shrimp production. We hypothesize that a higher
                       abundance of smaller shrimp would be better for the resource than a
                       considerably lower abundance of larger shrimp for several reasons  *
                       First, the greater numbers would allow brown shrimp to more fully
                       utilize the environmental conditions that they may encounter following.
                       the marsh part of their life cycle. For example, if only a few large
                       shrimp survive to return to the bays and offshore, and conditions are
                       unfavorable, the total number (and biomass) surviving would be lower.
                       Second, if more small shrimp leave the marsh, they have the potential to
                       grow in size and.produce several times the total biomass of the fewer
                       larger ones. Third, the total biomass of numerous smaller shrimp
                       leaving the slotted-weir pond was greater than the total biomass of
                       larger but fewer shrimp leaving the adjacent standard-weir pond as seen
                       in Table 1. Thus, there was relatively high survival and high biomass
                       produced by the slotted-weir pond to*continue growth and possibly
                       provide a greater harvest.

                       Brown Shrimp Conclusions

                             1.   The slotted weir allowed more individuals (241% more) and
                                  biomass (84% more) of brown shrimp to emigrate back towards

                                  the Gulf than did the standard weir.

                             2.   Brown shrimp emigrated from the standard-weir pond later, and
                                  at a larger size, than from the slotted-weir pond.
                             3.   Recruitment into the nursery and emigration were delayed and
                                  reduced by both structures, but more so by the standard

                                  weir.

                                                                                               22

                            4.   Both structures reduced the cycling of brown shrimp in  and
                                 out of the marsh nursery with the standard weir reducing it

                                 more.

                            5.   Use of a slotted weir should result in more brown shrimp
                                 production than would use of a standard weir.

                                                    Species Composition

                            The interpretation for this section will only consider the time
                        frame of this study (15 Feb ruary 1986 through 30 July 1986). Except
                        for brown shrimp, this study did not cover the entire marsh portion of
                        the life cycle of most of the species.
                             To provide an indication of relative abundance and biomass of
                        the species to each other, catch and biomass for all trawling and
                        trapping combined are listed in Appendix Table 2, which also lists the
                        common and scientific names for all organisms taken in the study.
                        Appendix Figs. 1 - 29 contain the daily trap and periodic trawl catch,
                        biomass, and mean weight for gulf menhaden, Atlantic croaker, spot,
                        southern flounder, striped mullet, white mullet, grass shrimp, inland
                        silverside, gulf killifish, sheepshead minnow, bay anchovy, blue crab
                        (less than 25 mm), immature female blue crab, male blue crab, and mature

                        female blue crab.

                            There was an overall increase of 60% in numbers of all species
                        combined trapped while emigrating from the slotted-weir pond as
                        compared to the standard-weir pond (Table 1). Of the species taken in
                        enough abundance to*make conclusions, the small blue crabs had the
                        greatest increase in abundance (1293%), with pinfish having the second
                        greatest increase (1056%). Brown shrimp, immature female blue crab,
                        spot, striped mullet, and white shrimp each had increases of over 200%.
                        Mature female blue crab was the only category of economically important
                        species that decreased in abundance in the slotted-weir pond catch
                        relative to the standard-weir pond.
                            There was an overall increase in biomass emigration (62%) from the
                        slotted-weir pond (Table 1). The percent changes in biomass between the
                        two ponds was much less, than it was by numbers, for most of the

                                                                                                 23

                         economically important species. Striped mullet, white shrimp, and small
                         blue crabs had the greatest percent increase in biomass in the
                         slotted-weir pond.
                              For trapping data, almost all estuarine-dependent organisms were
                         larger in the standard-weir pond (Table 2, Appendix Figs 1 - 29), with
                         the exception of white shrimp and striped mullet. However, not enough
                         of the annual nursery cycle was studied to make any firm conclusions for
                         white-shrimp. Emigrating striped mullet were nearly 5 times larger in
                         the slotted-weir pond trap catch than in the standard-weir pond trap

                         catch.

                              The species trapped and the order of their abundances were similar
                         in the two experimental ponds (Table 1).    The order of abundance of the
                         top eight categories were the same, with minor exceptions. Some 57
                         species emigrated from the slotted-weir pond whereas 42 emigrated from
                         the standard-weir pond. A single fiddler crab was the only species
                         taken in the catch from the standard-weir pond that did not occur in the
                         slotted-weir pond. Although not always consistent, the slotted-weir
                         trap generally caught more species on a daily basis (Fig. 7). The
                         slotted-weir pond catch had many more organisms early in the study, but
                         catches were about the same in the later half (Fig. 7). Except on a few
                         occasions, the catch biomass was greater in the slotted-weir pond on a
                         daily basis (Fig. 7).
                              Appendix Table 3 lists the catch and biomass for individual
                         trawling stations. Trawling data did not show the differences between
                         the experimental ponds as well as the trapping data. The number of
                         species, total catch, and biomass were not distinctly different between
                         ponds over time (Fig. 8). However, total catches over the study period
                         from all three ponds did indicate that the slotted-weir and control pond
                         had 67% to 103% greater standing crop in terms of numbers, and a 19% to
                         48% greater standing crop in terms of biomass than the standard-weir
                         pond, respectively (Table 3).
                              These data again demonstrate that standing crop is not an
                         indicator of productivity (as measured by the export from the ponds
                         back towards the Gulf). Standing crop over time was not very different
                         in the two experimental ponds (Fig. 8), nor was overall trawl catch by
                         biomass (Table 3), but export was much greater from the slotted-weir

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                                     POND         --------     SLOTTED WEIR        -           STANDARD   WEIR

                        Figure 7. Number of species, total number of individuals, and                     biomass
                                       of all emigrating species taken by the trap in each
                                       experimental pond.

                                                                                25

                             25'

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                             15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                                     DATE

                      POND ---- CONTROL    ----- SLOTTED WEIR      STANDARD WEIR

                     Figure 8. Number of species, total number of individuals, and biomass
                              of all species taken by both trawls combined in each
                              experimental pond.

                                                                                               26

                        pond by both numbers and biomass as compared to that from the
                        standard-weir pond (Table 1).
                             Total trawl catch of most of the economically important species
                        such as gulf menhaden'. Atlantic croaker, white shrimp, and brown
                        shrimp was greater in the control and slotted-weir ponds than in the
                        standard-weir pond (Table 3).
                             Twenty-seven species were taken by the trawls in the standard-weir
                        pond trawl catch, 29 in the slotted-weir, and 46 in the control pond
                        (Table 3). Trawling indicated little difference in number of species
                        between the two experimental ponds, whereas the trapping data indicated
                        57 species occurred in the slotted-weir pond and 42 in the standard-weir
                        pond. We have no trap data for the control pond, but based on the trawl
                        data, trap catches there would probably have taken more species than
                        taken emigrating from the ponds having either type of weir. Trends in
                        mean weight are presented in Appendix Figs. 1 - 29 and mean weight of
                        organisms captured by the trawls over the entire study are presented in

                        Table 4.

                        Species Composition Conclusions
                             1.   More organisms (60%) and more biomass (62%) emigrated from
                                  the slotted-weir pond than the standard-weir pond during the
                                  study period.
                             2.   More species emigrated from the slotted-weir pond (57) than
                                  from the standard-weir pond (42) during the study period.
                             3.   The order of species abundance was similar between the two
                                  ponds for the study period.
                             4.   Except for striped mullet, which were approximately five times
                                  larger in the slotted-weir pond, most economically-important
                                  species had a lower mean weight when emigrating from the
                                  slotted-weir pond than from the standard-weir pond for the
                                  study period.
                             5.   Total trawl catch was higher in the control and slotted-weir
                                  ponds than in the standard-weir pond for the study period.
                             6.   More species were taken by the trawls in the control pond (46)
                                  as compared to the slotted-weir (29) and standard-weir (27)
                                  ponds for the study period.

                                                                                                                              27

                                    Table 4. Mean weight (grams) of organisms derived from the combined catch
                                        from both trawls for the duration of the study. Values are computed
                                        for those species which had a total catch of 10 or greater. Species
                                        that were not taken in more than one pond are not included.

                                               SPECIES                    STANDARD     SLOTTED     CONTROL
                                                                              WEIR        WEIR

                                               male blue crab                 34.9        17.9       34.7
                                               immature female crab           14.4        10.0       19.1
                                               pinfish                        9.4         7.9         8.4
                                               striped mullet                 1.5         6.6        10.8
                                               gulf killifish                 3.1         3.2         4.2
                                               brown shrimp                   6.4         3.2         1.0
                                               Atlantic croaker               5.7         3.1         2.8
                                               spot                           4.4         2.7         1.6
                                               white shrimp                   2.7         1.6         0.6
                                               sailfin molly                  0.6         1.1         0.7
                                               sheepshead minnow              0.8         1.0         1.4
                                               clown goby                     1.1         1.0
                                               bay anchovy                    0.9         0.9         0.3
                                               gulf menhaden                  0.6         0.6         0.5
                                               inland silverside              0.8         0.6         0.6
                                               rainwater killifish            0.5         0.5         0.5
                                               diamond killifish              0.4         0.5
                                               blue crab (less than 25 mm)    0.4         0.5         0.3
                                               naked goby                     0.6         0.4         0.5
                                               darter goby                    0.8         0.3
                                               grass shrimp                   0.1         0.2         0.2
                                               white mullet                   3.8                     9.5

                                                                                              28

                                                     Environmental

                        Salinity
                             Salinity readings were taken in the experimental ponds at three
                        locations; the environmental stations (just pondward of the chutes),
                        the levee station, and the trawling stations (Figs. 2 and 3). The
                        salinities taken at the environmental stations did not represent the
                        salinity of the entire ponds, especially when the current was incoming.
                        The salinities taken during trawling were more representative of the
                        entire pond because they were taken at different locations within each
                        pond. The levee station was approximately at the midpoint of the middle
                        levee, and readings there nearly equaled the readings of the trawl
                        stations on the days when trawl samples were taken (Fig. 9) and were
                        thus used to represent the experimental pond salinities. Hourly
                        salinity values taken by the Hydrolab instruments (located at the
                        environmental stations) from 17 January 1986 through 30 July 1986 are
                        presented in Appendix Figure 30.
                             No statistical difference was detected between the two Grand Bayou
                        salinity stations (P = 0.76, PROC GLM, SAS Institute 1985), thus the
                        averages of these two readings were used to represent the Grand Bayou
                        salinity. Hereafter, any reference to the Grand Bayou salinity will
                        be to the daily average of sa linity at stations A and B.
                             The salinity in the slotted-weir pond was approximately 1-3 ppt
                        higher than in-the standard-weir pond for the first two months of the
                        study (Fig. 10). (The structures were in place  approximately two
                        months prior to the beginning of the study, thus the observed
                        differences early in the study were probably due to the structures.)
                        The bottom of the slotted-weir pond had an approximate 0.3-foot higher
                        elevation than the standard-weir pond. Thus, the slotted-weir pond
                        .volume was 23 percent less than the standard-weir pond volume when the
                        water levels were at the weir crest level in the ponds. The resultant
                        lower volume in the slotted-weir pond may account for the increase in
                        salinity (1-3 ppt) in that pond early in'the study. In addition, if the
                        volumes were the same, the expected differences in salinity and water
                        level would be considerably less than seen in this study.
                             The higher the water levels in the ponds and Grand Bayou increased

                       251                                                                             29

                       20

                    CL
                       15

                    z
                    'D 10
                    V)

                         5     ENVIRONMENTAL                                STANDARD WEIR
                               LEVEE          -------
                               TRAWL

                         01
                         15FEB 02MAR 17MAR 01APR    16APR 01MAY 16MAY 31MAY 15JUN 30JUN       15JUL 30JUL
                       251

                       20

                    a-
                    a_

                       10

                    V)

                         5-1
                               ENVIRONMENTAL                                SLOTTED WEIR
                               LEVEE          -------
                               TRAWL

                         01 ...  I-

                         15FEB 02MAR 17MAR 0.1APR  16APR 01MAY 16MAY 31MAY 15JUN 30JUN       1 5JUL 30JUL
                                                              DATE

                         Figure 9. Daily salinity readings taken at the enviroranental and
                                  levee stations, and the mean salinity taken at the trawling
                                  stations, for both experimental ponds.

                      mom noun 4010011w@ on w'.00 sweava mom

                       25'

                              STANDARD WEIR

                              SLOTTED WEIR     --------

                              GRAND BAYOU
                       20"

                    q- 15-

                       10,
                    (A

                         5"

                         01

                         15FEB    02MAR      17MAR      01APR     16APR      01 MAY    16MAY      31 MAY     15JUN     30JUN      1 5JUL    30JUL

                                                                                  DATE

                                  Figure 10.    Salinity in both ponds (as measured at the levee stations) and in Grand
                                                Bayou (average of stations A and B).

                                                                                              31

                       above the weir crest level the more similar both ponds became in terms
                       of salinity and water level (Figs. 10 and 11). To compare salinities
                       for the different locations, the data were separated by concurrent time
                       periods (Table 5). (In Grand Bayou, salinity readings began on 4 April
                       1986 and water level readings began on 4 March 1986.) Over the entire
                       study period, the slotted-weir pond salinity had a lower standard
                       deviation than the standard-weir pond. The standard-weir pond had lower
                       salinities (which deviated greatly from its mean) in the early part of
                       the study, which accounted for this greater overall deviation. When
                       examining data from 4 April through 30 July 1986, Grand Bayou, the
                       slotted-weir pond and the standard-weir pond had decreasing standard
                       deviations, respectively (Table 5). Salinity taken with trawling
                       indicated that the control pond had the highest standard deviation in
                       salinity and the slotted-weir pond had the lowest. Salinities over the
                       entire year, if not more than one year, would be needed to make any firm
                       conclusions on how these structures affect the salinity regime.

                       Water Level

                           The ability to control water levels is of major concern to most
                       marsh managers. Two strong cold front's lowered the water level in
                       Grand Bayou to -14 inches (0'inches = marsh level) early in the study
                       (Fig. 11, Table 5). The water levels in the slotted-weir pond dropped
                       to a minimum of -8 and -9 inches on these two occasions, whereas the
                       water levels dropped to -5 and -5.5 inches in the standard-weir pond
                       (Fig. 11). If the weir crests in both ponds were to the scale that is
                       normally used (1 foot of weir crest per 70 acres of marsh), then water
                       levels would not have dropped as low in either pond. When the water
                       levels dropped in Grand Bayou, the lowest water levels were reached in
                       the slotted-weir pond before the standard-weir.pond. As the water
                       levels rose, the water level in the slotted-weir pond began to rise
                       while the levels were still dropping in the standard-weir pond. Thus
                       for these frontal periods, the slotted-weir would have greater periods
                       of incoming current (traded off with a shorter period of water level
                       decrease), which would allow a greater period of time for larval and/or
                       juvenile organisms to enter the pond. When Grand Bayou water levels
                       were above -6 inches, the pond levels were usually similar. During

                                       10         STANDARD WEIR

                                                  SLOTTED WEIR                  --------

                                                  GRAND BAYOU

                                         5'

                                Li
                                2:
                                                                                  MARSH LEVEL

                                %-oo
                                z
                                                                                                                                                                                        V

                                LAJ
                                >
                                Ld

                                                                                                                 ir I,-
                                                                                              1,V I
                                                                                        y
                                    -10                          11               1     1
                                                                                                                                     WEIR CREST

                                    -15
                                                                                                                                                                 @c vi@

                                         15FEB            02MAR             17MAR            01APR             16APR             0 1 MAY           16MAY            31 MAY            I SJUN            30JUN             15JUL             30JUL
                                                                                                                                     .    DATE

                                                           Figure 11. Water                   level for the experimental ponds and Grand Bayou.

                                                                                                                              33

                           Table 5. Summary statistics for the daily physical measurements for the experimental ponds
                                      (at the levee station) and Grand Bayou, and physical data collected while trawling in
                                      the three ponds. Data are separated by time frames such that valid comparisons can be
                                      made. Water levels are presented in inches, with 0 inches being equal to marsh level.

                                                N                       STANDARD        STD ERROR          MINIMUM          MAXIMUM
                             POND           (SAMPLES)     MEAN          DEVIATION        OF MEAN           VALUE            VALUE

                                                                          15 FEBRUARY - 30 JULY 1987
                                            --------------------------------    SALINITY (ppt)     -------------------------------
                           SLOTTED            165            16.6             2.2              0.2             9.1            20.7
                           STANDARD           165            14.9             3.0              0.2             7.8            20.4

                                            ------------------------------   WATER TEMPERATURE (C)    ----------------------------
                           SLOTTED            165            23.6             5.2              0.4             8.1            34.7
                           STANDARD           164            23.5             5.3              0.4             7.1            33.7

                                            --------------------------------    WATER LEVEL (in)   ------------------------------
                           SLOTTED            165            -1.7             3.6              0.3            -9.0             6.0
                           STANDARD           165            -1.1             2.9              0.2            -5.8             6.0

                                                                           4 MARCH - 30 JULY   1987
                                            --------------------------------   WATER LEVEL (in)    -------------------------------
                           GRAND BAYOU        148            -2.5             4.2              0.3            -14.3            6.8
                           SLOTTED            148            -1.4             3.6              0.3            -9.0             6.0
                           STANDARD           148            -0.8             3.0              0.2            -5.8             6.0

                                                                           4 APRIL - 30 JULY   1987
                                            --------------------------------    SALINITY (ppt)     -------------------------------
                           GRAND BAYOU        117            17.1             2.4              0.2            11.7            21.0
                           SLOTTED            117            17.4             1.8              0.2            14.4            20.7
                           STANDARD           117            16.6             1.4              0.1            13.7            20.4

                                            ------------------------------   WATER TEMPERATURE (C)    ----------------------------
                           GRAND BAYOU        117            26.4             3.6              0.3            17.7            32.3
                           SLOTTED            117            26.0             3.5              0.3            16.0            34.7
                           STANDARD           117            26.0             3.5              0.3            16.2            33.7

                                                                                TRAWLING DATA

                                            --------------------------------    SALINITY (ppt)     -------------------------------
                           CONTROL             48            16.2             2.9              0.4             9.1            20.6
                           SLOTTED             48            16.8             2.3              0.3            12.2            20.3
                           STANDARD            48            15.3             2.8              0.4             9.1            20.0

                                            -----------------------------    WATER TEMPERATURE (C)   -----------------------------
                           CONTROL             48            28.3             5.3              0.8            18.0            38.3
                           SLOTTED             48            27.0             4.6              0.7            17.8            35.8
                           STANDARD            48            26.8             4.7              0.7            18.2            35.6

                                                                                                34

                        extremely low water levels in March, the slotted weir buffered water
                        level changes in range and time as compared to Grand Bayou (Figure 11),
                        but not as much as the standard weir. The short-term drops in water
                        levels from April through July were buffered about the same by both
                        structures. The water levels were slightly more variable over the
                        entire study in the slotted-weir pond than in the standard -weir pond
                        (Table 5). Apparently, as overall water level increased above crest
                        levels, both structures exhibited about the same water level
                        characteristics and only when water levels declined to near crest level

                        did the two structures differ in their water level characteristics.

                        Appendix Figure 31 contains hourly water level values taken by the
                        Leupold-Stevens gauges from 17 January 1986 through 30 July 1986.

                        Water Temperature
                             No"statistical difference was detected between Stations A and B in
                        Grand Bayou (P = 0.92, PROC GLM, SAS Institute 1985). No obvious
                        differences in water temperature were noticed between the two
                        experimen@al ponds (Table 5, Appendix Fig. 32) at the levee stations.

                        Environmental Conclusions

                             1.   Both structures reduced the salinity changes, when compared to
                                  Grand Bayou, with the slotted-weir pond having the lower
                                  standard deviation than the standard-weir pond for the overall
                                  study period (even though the slotted-weir pond had 23% less
                                  volume). Data should be collected from all times of one or
                                  more years to make firm conclusions on the effect these two
                                  structures have on the salinity regime.
                             2.   As Grand Bayou water levels increased above the weir crest
                                  level, the experimental ponds became more similar in water
                                  level and salinity for this study period at least.
                             3.   Water levels in the slotted-weir pond were 3 to 4 inches
                                  lo,wer than the standard-weir pond when water levels were
                                  extremely low in Grand Bayou (-14 inches), but similar
                                  between the experimental ponds when water levels were

                                  above the weir crest.

                                                                                               35

                             4.   No obvious differences in water temperatures were detected
                                  between the two experimental ponds and Grand Bayou for the
                                  study period.

                                                                                            36

                                                GENERAL DISCUSSION

                          Each marsh management situation may differ in terms of the marsh
                      type, location relative to the Gulf, desired resource use, and funds
                      avaifable for management. Any type of marsh management will require
                      a trade off of time, money, and certain natural resources.
                      Historically, weirs have been installed primarily to maintain minimum
                      water levels for human access and improve habitat for waterfowl and
                      furbearers. Recently these weirs have been recommended to reduce
                      saltwater intrusion and erosion (DaV4s and Gagliano 1983). There is
                      no direct evidence that weirs reduce erosion, and only in certain
                      hydrological situations do they reduce saltwater intrusion. Herke et
                      al. (1987b) demonstrated the fisheries losses due to weir
                      construction. Chabreck and Hoffpauir (1965), Chabreck (1968), and
                      Wicker et al. (1983) discussed the benefits of weirs to furbearers and
                      waterfowl. Reduced growth of saltmarsh cordgrass in water-logged
                      soils (a condition often found in semi-impounded areas) has been
                      demonstrated by Mendelssohn and Seneca (1980) and Mendelssohn et al.
                      (1980). The resource manager must consider these and possibly other
                      asp ects when making marsh management decisions. Thus, the purpose of
                      this study was to test the effects of a management alternative that
                      would improve estuarine-dependent fisheries production, thereby
                      providing an additional aspect for managerial consideration.
                           The slotted weir allowed the emigration of 241% more brown shrimp
                      and 82% more brown shrimp biomass than the standard weir. Although the
                      complete annual cycle of most other species was not covered by the
                      study, the total catch of all emigrating species was 60% higher (62% by
                      biomass) in the slotted-weir pond. Although the total biomass of
                      emigrants was less, the average size of an economically-important
                      organism (with the major exception of striped mullet) was larger in the
                      standard-weir pond. .
                           Comparison of the results of this study to that of Herke et al.
                      (1987b) allows a look at four structural alternatives, all'monitored
                      at the same study site: standard weir, slotted weir, standard weir set
                      at 12 inches below marsh level, and no structure. The most obvious
                      drawback to the comparison is that the Herke et al. (1987b) data were

                                                                                                37

                         from years other than the present study. Table 6 presents comparative
                         da'ta (15 February through 30 July) on these four structures. It is
                         obvious that the most fisheries export would generally occur with no
                         structure. Comparison of brown shrimp catch by date for the four
                         structures indicates that the absence of a structure allows the greatest
                         emigration, while the standard fixed-crest weir allows the least (Fig.
                         12). Since any type of structure placed in the path of these migrating
                         organisms apparently impedes movement, the objective of this study was

                         to examine an alternative to the fixed-crest weir in the coastal

                         habitat, which would more adequately balance the resource use for all

                         forms of wildlife.
                              The slotted-weir appears to be a compromise (between no weir and a
                         standard weir) for both fisheries and hydrologic balance. The slotted
                         weir apparently yields median results between the control pond (early
                         and abundant immigration, early emigration, low mean size, and high rate
                         of cycling) and the standard weir (later and less abundant immigration,
                         delayed emigration, increasingly greater mean size, and low rate of
                         cycling). Although the hydrologic data in this study only cover parts
                         of the winter and summer regime, it appears the greater discrepancy in
                         hydrology between the ponds would occur in the winter, especially during
                         cold fronts. (A possible management practice may be to close the slot
                         during strong cold fronts.)    The effect of the slotted and standard
                         weir for management of the hydrologic regime should be further studied
                         and should encompass the entire annual cycle.
                              The width of the slot would be subject to management requirements
                         and the hydrodynamics of the area concerned. The widest slot that
                         will still achieve the rest of the management goals would be desired
                         for coastal fisheries benefits. Data from this study can be used as
                         an example, but not necessarily as a model. With these empirical data
                         and knowledge of hydrologic principles, formulas or models could be
                         derived to estimate the slot width for a given area to meet management
                         criteria. The weir crests (see Methods and Procedure) were wider per
                         area of marsh affected than is generally used in practice. Thus, the
                         absolute differences in salinity and water levels between the two
                         experimental ponds in this study probably were greater than would be
                         expected had the marsh area been larger or the weir crests shorter.

                                                                                                    38

                      Table 6. Catch of abundant, or economically-important, organisms taken
                           by Herke et al. (1987b)(15 February 1983 through 30 July 1983) and
                           this study (15 February 1986 through 30 July 1986).

                                               Herke et al. (1987b)                This Study

                                                No      Low Standard  1      Slotted        Standard
                        Species              Structure        Weir              Weir           Weir

                      gulf menhaden            834,045        73,717           2793,171      219,279
                      grass shrimp             324,767        331,871          388,977       270,907
                      brown shrimp             285,954        93,486            97,694         28,681

                      Atlantic croaker         228,296        47,728            34,176         22,193
                      blue crab (< 25 mm)      226,833        151,567            6,576            472
                      bay anchovy              169,771        22,820             1P970         1,614

                      imm. female blue crab     97,968        75,259            28,364         9,018
                      inland silverside         95,648        80,343            36,766         13,451
                      male blue crab            75,711        60,431            24,874         8,689

                      spot                      16,496         9yO22            15,805         4,045
                      striped mullet            10,603        11,484            12y921         3,560
                      gulf killifish             6,181         5,184            11,988         6,350

                      naked goby                 5,998         3,033             2,071         1,'859
                      sheepshead minnow          4,795         2,726             7,464         3,540
                      white mullet               2,141         3,416            21,773         15,902

                      pinfish                      207            155            6,115            529
                      white shrimp                 695             15            2,222            368
                      red drum                     540             80                18             2

                      sand seatrout                490            135                37           18
                      southern flounder              30            12               115           13
                      spotted seatrout                 9            0                 2             0
                      1 Standard weir with crest set    12 inches  below average marsh soil level.

                                                                                                                    39

                               30,000-

                               20,000                                                                 1983
                        U-1
                        M                                                                           ---- NO WEIR
                        :M                                                                          -LOW WEIR
                        D
                        z      10,000.                                      "It,

                                                                                    ;hJ

                                     01-

                                     15APR    30APR     15MAY      30MAY     14JUN     29JUM      14JUL     29JUL

                               30,000-

                                                                                                      1984
                               20,000-
                                                                                                    -----NO WEIR
                        ch
                                                                                                    -LOW WEIR
                        z      10,000

                                                                               It

                                      01         1

                                     15APR    30APR      15MAY     30MAY     14-JUN     29JUN     14JUL     29JUL

                               30,000.

                                                                                                      1986
                        CC     20,000-                                                              ---- SLOTTED WEIR
                        W
                        M                                                                                STANDARD WEIR

                        z      10,000.

                                      01

                                     15APR     30APR     15MAY     30MAY     14-JUN     29JUN     14JUL      29JUL

                                                                        DATE SET

                          Figure 12. Brown shrimp catch for 1983 and           1984 (Herke et al. 1987b)
                                        and 1986 (this study) at the experimental ponds. The weir
                                        crest was set at 12 inches below average marsh soil ground
                                        level in 1983 and 1984.

                                                                                             40

                       Also, the slotted-weir pond had less volume, which should have increased
                       the salinity and water level variability. The length of weir crest,
                       marsh area affected, depth, ratio of marsh to open water, amount of
                       fresh water inflow, and other considerations should be included when
                       calculating the slot width.
                            If a marsh is to be managed by water-control structures, they
                       should be customized to the specific resource needs. A slotted weir
                       may be inappropriate in a fresh or intermediate marsh, because
                       saltwater exclusion may be the primary management goal. Cowan et al.
                       (1986) found that most marsh management practices in the fresh and
                       intermediate marshes were generally successful. However, they concluded
                       marsh management practices in the brackish to saline habitats were, by
                       and large, only marginally successful. Indications are that the
                       brackish and saline marshes may need more water exchange and
                       fluctuations to allow oxidation of the soils and reduce the stress upon
                       the natural plants that dominate that environment.

                            From this study it is evident that, if a weir is considered as a
                       coastal marsh management tool, a slotted weir would be more beneficial

                       to fisheries resources. Additional research should be conducted to
                       determine the compatibility of slotted weirs with management goals which
                       are designed to benefit. other forms of wildlife, and preserve and
                       enhance marsh vegetation. As a minimum, such investigations should:

                            1.   Evaluate the effectiveness of the standard and slotted weir

                                 in reducing erosion and stress on the native plants.
                            2.   Evaluate the effectiveness of these structures in providing

                                 habitat for other forms of wildlife.

                            3.   Further evaluate the effect of these structures on seasonal

                                 salinity patterns and water levels.

                            4.   Evaluate the effect of these structures on other
                                 estuarine-dependent fishes and crustaceans (the target
                                 species for this study was brown shrimp).
                       These evaluations could be done simultaneously to reduce costs. They
                       should also cover enough years (probably 5 to 7) to provide a complete
                       evaluation of the short- and long-term effects of alteration of the
                       hydrologic regime on the marsh vegetation and all forms of wildlife.

                                                                                             41

                       General Conclusion

                            1. The slotted weir allowed greater numbers and biomass of brown
                                shrimp to emigrate back toward the Gulf. Resource managers

                                should consider the slotted weir as an alternative to the

                                standard fixed-crest weir.

                                                                                             42

                                                    CONCLUSIONS

                           The conclusions for each section are reproduced here for
                      convenience of the reader. The study only covered a 5.5 month period
                      (15 February through 30 July), thus these conclusions are based on that
                      period alone. Conclusions for species other than brown shrimp (target
                      species for this study) and hydrologic factors would require a study
                      which at least examines an entire yearly cycle.

                      Brown Shrimp Conclusions
                           1.   The slotted weir allowed more individuals (241% more) and
                                biomass (84% more) of brown shrimp to emigrate back towards

                                the Gulf than did the standard weir.

                           2.   Brown shrimp emigrated from the standard-weir pond later, and
                                at a larger size, than from the slotted-weir pond.
                           3.   Recruitment into the nursery and emigration were delayed and
                                reduced by both str*uctures, but more so by the standard

                                weir.

                           4.   Both structures reduced the cycling of brown shrimp in and
                                out of the marsh nursery with the standard weir reducing it

                                more.

                           5.   Use of a slotted weir should result in more brown shrimp
                                production than would use of a standard weir.

                      Composite Species Conclusions
                           1.   More organisms (60%) and more biomass (62%) emigrated from
                                the slotted-weir pond than the standard-weir pond during the
                                study period.
                           2.   More species emigrated from the slotted-weir pond (57) than
                                from the standard-weir pond (42) during the study period.
                           3.   The order of species abundance was similar between the two
                                ponds for the study period.

                                                                                                43

                             4.   Except for striped mullet, which were approximately 5 times
                                  larger in the slotted-weir pond, most economically-important
                                  species had a lower mean weight when emigrating from the
                                  slotted-weir pond than from the standard-weir pond for the
                                  study period.
                             5.   Total trawl catch was higher in the control and slotted-weir
                                  ponds than in the standard-weir pond for the study period.
                             6.   More species were taken by the trawls in the control pond (46)
                                  as compared to the slotted-weir (29) and standard-weir (27)
                                  ponds for the study period.

                        Environmental Conclusions

                             1.   Both structures reduced the salinity changes, when compared to
                                  Grand Bayou, with the slotted-weir pond having the lower
                                  standard deviation than the standard-weir pond for the overall
                                  study period (even though the slotted-weir pond had 23% less
                                  volume). Data should be collected from all times of one or
                                  more years to make firm conclusions on the effect these two
                                  structures have on the salinity regime.
                             2.   As Grand Bayou water levels increased above the weir crest
                                  level, the more the experimental ponds became similar in water
                                  level and salinity for the study period.
                             3.   Water levels in the slotted-weir pond were 3 to 4 inches
                                  lower than the standard-weir pond when water levels were
                                  extremely low in Grand Bayou (-14 inches), but similar
                                  between the experimental ponds when water levels were

                                  above the weir crest.

                        General Conclusion

                             1. The slotted weir allowed greater numbers and biomass of brown
                                 shrimp to emigrate back toward the Gulf. Resource managers

                                 should consider the slotted weir as an alternative to the

                                 standard fixed-crest weir.

                                                                                              44

                                              LITERATURE CITED

                    Bradshaw W. H. 1985. Relative abundances of small brown shrimp    as
                         influenced by semi-impoundment. M.S. Thesis, Louisiana State
                         University, Baton Rouge. 61 p.

                    Chabreck, R. H. 1968. Weirs, plugs, and artificial potholes for the
                         management of wildlife in coastal marshes. Pages 178-192 in J. D.
                         Newsom editor. Proceedings of the Marsh and Estuary Management
                         Symposium. Division of Continuing Education,, Louisiana State
                         University, Baton Rouge.

                    Chabreck, R. H. and C. M. Hoffpau ir. 1965. The use of weirs in
                         coastal marsh management in Louisiana. Proceedings of the Annual
                         Conference Southeastern Association of Game and Fish Commissioners.
                         16:103-112.

                    Cowan J. H., R. E. Turner, and Donald R. Cahoon. 1986. A preliminary
                         analysis of marsh management plans in coastal Louisiana. Coastal
                         Ecology Institute, Center for Wetland Resources, Louisiana State
                         University, Baton Rouge, Louisiana. Work Assignment 9.

                    Davis, D. J. and S. M. Gagliano. 1983. LaFourche Realty wetlands marsh
                         management program. Coastal Environments, Inc., 1260 Main St.,
                         Baton Rouge, Louisiana. 43 p.

                    Herke, W. H. 1968. Weirs, potholes and fishery management. Pages
                         193-211 in J. D. Newsom, editor. Proceedings of the Marsh and
                         Estuary Management Symposium. Division of Continuing Education,
                         Louisiana State University, Baton Rouge.

                    Herke, W. H. 1971. Use of natural, and semi-impounded, Louisiana tidal
                         marshes as nurseries for fishes and crustaceans. Ph.D.
                         Dissertation, Louisiana State University, Baton Rouge. 264 D.
                         Univ. Microfilms, Ann Arbor, Mich. (Diss. Abs. 32:2654-B).

                    Herke, W. H* 1978* A subsampler for estimating the number and length
                         frequency of small, preserved nektonic organisms. Fisheries
                         Bulletin 76(2):490-494.

                    Herke, W. H. 1979. Some effects of semi-impoundment on coastal
                         Louisiana fish and crustacean nursery usage. Pages 325-346   'in
                         J. W. Day, Jr., D. D. Culley, Jr., R. E. Turner, and A. J.
                         Mumphrey, Jr. editors. Proceedings of the Third Coastal Marsh and
                         Estuary Management Symposium, Division of Continuing Education,
                         Louisiana State University, Baton Rouge.

                    Herke, W. H., B. D. Rogers, and E. E. Knudsen. 1984a. Habits and
                         habitats of young spotted seatrout in Louisiana marshes.
                         Research Report No. 3. School of Forestry, Wildlife, and
                         Fisheries, Louisiana State University, Baton Rouge. 48 p.

                                                                                              45

                    Herke, W. H., B. D. Rogers, and J. A. Grimes. 1984b. A study of the
                         seasonal presence, relative abundance, movements, and use of
                         habitat types by estuarine-dependent fishes and
                         economically-important decapod crustaceans on the Sabine
                         National Wildlife Refuge. Final Report. Louisiana
                         Cooperative Fish and Wildlife Research Unit, Louisiana State
                         University, Baton Rouge. 3 volumes. 933 p.

                    Herke, W. H., E. E. Knudsen,, B. D. Rogers, and V. L. Prenger. 1985.
                         Effects of a fixed-crest water-control structure on the abundance
                         of the fish and crustaceans migrating from a shallow marsh nursery
                         toward the Gulf of Mexico. Estuaries 8(2A):21A.

                    Herke, W. H., M. W. Wengert, and M. E. Lagory. 1987a. Abundance of
                         brown shrimp in a natural and semi-impounded marsh nursery areas:
                         relation to temperature and salinity. Northeast Gulf Science 9(l):
                         In press.

                    Herke, W. H., E. E. Knudsen, Z. X. Chen, N. S. Green, P. A. Knudsen, and
                         B. D. Rogers. 1987b. Final report for the Cameron-Creole
                         Watershed Fisheries Investigations. Louisiana Cooperative Fish and
                         Wildlife Research Unit, School of Forestry, Wildlife, and
                         Fisheries, Louisiana State University Agricultural Center, Baton
                         Rouge. In press.

                    King, B. D., 111. 1971. Study of migratory patterns of fish and
                         shellfish through a natural pass. Texas Parks and Wildilfe
                         Department. Technical Series No. 9. Austin, Texas. 54 p.

                    Mendelssohn, I. A. and E. D. Seneca. 1980. The influence of soil
                         drainage on the growth of salt marsh cordgrass Spartina
                         alterniflora in North Carolina. Estuarine and Coastal Marine
                         Science (1980)11:27-40.

                    Mendelssohn, I. A., K. L. McKee, and W. H. Patrick, Jr. 1980. Oxygen
                         deficiency in Spartina alterniflora roots: metabolic adaptation
                         to anoxia. Science 214:439-441.

                    Perry, W. G. 1981. Seasonal abundance and distribution of brown and
                         white shrimp in a semi-impounded Louisiana coastal marsh.
                         Proceedings of the Louisiana Academy of Science 44:102-111.

                    Rogers, B. D. 1985. A small push-otter trawl for use in shallow
                         marshes. North American Journal of Fishery Management
                         5(3A):411-413.

                    Rogers, B. D. and W. H. Herke. 1985a. Temporal patterns and size
                         characteristics of migrating juvenile fishes and crustaceans in a
                         Louisiana marsh. Research Report No. 5. School of Forestry,
                         Wildlife and Fisheries, Louisiana State University, Baton Rouge.
                         81 P.

                                                                                             46

                   Rogers, B. D. and W. H. Herke. 1985b. Estuarine-dependent fish and
                        crustacean movements and weir management. Pages 210-219 in C. F.
                        Bryan, P. J. Zwank, and R. H. Chabreck, editors. Proceedings of
                        the Fourth Coastal Marsh and Estuary Management Symposium.
                        Louisiana Cooperative Fish and Wildife Research Unit, Louisiana
                        State University, Baton Rouge.

                   SAS Institute Inc. 1985. SAS User's Guide: Statistics. 1985 edition.
                        SAS Institute Inc. Cary, NC. 956p.

                   Schultz, T. S. 1985. Diel movement of brown shrimp (Penaeus aztecus)
                        at a southwest Louisiana estuarine lake-marsh interface. M. S.
                        Thesis, Louisiana State University, Baton Rouge. 93 p.

                   Wicker, K. M., D. Davis, and D. Roberts. 1983. Rockefeller State
                        Wildlife Refuge and Game Preserve: Evaluation of wetland
                        management techniques. Louisiana Department of Natural Resources,
                        Coastal Management Section, Baton Rouge. 86 p, 8 plates.

                   Wengert, M. W., Jr. 1972. Dynamics of the brown shrimp, Penaeus
                        aztecus aztecus Ives 1891, in the estuarine area of Marsh Island,
                        Louisiana in 1971. M.S. Thesis, Louisiana State University, Baton
                        Rouge. 94 p.

                                                                                                                                   47

                                     Appendix Table 1. Analysis of variance (PROC GLM, SAS 1985) for brown shrimp
                                                          (log number + 1) for trawling data. Date is further
                                                          analyzed by its' linear (D), quadratic (D*D), and cubic
                                                          (DytD*D) components.

                                                            GENERAL LINEAR MODELS PROCEDURE

                                     DEPENDENT VARIABLE: log catch + I

                                     SOURCE                   DF    SUM OF SQUARES        F VALUE       PR > F    R-SQUARE
                                                                        (TYPE I)

                                     MODEL                    ill          300.29            9.17         0.0001       0.98

                                       POND                    2           41.34             70.05        0.0001

                                       LOCATION                1             0.02            0.05         0.8229

                                       D                       1             0.02            0.07         0.8004
                                       D*D                     1           91.25            309.26        0.0001
                                       D*D*D                   1             1.74            5.89         0.0248
                                       DATE                    7             6.69            3.24         0.0183
                                       POND*LOCATION           2             0.03            0.05         0.9488
                                       D*POND                  2           67.47            114.34        0.0001
                                       D*D*POND                2             4.33            7.34         0.0041
                                       D*D*D*POND              2             0.44            0.74         0.4907
                                       PONDYcDATE             14           12.78             3.09         0.0106
                                       LOCATIONY-DATE         10             1.86            0.63         0.7718
                                       POND*LOCATION*DATE     20             5.62            0.95         0.5423

                                       GEAR                    1           12.39             41.98        0.0001
                                       POND*GEAR               2             0.59            1.00         0.3870
                                       LOCATION*GEAR           1             0.13            0.46         0.5077
                                       GEAR*DATE              10           29.76             10.09        0.0001  *YC
                                       POND*GEAR*DATE         20           21.71             3.68         0.0027
                                       POND*LOCATION*GEAR      2             0.69            1.13         0.3417
                                       LOCATION*GEAR*DATE     10             1.46            0.50         0.8731

                                     ERROR                    20             5.90

                                     CORRECTED TOTAL          131          306.19

                                                                                                                              48

                              Appendix Table 2. List of all species, catch and biomass for the entire study taken by the
                                                  traps and trawls combined.

                              SCIENTIFIC                        COMMON                                NUMBER          BIOMASS
                                 NAME                           NAME                                                   (G)

                              Palaemonetes sp.                  grass shrimp                          761,612         291,776
                              Brevoortia patronus               gulf menhaden                         566,330         539,085
                              Penaeus aztecus                   brown shrimp                          132,466         706,896
                              Menidia beryllina                 inland silverside                     66,968           56,890
                              Micropogonias undulatus           Atlantic croaker                      59,771          419,705
                              C. sapidus, immature female       im-tu e female blue crab              37,750          827,757
                              Mugil curen-                      white mullet                          37,725          276,877
                              Callinectes sapidus, male         male blue crab                        33,926         1,834,874
                              Leiostomus xanthurus              spot                                  31,471          106,798
                              Fundulus grandis                  gulf  killifish                       18,417           80,655
                              Mugil cephalus                    striped mullet                        17,542          709,449
                              Cyprinodon variegatus             sheepshead minnow                     11,103           15,520
                              Anchoa mitchilli                  bay anchovy                           10,883             7,833
                              Adinia xenica                     diamond killifish                      8,291             3,664
                              Lagodon rhomboides                pinfish                                81035           84,240
                              Callinectes sapidus               blue crab (less than 25 mm)            7,123             2,896
                              Penaeus setiferus                 white shrimp                           6,967           14,220
                              Poecilia latipinna                sailfin molly                          4,765             5,687
                              Gobiosoma bosci                   naked goby                             4,308             2,757
                              Gobionellus boleosoma             darter goby                            3,382             2,998
                              Lucania parva                     rainwater killifish                    2,704             1,546
                              C. sapidus, mature female         mature female blue                       770          134,902
                              Citharichthys spilopterus         bay whiff                                610             5,815
                              Gobionellus hastatus              sharptail goby                           421             6,182
                              Symphurus plagiusa                blackcheek tonguefish                    416             4,121
                              Fundulus pulvereus                bayou killifish                          191               235
                              Myrophis punctatus                speckled worm eel                        187             2,088
                              Paralichthys lethostigma          southern flounder                        154           21,024
                              Microgobius gulosus               clown goby                               145               143
                              Gambusia affinis                  mosquitofish                             124                62
                              Elops saurus                      ladyfish                                 ill               782
                              Rithropanopeus harisii            mud crab                                   96               25
                              Elops saurus leptocephalus        ladyfish leptocephalus                     74                 7
                              Cynoscion arenarius;              sand seatrout                              72            1,344
                              Sphoeroides parvus                least puffer                               58              103
                              Syngnathus sp.                    pipefish                                   47               54
                              Membras martinica                 rough silverside                           34               73
                              Sciaenops ocellatus               red drum                                   22            4,258
                              Lepomis microlophus               redear sunfish                             22              188
                              Pogonias cromis                   black drum                                 12              581
                              Caranx hippos                     crevalle jack                              12               46
                              Microgobius thalassinus           green goby                                 12                 5
                              Arius felis                       hardhead catfish                            9            1,421
                              Dorosoma petenense                threadfin shad                              7               25
                              Archosargus probatocephalus       sheepshead                                  7               71

                                                                                                                              49

                              Appendix Table 2. continued.

                              SCIENTIFIC                        COMMON                                 NUMBER          BIOMASS
                                 NAME '                         NAME                                                    (G)

                              Cynoscion nebulosus               spotted seatrout                           6               88
                              Dorosoma cepedianum               gizzard shad                               6               64
                              Bairdiella chrysoura              silver perch                               5               34
                              Oligoplites saurus                leatherjacket                              5                4
                              Fundulus similis                  longnose killifish                         5               52
                              Synodus foetens                   inshore lizard fish                        4              241
                              Pomatomus saltatrix               bluefish                                   3                2
                              Gobioides broussoneti             violet goby                                3              331
                              Trichiurus lepturus               Atlantic cutlassfish                       3              290
                              Malaclemys terrapin               diamondback terrapin                       2              516
                              Syngnathus louisianae             chain pipefish                             2                9
                              M. punctatus leptocephalus        worm eel leptocephalus                     2               40
                              Porichthys plectrodon             Atlantic midshipman                        1                3
                              Orthopristis chrysoptera          pigfish                                    1                1
                              Alpheus sp.                       snapping shrimp                            1                2
                              Uca sp.                           fiddler crab                               1                2
                              Harengula jaguana                 scaled sardine                             1                1
                              Chaetodipterus faber              Atlantic spadefish                         1               17
                              Lepomis macrochirus               bluegill                                   1                5
                              Dormitator maculatus              fat sleeper                                1                5
                              TOTAL                                                                 1,835,209        6,177,464

                                                                                                                                                        50

                             Appendix Table 3. List of species, total catch, and total biomass for trawling data by
                                                      station and gear for the entire study.

                                   Station WB (standard-weir, back -     six-foot trawl)          Station WB (standard-weir, back - sixteen-foot trawl)

                                     SPECIES                      NUMBER    BIOMASS (g)                 SPECIES                   NUMBER    BIOMASS (g)

                                     grass shrimp                 18,854        2,121                   gulf menhaden             1,114         1,011
                                     gulf menhaden                2,300           733                   Atlantic croaker            482         2,474
                                     inland silverside            2,136         1,578                   brown shrimp                388         3,008
                                     striped mullet                     499       380                   spot                        340         1,736
                                     spot                               256       390                   inland silverside           324           294
                                     bay anchovy                        229       166                   grass shrimp                261              63
                                     naked goby                         129          68                 white shrimp                197           851
                                     rainwater killifish                122          60                 bay anchovy                 192           168
                                     white shrimp                       114       101                   pinfish                     181         1,864
                                     brown shrimp                       87        244                   male blue crab               76         2,920
                                     pinfish                            73           26                 inunature female crab        72         1,014
                                     sailfin molly                      45           27                 white mullet                   4             37
                                     immature female crab               26        302                   striped mullet                 3          301
                                     diamond killifish                  24           10                 blue crab (less than   25mm)   3             1
                                     sheepshead minnow                  23           22                 naked goby                     3             4
                                     male blue crab                     22        230                   darter goby                    2             2
                                     blue crab (less than 25 mm)        14           5                  clown goby                     2             3
                                     gulf killifish                     13           46                 ladyfish                       2             16
                                     white mullet                       12           14                 pipefish                       1             1
                                     pipef ish                          12           14                 TOTAL                     3,647         15,771
                                     Atlantic croaker                   7            33
                                     clown goby                         7            8
                                     mosquitofish                       5            3
                                     ladyfish                           5            1
                                     darter goby                        3            3
                                     ladyfish leptocephalus             3            0
                                     diamondback terrapin               1            45
                                     redear sunfish                     1            6
                                     sharptail goby                     1            1
                                     TOTAL                        25,023        6,634

                                   Station WM (standard-weir,     mouth   six-foot trawl)         Station WM (standard-weir. mouth - sixteen-foot trawl)

                                     SPECIES                      NUMBER     BIOMASS                    SPECIES                   NUMBER     BIOMASS (g)

                                     grass shrimp                 10,203        1,833                   gulf menhaden             2,512         1,640
                                     inland silverside            2,589         1,842                   inland silverside           704           640
                                     gulf menhaden                      518       176                   Atlantic croaker            422         2,714
                                     bay anchovy                        213       204                   spot                        363         2,231
                                     brown shrimp                       127       230                   brown shrimp                277         2,133
                                     naked goby                         50           34                 grass shrimp                265              65
                                     white shrimp                       49           17                 bay anchovy                 203           212
                                     Spot                               46        108                   pinfish                     186         2,592
                                     striped mullet                     44           55                 white shrimp                 80           223
                                     rainwater killifish                37           20                 male blue crab               38         1,862
                                     pinfish                            37           16                 immature female crab         25           511
                                     sailfin molly                      32           18                 clown goby                     7             7
                                     diamond killifish                  22           8                  white mullet                   6             32
                                     immature female crab               13        132                   striped mullet                 2             77
                                     male blue crab                     10           78                 spatted seatrout               1             43
                                     darter goby                        10           5                  rainwater killifish            1             1
                                     Atlantic croaker                   8            7                  redear sunfish                 1             14
                                     sheepshead minnow                  8            4                  darter goby                    1             2
                                     gulf killifish                     7            17                 naked goby                     1             0
                                     blue crab (less than 25mm)         6            3                  ladyfish                       1             10
                                     clown goby                         4            3                                            5,096         15.010
                                     pipefish                           3            2
                                     mosquitofish                       1            0
                                     ladyfish leptocephalus             1            0
                                     ladyfish                           1            2
                                     TOTAL                        14,039        4,817

                                                                                                                                                         51
                                       Appendix Table 3. continued.

                                       Sta,tion EB (slotted-weir, back - six-foot trawl)            Station EB (slotted-weir. back - sixteen-foot trawl)

                                       SPECIES                    NUMBER    BIOMASS (g)                 SPECIES                    NUMBER     BIOMASS (g)

                                       grass shrimp               21,100        3,202                   gulf.menhaden              3.729         3,020
                                       inland silverside           1,671         939                    spot                       1,036         2,910
                                       gulf menhaden               1,226         488                    Atlantic croaker                653      2,176
                                       white shrimp                 430          198                    brown shrimp                    369      1,374
                                       spot                         291          319                    white shrimp                    336           990
                                       rainwater killifish          250          107                    grass shrimp                    321           66
                                       brown shrimp                 206          483                    inland silverside               264           220
                                       Atlantic croaker                  99      166                    pinfish                         246      1,989
                                       bay anchovy                       74           53                bay anchovy                     188           161
                                       naked goby                        70           19                male blue crab                  87       1.705
                                       pinfish                           36           61                immature female crab            85            651
                                       male blue crab                    31      311                    striped mullet                  19       1,080
                                       immature female crab              25      252                    clown goby                      4             4
                                       striped mullet                    19      137                    blue crab (less than  25 mm)    3             2
                                       darter gaby                       14           4                 southern flounder               3             285
                                       sheepshead minnow                 12           10                blackcheek tonguefish           3             33
                                       gulf killifish                    11           31                least puffer                    2             8
                                       clown goby                        11           9                 naked goby                      2             1
                                       blue crab (less than 25mm)        10           5                 spatted seatrout                1             21
                                       ladyfish                          6            1                 rainwater killifish             1             1
                                       diamond killifish                 2            1                 white mullet                    1             14
                                       white mullet                      2            31                ladyfish                        1             3
                                       sailfin molly                     2            3                 TOTAL                      7,354        16,717
                                       TOTAL                      25,598        6,833

                                       Station EM (slotted-weir, mouth    six-foot trawl)          Station EM (slotted-weir, mouth - sixteen-foot trawl)

                                       SPECIES                     NUMBER    BIOMASS (g)                SPECIES                    NUMBER   BIOMASS (g)

                                       grass shrimp                31.895        5,393                  gulf menhaden              2,922        1,969
                                       inland silverside           4,017         2,429                  spot                       1.185        3,640
                                       gulf menhaden               2,512              951               grass shrimp                    582           127
                                       white shrimp                      283          173               inland silverside               537           501
                                       striped mullet                    264          99                Atlantic croaker                508     1,565
                                       rainwater killifish               259          121               brown shrimp                    408     1,387
                                       bay anchovy                       187          157               pinfish                         372     3,223
                                       brown shrimp                      179          443               white shrimp                    292           792
                                       spot                              78           131               bay anchovy                     192           183
                                       naked goby                        78           28                immature female crab            45            681
                                       immature female crab              42           378               male blue crab                  43      1,049
                                       gulf killifish                    34           113               rainwater killifish             11            5
                                       Atlant ic croaker                 33           70                striped mullet                  10            741
                                       sheepshead minnow                 29           29                clown goby                      7             9
                                       diamond killifish                 25           12                naked goby                      7             6
                                       male blue crab                    20           169               white mullet                    3             23
                                       pinfish                           11           3                 southern flounder               2             3
                                       sailfin molly                     10           10                bay whiff                       1             1
                                       darter goby                       8            4                 sheepshead minnow               1             2
                                       blue crab (less than 25mm)        7            3                 pipefish                        1             1
                                       ladyfish                          6            2                 TOTAL                      7.129        15,910
                                       mud crab                          5            1
                                       mosquitofish                      3            1
                                       clown goby                        3            2
                                       white mullet                      1            12
                                       ladyfish leptocephalus            1            0
                                       southern flounder                 1            4
                                       TOTAL                       39,991        10,740

       -A

                                                                                                                                                        52

                                   Appendix Table 3. continued.
                                    Station CB (control, back - six-foot trawl)                       Station CB (control. back - sixteen-foot trawl)

                                   SPECIES                       NUMBER   BIOMASS (g)                 SPECIES                    NUMBER      BIOMASS

                                   grass shrimp                  9,451        1,664                   gulf menhaden               24,811       11,966
                                   gulf menhaden                 8,862        2,453                   spot                         4,264        7,190
                                   white shrimp                  1.329              512               brown shrimp                  959         1.221
                                   brown shrimp                  1,121              502               grass shrimp                  481               81
                                   spot                             806             639               bay anchovy                   374           210
                                   inland silverside                625             311               Atlantic croaker              358         1,333
                                   bay anchovy                      464             149               white shrimp                  326           292
                                   rainwater killifish              427             203               inland silverside             173           145
                                   Atlantic croaker                 40              23                pinfish                       126         1,259
                                   striped mullet                   29              51                striped mullet                 44         1,519
                                   blue crab (less than 25mm)       20              6                 male blue crab                 16           341
                                   ladyfish leptocaphalus           16              1                 mud crab                       13               8
                                   pinfish                          15              3                 immature female crab           13               12
                                   sailfin molly                    13              8                 sand seatrout                  10               64
                                   sheepshead minnow                11              12                white mullet                   10               86
                                   mud crab                           7             2                 southern flounder              10           100
                                   gulf killifish                     7             17                crevalle Jack                     8             35
                                   mosquitofish                       7             1                 naked goby                        8             7
                                   male blue crab                     6             183               rainwater killifish               6             5
                                   white mullet                       4             16                threadfin shad                    4             17
                                   darter goby                        3             2                 sheepshead minnow                 3             6
                                   naked goby                         3             0                 redear sunfish                    3             22
                                   chain pipefish                     2             9                 red drum                          2             81
                                   pipefish                           1             0                 silver perch                      2             19
                                   immature female crab               1             2                 black drum                        2         532
                                   clown goby                         1             1                 sailfin molly                     2             2
                                   TOTAL                         23,271       6,773                   blue crab (less than 25 mm)       2             1
                                                                                                      ladyfish                          2             92
                                                                                                      spotted seatrout                  I             I
                                                                                                      hardhead catfish                  1             21
                                                                                                      least puffer                      1             3
                                                                                                      diamondback terrapin              1         471
                                                                                                      diamond killifish                 I             I
                                                                                                      pipefish                          1             1
                                                                                                      darter goby                       1             1
                                                                                                      TOTAL                       32,039       27,146

                                     Station CH (control, mouth - six-foot trawl)                     Station CM (control, mouth - sixteen-foot trawl)

                                   SPECIES                       NUMBER    BIOMASS (g)                SPECIES                      NUMBER    BIOMASS (g)

                                   grass shrimp                  8,201        1,958                   gulf menhaden                12,558        7,824
                                   gulf menhaden                 4,816        1,251                   spot                          2.176        4,605
                                   inland silverside             3,538        2,238                   bay anchovy                   1,510             692
                                   bay anchovy                   3,473              880               brown shrimp                   919         1,430
                                   brown shrimp                  1,051              728               Atlantic croaker               507         1,740
                                   spot                             780             644               white shrimp                   191              316
                                   white shrimp                     750             317               inland silverside              173              165
                                   rainwater killifish              300             139               grass shrimp                   114              24
                                   Atlantic   croaker               285             214               pinfish                           63            821
                                   striped mullet                   117             92                male blue crab                    13            719
                                   ladyfish leptocephalus           52              6                 immature female crab              12            638
                                   pinfish                          45              2                 striped mullet                    11            500
                                   naked goby                       23              10                southern flounder                 8             16
                                   rough silverside                 21              48                sand.seatrout                     7             36
                                   sheepshead minnow                12              18                white mullet                      7             97
                                   blue crab (less than 25mm)       10              3                 rough silverside                  7             14
                                   immature female crab               9             15                least puffer                      4             8
                                   gulf killifish                     7             43                naked goby                        4             3
                                   pipefish                           7             7                 crevalle Jack                     3             9
                                   redear sunfish                     6             52                inshore lizard fish               3             186
                                   southern flounder                  2             3                 mud crab                          3             1
                                   leatherjacket                      1             2                 rainwater killifish               3             3
                                   pigfish                            1             1                 leatherjacket                     2             2
                                   scaled sardine                     1             1                 spotted seatrout                  1             2
                                   sailfin molly                      1             0                 hardhead catfish                  1             10
                                   male blue crab                     1             7                 threadfin shad                    1             2
                                   TOTAL                         23,510       8,679                   bay whiff                         I             I
                                                                                                      gizzard shad                      1             18
                                                                                                      r:d:ar ;unfish                    1             14
                                                                                                      d r ar oby                        1             0
                                                                                                      green goby                        I             I
                                                                                                      ladyfish leptocephalus            1             0
                                                                                                      blackcheek tonguefish             1             11
                                                                                                      TOTAL                        18.308       19,906

                                                                                                                                           53

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                                                                                        DATE SET

                                               POND              -----    SLOTTED WEIR        -          STANDARD     WEIR

                                   Appendix    Figure 1.         Number, biomass, and mean weight of                  gulf menhaden
                                                                 taken by the traps in each experimental pond.

                                                                                                 54

                          12,000                                            A

                  (Y-      8,000-
                  LLI
                  M

                  z        4,00&

                               01
                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                           7,000-
                           6,000-
                           5,000-
                   V)      4,000
                   V)
                           3,000-
                   2
                           2,000
                           1,000.
                               0

                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                             2.01
                             1.54

                             1.0
                           < 0-5@
                             0.011

                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 3',MAY 15JUN 30JUN 15JUL 30JUL

                                                               DATE

                       POND ---- CONTROL         ------- SLOTTED WEIR   -      STANDARD WEIR

                       Appendix Figure 2. Number, biomass, and mean weight of gulf
                                             menhaden taken by trawls in each pond.

                                                                                      55

                         3,000'

                         2,000
                  M

                  z       1,000.

                                                                          it
                                                           it   ol
                             01

                             15FEB 02MAR 17MAR 01APR 1 6APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                         30,000-

                         20,000-
                  (A
                  V)

                  0      10,000-
                  M

                             01-

                             15FEB 02MAR 17MAR 01 APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                            40

                            30
                           r

                           W 20'
                           3:
                           z
                           < 10
                           LU

                               01F
                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 1 5JUL 30JUL
                                                       DATE SET

                               POND      ----- SLOTTED WEIR       STANDARD WEIR
                                                    It

                     Appendix Figure 3.  Number, biomass, and mean weight of Atlantic croaker
                                         taken by the traps in each experimental pond.

                                                                                   56

                         500*

                         400,

                 LAJ
                 co      300,
                 Z)      200*
                 z

                         100,

                           0

                           15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                        1,6001

                        1,200-

                 (A
                 (A
                         800,

                         400'

                             0'

                           15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JLII In-1111

                           32'

                            24'

                            16-

                         z
                         <   8.

                             0                            T- I
                            15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                       DATE

                    POND ---- CONTROL     ------- SLOTTED WEIR      STANDARD WEIR

                    Appendix Figure 4. Number, biomass, and mean weight of Atlantic
                                       croaker taken by trawls in each pond.

                                                                                                      57

                            1,200-

                               800"

                    M

                    Z)
                               400
                                                                  fill
                                                                                   it         It

                                 0 i

                                 15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 1 SJUN 30JUN 15JUL 30JUL
                            4,000-

                            3,000-

                    V)
                            2,000-
                                                                                    it

                    M       1,000-
                                                                                   f I
                                                           it

                                 01-

                                 15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL
                                181
                                12,

                                  6,

                                0

                                '5@'EB 02MAR 17 MAP 0'AP3 16APR 01MAY 16MAY 31MAY lf,JUN 3()JtN '5kL ')!LL
                                                              DATE SE"Ir'

                                    POND         -----  SLOTTED WEIR           STANDARD WEIR
                                                                141, JIV-41

                                   1    f

                        Appendix Figure 5. Number, biomass, and       mean weight of spot taken by the
                                               traps in each experimental pond.

                                                                                                   58

                             1,600'

                     Cy-     1,200-
                     Lj
                     Co
                                800,

                     z
                                4001
                                                                                    -------------
                                   0-                                                         1@r I

                                   15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                             2,0001

                     U ol    1,500
                     V)
                     V)
                             1,000

                     Co         500'

                                   01                            1     1     i    I     I     I

                                   15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                                  15,

                                  10,

                                                            --------------------- ---

                                   01

                                   I                     16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15jUL 30JUL
                                   15FEB 02MAR 17MAR 01APR

                                                                  DATE

                        POND            CONTROL   ------- SLOTTED  WEIR  -       STANDARD WEIR

                        Appendix Figure 6. Number, biomass, and mean weight of spot
                                              taken by trawls in   each pond.

                                                                                                           39

                                   30'

                                   20,
                        M

                        z          10.

                                             ---------------------
                                     Oi , , I , - I ' ' I ' ' I

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                4,000-

                                3,000-

                       V)
                       V)
                                2,000-

                       0
                                1,000-

                                     01

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                 1500,

                                 1000,

                               z   500

                               Lj

                                     Oi

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY  15JUN 30JUN 15JUL 30JUL

                                                                     DATE SET

                                     POND         -----  SLOTTED WEIR           STANDARD WEIR

                           Appendix  Figure 7.    Number, biomass, and mean weight of southern flounder
                                                  taken by the traps in each experimental pond.

                                                                                                  60

                             10,

                              8'

                              6'
                   M

                              4*
                   z

                              2'

                              0

                              15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                            -300

                            200
                   V)
                   V)

                   0         100,

                              15FEB 02MAR 17MAR GIAPR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                             120'

                         0

                              80,

                         z    40,

                              01

                              15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                             DATE

                        POND ---- CONTROL        ------- SLOTTED WEIR          STANDARD WEIR

                        Appendix Figure 8. Number, biomass, and mean weight of southern
                                              flounder taken by trawls in each pond.

                                                                                                                61

                               1,200-

                                 800,
                     a,

                     z           400,

                                    01

                                    15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY  31MAY 15JUN 30JUN   15JUL 30JUL

                            70,000
                            60,000
                            50,000
                     V)     40,000-
                            30,000-
                     0                                                              fill
                     M      20,000-
                            10,000.
                                                                                 if
                                    0-

                                    15FES 02MAR 17MAR 01APR 16APR  01MAY  16MAY 31MAY  1 55J U N30JUN 15JUL 30JUL

                                 3 20'

                                 240-
                               r

                               UJ 160
                               3@:                    Ii,                I
                               z
                               <   80

                                    0.

                                    15FEB 02MAR 17MAR  01APR 16APR  01MAY 16MAY  31MAY 15JUN 30JUN 15JUL 30JUL

                                                                      DATE SET

                                       POND           ----- SLOTTED WEIR     -        STANDARD WEIR

                            Appendix   Figure 9.      Number, biomass, and    mean weight of striped mullet
                                                      taken by the traps in each experimental pond.

                                                                                                  62

                             3001

                             200'
                                        %

                                          %
                     z       100,         V@

                                Ot-

                                15FEB 02MAR 17MAR 01APR 1 6APR 01 MAY I 6MAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                           1,500'

                   10
                   I-
                   (A1     1,000.
                   V)
                   <

                   0         500'

                                15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL
                             120,

                           X   80,
                           0                   /.1
                           Ui

                           z   40,

                           W

                                01

                                15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                               DATE

                          POND           CONTROL  ------- SLOTTED WEIR   -      STANDARD WEIR

                         Appendix Figure 10. Number, biomass, and mean weight of striped
                                               mullet taken by trawls in each pond.

                                                                                                      63

                               6,000

                               4,000
                       M

                       z       2,000

                                     01
                                   15FES 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                               20,000'

                               15,000'

                       Ln
                       V)
                               10,000
                                                                                              t
                       0
                       M       5,000'

                                     0i     i     I     I

                                    15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                    18.
                                                                                                   UV

                                                                                                   lit
                                 :r 12,

                                 z   6

                                 Uj
                                      1    --------------------------- --
                                    C 1   @ I   - I -   I - - I , - I    I

                                    I 51FEB 02MAR 17MAP 01APR 16APR 01MA@ 16MAY 31MA@ 15JUN 30JUN 15JUL -70JLL

                                                                  DATE SET

                                    POND         -----  SLOTTED WEIR  -       STANDARD WEIR

                          Appendix  Figure 11.   Number, biomass, and mean weight of white mullet taken
                                             ----------------- ------- --

                                                 by the traps in each experimental pond.

                                15'

                                10,
                     M

                     z           5

                                15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                               160,

                               120,

                     V)
                     V)
                     <          80,

                     0
                     M          40'

                                 01

                                15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                181

                                12

                            Ld

                                 01
                               ISFEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                                               DATE

                       POND            CONTROL   ------- SLOTTED WEIR   -      STANDARD WEIR
                       Appendix Figure 12. Number, biomass, and mean weight of white
                                             mullet taken by trawls in each pond.
                                                                      - - %-4

                                                                                               65

                         30,000-

                         20,000-
                  Uj
                  M
                                                       0
                  z      10,000           t 1, 14

                               01                                              4-1     1

                              15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                         12,000*

                  V)       8,000.
                  V)

                  0        4,000-
                  M

                                                                        -44 T--r I- I
                                01    1

                              15FEB 02MAR 17MAR 01 APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                              1.2*

                           T- 0. 8'

                           W

                           ZO.4
                           <
                           W
                           M
                              0.011

                               1 5FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                           DATE SET

                                 POND        ----- SLOTTED WEIR  -      STANDARD WEIR
                         Appendix Figure 13. Number, biomass, and mean weight of grass shrimp taken
                                             by the traps in each experimental pond.

                                                                                           66

                      18,000-

                (Y-
                      12,000

                 z
                        6,000-

                            0-

                            15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                         3,000,

                         2,000-
                 (A
                 V)

                 M
                 0       1,000-

                            0 --------- -

                            15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                           0.4'

                           0-3-

                           0-2-

                       z                              ------
                         0. 1

                          0.0-
                           15FE13 02MAR 17'MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                                        DATE
                      POND          CONTROL  ------- SLOTTED WEIR       STANDARD WEIR
                      Appendix Figure 14. Number, biomass, and mean weight of grass
                                          shrimp taken by trawls in each pond.

                                                                                                           67
                           10,0001
                            8,000"0

                            6,000-
                    M
                            4,000    3
                    z
                            2,00dlo

                                 15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                             5,0001

                             4,000-
                             3,000',@@
                     V)
                             2,000
                                     1.
                     0
                             1,000

                                                                   A
                                                                 @A@_4
                                   0      A I                  . I I ' '

                                  15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY  31MAY 15JUN 30JUN 15JUL  30JUL

                                2.01

                                1.5*
                                                                                       "i-tk'
                                1.0

                             z
                             < 0.5

                                0-0,

                                  15FEB 02MAR 17MAR 01APR  16APR 01MAY 16MAY 31MAY 15JUN 30JUN '5JUL 30JUL

                                                                  DATE SET

                                     POND          -----  SLOTTED WEIR   -       STANDARD WEIR

                            Appendix Figure 15.    Number, biomass, and mean weight of inland silverside
                                                   taken by the traps in each experimental pond.

                          4,000-

                          3,000-

                   LAJ
                   M
                           2,000'

                           1,000

                                 0
                                 15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                           3,000-

                           2,000'

                    W

                    0      1,000
                    M

                                 01    1
                                 15FES 02MAR 17MAR 01APR 1 6APR 0 1 MAY 1 WAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                             1.01

                           -0.8,

                           T-
                           oO.6

                             0. 4'
                           z
                             0.2-

                             0-0,

                                 15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                              DATE

                        POND           CONTROL  ------- SLOTTED WEIR  -       STANDARD WEIR

                       Appendix Figure 16. Number, biomass, and mean weight of    inland
                                                                                           N

                                             silverside taken by trawls in each pond.

                                                                                                               69

                             1,500-

                             1,000,

                    z
                                500

                                   0

                                   15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                             6,000-

                    U
                             4,000-

                    V)

                                      Oil
                    0        2,000
                    Cn
                                   0                                        A2

                                   15FEB 02MAR 17MAR 01APR 16APR 01 MAY 16MAY 31 MAY 15JUN 30JUN 15JUL 30JUL
                                  18,
                               0oo

                                   12

                               W

                               z   6,

                                   0 i

                                   1 5FEB 02MAR 17MAR 01APR 16APR  01MAY  16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                                     DATE SET

                                      POND           -----  SLOTTED WEIR     -       STANDARD WEIR

                             Appendix Figure 17.     Number, biomass, and mean weight of gulf killifish
                                                     taken by the traps in each experimental pond.

                            30'                                                                 70

                 ce-        20
                 3
                 z          10

                                                   ---------------------
                                                          - - - - - - - - - - -
                             0i

                            15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                            90,

                            60'
                  V)
                  V)

                  0         30'
                  M

                              OT --------- I-
                              15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                             12

                              8

                           z  4,

                           Uj

                              01

                              15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                            DATE

                        POND           CONTROL  ------- SLOTTED WEIR   -      STANDARD WEIR

                       Appendix Figure 18. Number, biomass, and mean weight of gulf
                                             killifish taken by trawls in each pond.

                                                                                                           71

                            1,800

                   Of
                   W        1,200-
                   Co

                   z          600-
                                              IN
                                     ;'k                                A
                                 0                                1     1
                                 15FEB 02MAR  17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                            2,500-

                            2,000-

                   V)       1,500-
                   V)
                            1,000-
                   0
                              500'            1"ItI     A
                                                 Iit
                                 01

                                 15FEB 02MAR  17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                 4

                                 3
                                r                                                     I
                              0         1.
                              W2 -      't
                              ?-1
                              z
                              <
                              Ld

                                 01

                                 15FEB 02MAR  17MAR 01APR 16APR ClMAY 16MAY 31MAY 15JUN 30JUN 15JUL  30JUL

                                                                 DATE SET

                                     POND           ----- SLOTTED WEIR    -       STANDARD WEIR

                          Appendix Figure 19.      Number, biomass, and mean weight of sheepshead minnow
                                                   taken by the traps in each experimental pond.

                                                                                                    72

                              30'

                              20'
                                         %
                   M

                   z          10,

                               01
                               15FEB 02MAR 17MAR 01 APR 16APR 01 MAY 1 SMAY 31 MAY 15JUN 30JUN 15JUL 30JUL
                              20"

                              15'

                    V)
                    V)
                              10,

                    0
                    M          5

                               01

                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                              2.5,

                              2.0,

                              1 . 0
                           z
                           <
                           W 0.5
                           M
                              0.0

                                  15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                                DATE

                        POND            CONTROL   -------  SLOTTED WEIR          STANDARD WEIR

                        Appendix Figure 20. Number, biomass, and mean weight of sheepshead
                                               minnow taken by trawls in each pond.

                                                                                                         73

                                 300'

                                 200'

                     z           100.

                                     0

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                 400'

                                 300'

                      V)
                                 200"

                      0
                      M          100,

                                     0
                                     15FEB 021W 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL' 30JUL
                                 3.5'
                                 3.0'
                                 2.5,
                                 2.0
                              Ui
                              3: 1.5                            AA
                              z
                                 1.011               11, %1          --A   V%V'
                              LLJ
                                 0.5'
                                 0.0

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31 MAY I 5JUN 30JUN 15JUL 30JUL

                                                                  DATE SET

                                     POND        -----  SLOTTED WEIR   -       STANDARD WEIR

                           Appendix  Figure 21.  Number, biomass, a  nd mean weight of bay anchovy taken
                                                 by the traps in each experimental pond.

                                                                                                 74

                         1,600

                         1,200-

                   LLJ
                            800*

                   z
                            400

                              0 t- r       I

                              15FEB 02MAR 17MAR 01APR 1 6APR 01 MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                            400'

                            300'

                   (A
                   V)
                   <        200

                   0
                            100,

                               01

                              15FEB 02MAR 17MAR 01APR 16APR 01 MAY 1 GMAY 31 MAY 15JUN 30JUN 15JUL 30JUL

                             2.0-

                          Uj 1.0-

                          z
                          < 0.5'
                          LLJ

                             0.0-

                               15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                              DATE

                         POND           CONTROL  ------- SLOTTED WEIR   -      STANDARD WEIR

                        Appendix Figure 22. Number, biomass, and mean weight of bay
                                              anchovy taken by trawls in each pond.

                                1,600-                                                                            75

                                1,200-

                       in
                                 800,

                       z
                                 400,',

                                     0

                                     15FES 02MAR 17MAR  01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30.,UL

                                 8001

                       0         600         0

                       V)
                       <         400

                       0
                       Co        200'IA'l

                                     0

                                     15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                     2

                                 z
                                 -<        -         I
                                 LWAJ

                                     0'

                                     1 SFEG 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY    15JUN 30JUN   15JUL 30JUL

                                                                       DATE SET

                                        POND           -----  SLOTTED WEIR     -       STANDARD WEIR

                             Appendix Figure 23. Number, biomass, and mean weight of blue crab (<25mm)
                                                     taken by the traps in each experimental pond.

                                                                                                           76

                                 10,                  1rN'@

                      Li

                      z

                                   15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                   5

                       M
                       0
                       co

                                   of                              I     I     I

                                   13FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 3WUN 15JUL =UL

                                                                                          -------------
                                                                  ---------------- -
                                 z

                                   15FEB 02MAR 17MAR 01APR ISAPR 01MAY 16MAY 31MAY 15JUN 30JUM 15JUL 30JUL

                                                                    DATE

                           POND             CONTROL    ------- SLOTTED WEIR    -       STANDARD WEIR

                           Appendix Figure 24. Number, biomass, and mean weight of blue crab
                                                   (< 25  mm) taken by trawls in each pond.
                                            ,A-1/11

                                                                                                 77

                              1,800-

                                              0
                                              0
                              1,200,
                     Co

                     Z)
                     z          600

                                 01
                                 15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY -31MAY 15JUN 30JUN 15JUL -30JUL
                            18,000,

                    I-W
                    (A      12,000"
                    V)
                    0       6,0001

                                 0 --00 F                      .................7
                                 1 5FEB 02MAR 17MAR 01APR 16APR 01MAY 164AY 31MAY I-5JUN 30JUN 15JIJL 30JUL
                               140'

                                105.

                            W    70

                            z
                            <    35
                            Uj

                                                                                 A_p
                                 0

                                 15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                              DATE SET

                                 POND         ----- SLOTTED WEIR  -       STANDARD WEIR

                        Appendix Figure 25.   Number, biomass, and mean weight of immature female
                                              crab taken by the traps in each experimental pond.

                          100,

                          75'

                 M
                          50'

                 z
                          25,

                           15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN ISJUL 30JUL

                         1,000

                          800

                 (A       600

                          400@
                 0

                          200.

                            0

                            15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                            75'

                          M 50,                             'INN

                          z 25,                                   N
                          <

                                                                     %
                            01                       1  `T.    I    I   I

                            15FES 02MAR 17MAR 01APR 1-6APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                      DATE

                     POND         CONTROL ------- SLOTTED WEIR-     STANDARD WEIR

                     Appendix Figure 26. Number, biomass, and mean weight of immature
                                       female crab taken by trawls in each pond.

                                                                                                   79

                              1,600'

                              1,200-

                     Co
                                800,         It

                     z
                                400

                                   01

                                  15FES 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                            20,000,

                                                      It
                             15,000-               A

                     V)                                                it 11
                                                                 It I
                                                                        I
                     V)
                             10,000-
                                                                     I it           Wit I Iv
                     0
                                             oil
                     Co                       It
                              5,000-

                                  15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL
                                 300

                                 200
                              C

                               Z100,
                                       t'                                                It 1% to"

                                   0

                                   15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUN 30JUN 15JUL 30JUL

                                                                DATE SET
                                   POND it     ----- SLOTTED WEIR   -      STANDARD WEIR
                         Appendix Figure 27.   Number, biomass, and mean weight of male blue crab
                                               taken by the traps in each experimental pond.

                                100,

                                  80'

                      cr_
                      W           60

                      z           40'

                                  20'

                                   0i

                                  -15FEB 02MAR 17MAR 01APR 16APR 01MAY 16MAY 31MAY 15JUM =UN 15JUL 30JUL

                              1,600'

                              1,200-

                      V)
                                800'

                                400

                                   0             TV V                                         v 9
                                   13FED 02MAR 17MAR 01APR 16APR 01MAY IGMAY 31MAY 15JUN 30JUN 15JUL 3WUL
                                11 UU,

                                                                                              A
                                200'

                              W

                              z 100,
                              <                                                               -1 %
                              W                                                                   %

                                                                                                   %

                                                             ----------
                                   0                         1     1   ' I ' ' I  ' ' I ' ' I ' I 1 -1

                                   ISFEB 02MAR 17MAR 01APR 16APR olmAy 1"My 31MAy 15jUN 30jUW   15JUL 30JUL

                                                                    DATE

                           POND            CONTROL   -------  SLOrr    WEIR          STANDARD WEIR

                         Appendix Figure 28. Number, biomass, and mean weight of male blue
                                                 crab taken by trawls in each pond.

                                   20'

                                   15'

                       Me
                                   10,

                       z
                                    5

                                                      I  it

                                    0

                                    15FEB 02MAR 17MAR 01APR  16APR  01MAY 16MAY 31MAY 15JUN 30JUN  15JUL 30JUL
                              4,000-

                              3,000-

                      V)
                      <       2,000

                      0
                              1,000-

                                    ISFEB 02MAR 17MAR  01APR 16APR  01MAY ISMAY .31MAY ISJUN 30JUN 15JUL 30JUL

                                  400-

                                 3 00.
                              M

                                                               k
                                  200,
                                                                             111: IV
                                                                              it
                              < 100.                                          it
                              LLJ

                                    01

                                    ISFEB 02MAR 17MAR 01APR  16APR 01MAY  ISMAY 31MAY 15JUN  30JUN 15JUL 30JUL
                                                                     DATE SET

                                      POND         -----  SLOTTED WEIR    -        STANDARD  WEIR

                           Appendix   Figure 29.   Number, biomass, and mean weight of       mature female crab
                                                   taken by the traps in each experimental pond.

                                                                                             82

                    Appendix Figure 30. Hourly salinity for both experimental ponds taken
                         at the environmental stations by the Hydrolabs, from 17 January
                         through 30 July 1986.

                       20 -

                       15-

                       Io -

                    25DEC85 a 17           06JAN86oO7              17JAN86s2l             29JAN86ill             I OFEW6 a 00

                                                              DATE: AND TIME

                                                POND         ---------- SLorrED WEIR             STANDARD WEIR

                                    Appendix Figure 30. continued.

                                m1m                            m mow m mow= m m

                        20-

                       15 -

                        10-

                                                                            -4

                         5.

                         01

                    Z9JAN86ill                    IOFEBB6sOO                  21FEBB6sl4                    05MAR86sM

                                                           DATE: AND      TIME:'

                                              POND         --------- SLOrM WEIR              sTMMARD WEIR

                                                                                                                         f I
                                   Appendix Figure 30. continued.

                       20-

                       15-

                       10.

                        5-

                       0

                    21FFJMsl4            05MAMmO4             16MAROWIS            ZBMAR86sO8           OBAPR86sZl

                                                         DATE AN D      TIME

                                             POND        --------- SLOTM WEIR             STANDARD WEIR
                                                                                                                     Go
                                  Appendix Figure 30. continued.

                     20.

                     15.

                     10.

                      5-

                      01

                                              OSAPMoZI                     2DAPRM s I I                02KAY8601

                                                        DATE AND       TIME

                                           PONI)    - ---------  sLol"M WEIR             STANDARI) WEIR
                                                                                                                     00
                                Appendix Figure 30. continued.

                         20-

                         15-

                        10

                          5-

                          01

                     ZOAPR86sll            OZMAYB6vOl            13MkY86sl5            25MAY86s04           05JUN86slB

                                                            DATE AND TIME

                                                POND         --------- SLOllm WEIR             STANDARD WEIR

                                                                                                                          00
                                     Appendix Figure 30. continued.,

                                                                                         man

                     20-

                                                                    lit

                     10-

                      01

                   25MAY86sD4           05JUN86slO             17JUN86sO8           28JUN86o22            I OJLL86 12

                                                          DATE AND TIME

                                             POND         --------- SLOTTED WEIR            STANDARD WEIR
                                                                              0"U" oii@

                                  Appendix Figure 30. continued.

                          20-

                          15-

                          10-

                           5-

                           0-

                      28JEJN86 7-2                   IGJUL66tl2                     22JUL86:01                     OZALIG86il5

                                                                DATE AN D      T1 M E:

                                                  POND         --------- SLOTTED WEIR              STANDARD WEIR
                                                                                                                                 00
                                      Appendix Figure 30. continued.

                                                                                             90

                        Appendix Figure 31. Hourly water levels taken by the Leupold-Stevens
                               tide gauge at the environmental stations in each experimental
                               pond, from 17 January 1986 through 30 July 1985.

                                       MARSH
                                       LEVEL

                         L.Lj

                         C=
                         LJA           WEIR
                         tz-c          LEVEL

                              -15

                             16JAN86:17                               22JAN86:12                               28JAN86:07                                OIFEB86:22

                                                                                    DATE AND TIME

                                                                 POND               ---------    SLOTTED WEIR                       STANDARD WEIR

                                                Appendix Figure 31. continued.

                         MARSH
                         LEVEL

                U.1                       X
                 :@:P-
                 L.Lj
                  A

                         WEIR
                         LEVEL

                   -15

                  29JAN86:11                 IOFEB86:00                 21FEB86:14                 05MAR86:04

                                                      DATE AND      -17IME:

                                          POND        --------- SLOTTED WEIR         STAMARD WEIR

                               Appendix Figure 31. continued.

                           MARSH
                           LEVEI

                           WEIR
                           LEVEL

                     -15

                    21FEB86:14           05MAR86tO4            16MAR86:18          28MAR86:08            08APR86:21

                                                          DATE AND TIME

                                             POND        --------- SLOTTF.D WEIR          STANDARD WEIR

                                  Appendix Figure 31. continued.
                                                                         @
                                                                          IL
                                                                            lt 1,

                                                                                                                    Lj

                        MARSH
                        L-EVEL-

                        WEIR
                        LEVE

                  -10

                  -15

                 28MAR86:08                  08APR86321                 20APR86:11                 02MAY86301

                                                      DATE AND TIME

                                         POND         --------- SLOITIM WEIR         STANDARD WEIR

                              Appendix Figure 31. continued.

                            MARSH
                            L-Ev E L-

                  __j

                            WEIR
                            LEVEL

                      -10

                      -15

                     20APR86:11           02MAY86;01           13MAY86:15           25MAY86:04           05JUN86tl8

                                                          DATE AND TIME:

                                             PONI)       --------- SLOTTEI) WEIR          STMDARD WEIR

                                 Appendix Figure 31. continued.

                        MARSH
                        LEVEL

                        WEIR
                        LEVEL

                  -10

                  -15

                 25MAY86:04           05JUN86:18           17JUN86:08          28JUN86:22           IOJUL86:12

                                                      DATE: AND TIME:

                                         POND        --------- SLOTTED WEIR         STANDARD WEIR

                             Appendix Figure 31. continued.

                           10-

                                     M RSH
                                     LEV L

                      W              WEIR
                      !@  -5.        LEVEL

                         -10-

                         -15

                       28JUN86:22                     ICJUL86%12                     22JUL86:01                     02AUG86tl5

                                                                     DATE AND 71ME

                                                     POND          --------- SLOTTED WEIR               STANDARD WEIR
                                     MARSH

                                        Appendix Figure 31. continued.

                        40'

                                STANDARD WEIR
                                SLOTTED WEIR         ---------

                                GRAND. BAYOU

                        30

                     "20

                     CL

                     F-

                         10*

                          0

                          i 5FEB      02MAR        17MAR        01APR        16APR       01 MAY       16MAY        31 MAY       15JUN       30JUN        i 5JUL      30JUL

                                                                                               DATE

                                    Appendix Figure 32. Daily temperature at the levee stations in the experimental
                                                        ponds and the average daily temperature at the Grand Bayou stations.

                                                                                                                                                                                                I
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