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


                                                                                  Task 26        FINAL PRODUCT VM-RC@
                                                                                  FY 1993           Hard Clam Stock Assessment





                                          FINAL REPORT
                   FOR THE PERIOD SEPTEMBER 1, 1994 - MARCH 31,1995
                                                    SUBMITTED TO:


                    THE VIRGINIA COASTAL RESOURCES MANAGEMENT PROGRAM

                  ATTENTION: LAURA MCKAY, COASTAL PROJECTS COORDINATOR

                                 DEPARTMENT OF ENVIRONMENTAL QUALITY
                                                      P. 0. BOX 10009
                                            RICHMOND, VIRGINIA 23240

                                                      SUBMITTED BY:
                                                   JAMES A. WESSON
                              CONSERVATION AND REPLENISHMENT DIVISION
                                 VIRGINIA MARINE RESOURCES COMMISSION
                                                       P. 0. BOX 756
                                        NEWPORT NEWS, VIRGINIA 23607

                                           FOR THE PROJECT ENTITLED:
                   [FISHERY INDEPENDENT STOCK ASSESSMENT OF VIRGINIA'S
                           HARD CLAM POPULATION OF THE CHESAPEAKE BAY
                                 o PTMOsp@,
                                                           DATE REPORT SUBMITTED JUNE 7, 1995



                                                                This Clam Stock Assessment Project was funded,
                        0
                                   nom                            in part, by the Department of Environmental
                                                                Quality's Coastal Resources Management Program
                                                                 through Grant #NA370ZO360-01 of the National
                      0                                  >
                                                         -4    Oceanic and Atmospheric Administration, Office of
                                                         0      Ocean and Coastal Resource Management, under
                       7Z                                          the Coastal Zone Management Act of 1972,
                                                                  as amended. The views expressed herein are
                                                                 those of the authors and do not necessarily
                                                                      reflect the views of NOAA or any of
                                                                                Its subaqencles."
                                                00
                                 @A4ENT Of











              ABSTRACT




                     The hard clam (Mercen  aria mercenaria) is one of the most importnt commercial species

              harvested in Virginia!s Bay waters. As the oyster and other commercially harvested species have

              declined, a portion of the displaced workforce has joined the clamming fleet. Declining catches

              have raised concern for both watermen and fishery managers; however, little current information

              was available for either hard clam standing stock levels or age structure. The current project used

              a fishery independent stock assessment method using a hydraulic patent tong sampling device to

              survey hard clams in the James River-Hampton Roads area. When compared with results from

              previous stock assessment estimates in this area, the current clam densities and standing stocks

              were not obviously different. Age and size structure has changed since earlier studies, with less

              larger and older clams in the current population. Declines in the commercial clarnmer's catch per

              day may be explained by a decrease in the number of high density clam areas over the many years

              of fishing. Today's clam populations may be more uniformly distributed, resulting in the

              individual clarnmer catching less clams per day because in each patent tong grab there are less

              clams and the physical limit on the number of tong grabs that can be handled on any one day.




              A(XNOWLEDGEMENTS

               We thank John Register and Calvin Wilson for boat operation and patent tong sampling; Gerry
               Showalter, William Kuster, and Benny Stagg for map preparation; David Bower for sampling
               assistance; and Kathy Leonard for report preparation, all from Virginia Marine Resources
               Commission. We also thank numerous Virginia Institute of Marine Science students, Linda
               Crewe, Tommy Leggett, and Lee Ferguson for their assistance with field sampling, under often
               unpleasant weather conditions.













              WrRODUCTION




                     The hard clam     ercenaria mercenaria) is one of the most important commercial species

              harvested in Virginia!s Bay waters. Annually since 1987, dockside values have varied from four

              to six million dollars, with over a n-dilion pounds of meats landed each year. As the oyster and

              commercial finfish resources have declined, the clam industry has absorbed some of that displaced

              fishing effort (Figure 1, Table 1). There has been a doubling of the clamming workforce during

              the: past 10 years and this added harvesting pressure on the clam resource has caused concern for

              fishery managers at the Virginia Marine Resources Commission (VMRC). Catch figures indicate

              an initial increase in harvest levels following the increase in the workforce; however, since 1990

              there has been a decline in harvest and a decrease in the total catch per licensee. Anecdotal

              information from watermen has also suggested that the fishermen are working longer hours with

              more sophisticated equipment to catch the same or declining quantities of clams.



                     A clam management committee at VMRC is currently meeting regularly to discuss and

              evaluate the regulatory changes necessary to protect the fishery participants and to stabilize the

              claim resource. Options being considered include limited entry, minimum and maximum size limits

              on clams, daily time and catch limits, and sanctuary areas. They have been unable to offer

              significant suggestions for further regulation due partly to the lack of real data on clam stocks. It

              is extremely difficult to propose and defend new regulatory efforts based only on catch figures

              without having current information on standing stocks and age structure of hard clam populations.


                                                                                                              2









                       This project was proposed to begin quantitatively assessing the current status of hard clam

               resources in Virginia. We have been using a random sampling methodology, employing a

               hydraulic patent tong to give a fishery independent stock assessment of oysters and we have

               adapted this procedure to collect similar data for hard clams. Rather than proposing an

               exhaustive survey to sample from all areas within the Bay, we have initially sought to provide

               adequate comparative and baseline data for areas where management decisions are urgently

               needed. Specifically, this project had three goals:



                       i)     Assess the relevant clam survey literature from past projects in the Chesapeake

                              Bay and determine where direct comparisons could be made with current data on

                              clam population numbers.



                       ii)    Map, produce sampling grids with randomly selected samples, and sample the

                              current clam populations on the areas that were identified in the literature search as

                              well as those identified by VMRC as important harvesting areas.



                       iii)   Estimate the current stock densities, age, and size distributions of clam populations

                              for comparison to previous projects, and establish a baseline for evaluating the

                              effects of current or future management decisions.








                                                                                                                    3











              WITHODS




                     A search of reports on Virginia!s clam resources uncovered several hundred locations that

              had previously been sampled for clam densities (Haven, et al, 1973, Haven and Kendall, 1974;

              Haven and Kendall, 1975; Haven, et al, 198 1; and Kvaternik, 1982). The stock assessment

              methods varied in these reports, but all could be converted to an estimate for clams per acre or

              total standing stock. Additionally, some of the reports had information on the size distribution of

              clams at that time. Using these reports, our efforts began in the lower James River-Hampton

              Roads area where past data was most complete and an important clam fishery exists today. The

              entire Hampton Roads and lower James River area was mapped, and gridded with Loran

              coordinates by the Surveying-Engineering Division of VMRC. Sample locations were randomly

              selected and marked on a map at a rate of one sample for each 10 acres of submerged bottom.

              Approximately 25,000 acres were plotted and 2500 samples selected for the area between the

              Hampton Roads (1-64) Bridge Tunnel and the James River Bridge (Route 17), including most of

              the Elizabeth and Lafayette Rivers. All potential clam producing areas were included, except for

              areas that were leased by private individuals. Swnples were collected with a hydraulically

              operated patent tong operated from the 42 foot fiberglass workboat, I B. Baylor. This type of

              patent tong separates the closing action of the tong from the retrieval action. In our studies, this

              has proven to be the most accurate method for consistent bottom penetration for sampling. The

              open dimensions of the tong were such that it sampled I square meter.



                     On each sampling day, a crew of 6 or 7 people conducted the sampling operation. The


                                                                                                            4









             boat operator located the sampling location with a Northstar Loran which has been corrected to a

             known location on each sampling day. At the sampling location, the tong operator lowered the

             open tong to the bottom, closed the tong, and raised the sampling grab on to a sorting table on

             the boat with the assistance of a second individual. The entire sample grab, including mud, shells,

             and clams was processed by hand and running water by the other 3 individuals on the boat.

             Water depth, bottom consistency, and the length, width, and height of all five clams and clam

             boxes (emply clam shells with the hinge attached) was recorded. We had originally planned this

             prcject for the summer months. Funding was only available in the winter and the sampling

             process was somewhat more difficult than anticipated. We had estimated that we could sample

             anti process up to 200 patent tong samples per day. The work on the boat was more difficult in

             the cold and windy conditions of winter and with the cold water, the bottom sediments were

             harder to sort than originally envisioned resulting in only 100 samples being processed per day. In

             the 20-day sampling period, approximately 2000 samples were processed and more than 20,000

             acres were surveyed. When it became apparent that we could only process 100 samples per day,

             we concentrated on the most important areas of the Lower James and Hampton Roads and did

             not attempt to go further in the Bay.



                     Clam numbers and sizes, as well as the bottom type and depths were archived in a custom

             database program at VMRC. Clam densities were determined for the entire area and a map of

             densities was generated. A subsample of clams in each density area was analyzed for the size

             distributions.






                                                                                                            5







               3





             RESULTS AND DISCUSSION




                     Mean densities of clams are presented in Figure 2. The highest densities of clams were in

             the center, deeper areas of the lower James River between Newport News Point and the Hampton

             Roads Bridge Tunnel. Areas were separated for presentation using a combination of depth,

             density, bottom sediments and similar divisions in previous studies. A general description of

             each individual area follows:




                     A.     Northern nearshore area between Newport News Point and Hampton Roads

                            Bridge Tunnel, mostly shallow (<8 feet) with sandy bottom and a moderate density

                            of clams (area approximately 2,180 acres; 7,001 clams/acre).

                     B.     Mddle area on the north shore between Newport News Point and Hampton Roads

                            Bridge Tunnel at intermediate depths (8 - 18 feet) with sandy or sandy-mud

                            bottom, and moderately high density of clams (2,770 acres; 10,450 clams/acre).

                     C.     North channel edge and channel between Newport News Point and Hampton

                            Roads Bridge Tunnel, sandy or sandy-mud bottom, > 18 feet deep, with the second

                            highest density of clams (1,950 acres; 13,193 clams/acre).

                     D.     South side of the channel and part of middle ground area, >18 feet deep, generally

                            sand or sandy-mud, with the highest density of clams (1,040 acres; 15,055

                            clams/acre).

                     E.     Mddle ground area, soft mud to sand, 16 - 25 feet deep, moderately high clam

                            density (1,520 acres; 6,100 clams/acre).


                                                                                                           6









                     F.     Craney Island area - north, east and west of Craney Island with hard sand to soft

                            mud of varying depths. No clams were caught in any of more than 150 sample

                            locations (4,000 acres).

                     G.     Elizabeth River - varying bottom types with low density of clams (3,415 acres; 298

                            clarns/acre).

                     H.     Lafayette River - mostly sand or sandy-mud bottom with a moderate density of

                            clams (580 acres; 5,058 clams/acre).

                     1.     Nearshore area on north side of James River between 1-664 and the James River


                            Bridge, mud, mud-sand, and sandy bottom mostly in the channel area adjacent to

                            Newport News Shipyard, moderate clam density (2,150 acres; 6,799 clams/acre).

                     J.     South side of Newport News Channel from 1-664 to the James River Bridge, mud

                            to sandy-mud, 10-30 feet deep, low clam density (1,375 acres; 1,781 clams/acre).

                     K.     Middle of James River between 1-664 and Cruisers oyster bar, moderate depth,

                            with muddy bottom and low density of clams (1,225 acres; 93 clams/acre).

                     L.     Cruiser's Oyster Bar, old oyster bar with significant shell deposits and low clam

                            density (425 acres; 1,721 clams/acre).

                     M.     Middle of the James River above Cruiser's Rock, moderate depth with mud

                            bottom, zero clams were found in more than 100 samples. (1,400 acres)

                     N.     Nfiddle of the James River next to the James River Bridge, moderate depths with

                            some oyster shell and mud or sandy-mud bottom with low clam density (1,500

                            acres; 171 clams/acre).




                                                                                                            7









                      Areas A, B, C, D, E, and I are the main areas for the summer relay clam season in the

              James River, where in many years more than 50% of the annual harvest of clams in the entire

              state has originated. This area is closed to harvest except during the summer because of high

              bacterial levels. Fishing is permitted during the summer in a relay program, whereby, polluted

              claims are harvested and moved under state supervision to other clean water areas where the clams

              must remain for 15 days prior to direct marketing. The focus for much of the discussion on clam

              management has centered on this important area. Accurate figures for harvests for the past 14

              years are included in Figure 3. Harvest figures increased from 1986 - 1988, which is mostly

              attributable to the increase in the patent tong clam fleet presented in Figure I and Table 1.

              Harvests have declined since 1988 and the commercial clarnmers have indicated that their


              catch/boat has also declined. Prior to the study, we would have predicted a substantial decrease

              in the standing stock of clams in these areas from those reported in previous studies. Published

              results from Haven, et a] (1973) and Haven and Kendall (1975) in Figures 4 and 5 show mostly

              similar distributions and densities of clams to the current project, although there appear to be

              more high density areas in the earlier studies than in thepresent study. Methodologies were quite

              different between studies, with less sites and more replication within sites in the previous studies

              than the current project. In a later report, Haven, et al (1981) combined data from all their

              previous reports and produced an estimate of the clam standing stocks in the entire area. This

              estimate was 565,712 bushels or 141,428,000 clams in the James River-Hampton Roads area.

              Kvaternik (1982) also estimated the standing stock of clams for this area using the harvest figures

              and catch per unit effort information with the Leslie method. This method could be quite

              accurate in this area because of the excellent harvest figures that have been maintained each year


                                                                                                                 8







                A



              with the relay program. For the period from 1978 through 198 1, standing stocks varied from

              70,290,535 clams to 139,815,328 clams with an average of 99,582,920 clams for the four-year

              period. If calculations are made with data in the current project, the standing stock would be

              estimated at approximately 112,000,000 clams. All of these estimates of standing stocks are

              reasonably similar and do not obviously indicate any major decline in clam populations associated

              with harvesting activity. Anecdotal information from the commercial fishermen suggests very

              strongly that their catch per day has indeed declined, especially during the last 5 to 6 years. At

              first inspection, these results seem to be contradictory; however, inspection of the sampling results

              in Figures 4 and 5 shows some very densely populated clam areas within the overall area. The

              patchy nature of high density areas of clams in the past may explain the higher catch rates in

              previous years. The efficiency of the clam harvester has improved with the use of better depth

              sounding equipment along with the Loran equipment that allows the watermen to both locate and

              return to these "patch" high density areas. It is very likely that with the increase in harvester

              numbers and the increase in efficiency, that the high density spots have mostly been caught and

              what now remains are relatively uniform concentrations of clams. The density per acre and

              standing stock for this entire area has remained constant; however, the success of the harvester

              has declined, because there are less "hot spots" or high density areas and the catch in each patent

              tong grab has declined and the clarnmer can only make a certain number of grabs in any one day.

              The clam populations appear to be healthy and able to maintain a relatively stable population with

              the observed 15% to 20% annual harvest rate (approximately 15,000,000 - 20,000,000 of a total

              of 1.00,000,000 clams).




                                                                                                                   9









                     One change in the harvested clam population that does appear to be occurring is in age

              structure. Table 2 presents results of the mean size and size frequency of a subsample of clams

              from several of the sampled areas in the current project. In Table 3, a comparison between 1974

              and 1995 data for mean size and size frequency is presented. It would appear that the average

              size of clams has declined during the past 20 years. Additionally, there are fewer clams in the

              chowder or larger clam category in the current project. Both of these observations may be cause

              for concern and should be monitored in later studies. It would appear that very few clams escape

              harvest and reach the larger size category. Clams are long lived and grow slowly, and may take

              12 to 20 years to reach chowder size (Haven, et al, 1975); and therefore, even though the harvest

              of chowder clams is limited, clams are subject to harvest at smaller sizes for many years. Very

              small quantities of clam boxes were observed in any of the sample areas which would indicate

              very little natural mortality besides harvesting. If larger animals are better spawners, over time

              there may be a reduction in spawning success in future years.



                     Much of the Elizabeth and Lafayette Rivers were sampled in the current project because

              there has been some interest in opening this area to harvest and the relay process. Currently these

              rivers are closed entirely to the harvest of shellfish because of pollution. Stock assessment results

              provide little evidence of significant clam stocks in the Elizabeth River (Figure 2). A moderate

              density of clams was present in the Lafayette River; however, the total acreage was small and

              would not support a very large fishery. The excellent reputation of Virginia!s clam products could

              be jeopardized by the opening of this insignificant clamming area.




                                                                                                              10











              CONCLUSION




                     In conclusion, results in this project indicate that the standing stock of clams in the lower

              James River-Hampton Roads area appears similar to previously reported levels from studies as

              long as 25 years ago. A decrease in the success of the clammers as reflected by a decline in the

              overall harvest and the catch per unit effort may be explained by a change in the distribution of

              claims on the bottom. Years of harvest may have reduced the "patches" of high density clam

              areas and resulted in mostly uniform distribution of clams. This seems to indicate that a relatively

              stable clam population level may be maintained at the same time that the health of an industry is

              declining.



                     Secondly, there appear to be changes in size and age structure during this 20-year period

              resulting in less larger, older clams in the current clam population. These changes have not

              resulted in a decline in clam populations, but this area should be resurveyed at a later date.

              Additionally, further sampling of other clam areas should be completed for comparison. If gear

              and season regulations remain the same, it is unlikely that catch per unit effort will increase

              substantially over those observed currently. If harvesting pressure is decreased by limiting the

              panicipants in the fishery, it would appear likely that densities of clams could increase and allow

              the catch per day to improve.



                     Results of this study will be presented to the VMRC Clam Management Committee and to

              the full Marine Resources Commission.











                                               LUERATURE CMD




            Haven, D. S., J. G. Loesch, and J. P. Whitecomb. 1973. An investigation into commercial
                    aspects of the hard clam fishery and development of commercial gear for the harvest of
                    molluscs. Contract No. 3-124R. Virginia Institute of Marine Science, Gloucester Pt., VA.
                    58 p.

            Haven, D. and P. Kendall. 1974. A final report to Virginia Department of Highways on hard
                    clam, Mercenaria mercenanj populations in the vicinity of Hampton Roads Bridge Tunnel
                    (1-64). Virginia Institute of Marine Science, Gloucester Point, VA. 36 p.

            Haven, D. and P. Kendall. 1975. Studies for a proposed Nansemond River Sewage Treatment
                    Plant. Volume 4. A survey of commercial shellfish in the vicinity of Newport News Point
                    and Pig Point in the lower James River. Virginia Institute of Marine Science, Gloucester
                    Pt., VA. 30 p.

            Haven, D. S., R. Morales - Alamo, and W. I. Priest. 198 1. Oyster and hard clam distribution and
                    abundance in Hampton Roads and the lower James River. pp 38-43. In A Study of
                    Dredging Effects in Hampton Roads, Virginia. W. L Priest, ed. Special Report in Applied
                    Marine Science and Ocean Engineering No. 247, Virginia Institute of Marine Science,
                    Gloucester Point, VA. 266 p.

            Kvaternik, A. C. 1982. Analysis of population and price aspects of the Virginia hard clam
                    (Mercenaria mercenaria) fishery. M. A. Thesis. College of William and Mary,
                    Williamsburg, VA. 103 p.














                                                                                                 12







                                                       FIGURE 1. HARD CLAM LANDINGS (POUNDS)
                                                             NUMBER OF PATENT TONG LICENSES



                                       1.8-                                                                                                         400
                                                                                                                  i .......... ............. .... .... ..... ..............L
                                  p    1.6   . ..... ..... ... .. .......... . .... .. . ... . . ..... ........ ... ........... ............ ... ... . ..... ................... ..... . . . .... ..... ....... ---i
                                  0                                       . . ................... . ... . .@\ ................ . ... .. . .........I. . ....... ................ . ...... . .-.. . . . . . .. ...................... . .. .................. .. . ................ .c
                                  u    1.4   . . . .... . ........... . .. . ........ . ....... . . . ... ....... . ............... ...................... 300  e
                                  n                                                                                                                             n
                                       1.2         . .. . .............. . . ..... ............. . ...... . ... ...... ..... . ........
                                  d                                                                       -, li;@ ,                                             s
                                                                                                            19W  619,712
                                  s          . .. . ...... .....  ... . ..       ..... . ........ . .       1541 1.11                                           e
                                           1      A    - - - ----- ---------------                        -Im                                                   s
                                  M                                                                       -Im                                       200
                                  i    0.8   . .. . ..... .                                                 39"- Ing.191 - - ------ . . . . ............ . ....... . ..H
                                                                                                            INS  461=4
                                                                                                            M    M177                                           u
                                  1    0.6                                                                -1"7                                                  n
                                                                                                                                                                d
                                                                                                                                                    100
                                  o    0.4   . . .... ........ . . ..... .......................... . .. . ... . ..... ...... . ...... . ..... ..... . . . . ...... . ..... . ................ ..... ... . . .... . ......r
                                  n                                                                         101  L-0-06                                         e
                                  s    0.2   . .. ...... .............. ................... . ........... . ..... ... .......... ... . ............ . .......... . . . ............. . ................. . ..... ......... ........... ...... . ..... ........ . ............... .. . ................ .... . ........ . ...... ...........d
                                                                                                          --rim
                                                                                                                                                                s
                                         0-                                                                                                         0
                                             80 81 82 83 84 85 86 87                                     88 89 90               91 92 93
                                                                                           Years


                                                                     - Clams                           Licenses


                         *Preliminary data









                                                                                                            REV 5/30/95
                                          TABLE 1. HARD CLAMS LANDINGS (POUNDS)
                                                   NUMBER OF PATENT TONG LICENSES
                                                ..............                                                      ... .....
                                                  .....    ..........                                               ......
                                                .............
                                          .......... ............ .
                                          .......... .............                                     pou..
                                                                                                      ...........
                                          .......... :::: . . ..... .                                   ........ ..  ........
                                                                                                               ...... ...
                                               .......... .. . ........
                                                       .......... ... ...............          ...                      ....
                                                                                                                  'SE.
                                          ...                    ND*,*:*:"***#'
                                                                                          ES:
                                                1980          619,712                     133                    4,659

                                                1981        1,110,530                     174                    61382

                                                1982          711,170                     186                    3,823

                                                1983        1,207,165                     188                    6,421

                                                1984          739,191                     163                    4,535

                                                1985          613,254                     332                    1,847

                                                1986          905,177                     230                    3,936

                                                1987        1,004,580                     266                    3,777

                                                1988        1,307,863                     335                    3,904

                                                1989        1,517,488                     366--                  4,146,

                                                1990        1,559,108                     382                    4,081

                                                1991        1,068,243                     367                    2,911

                                                1992        1,094,391                     375                    2,918

                                               *1993        1,313fi59                     357                    3,680
                                                       1 --
                                             Preliminary data







                                                                                                                     FIGURE 2
                                                                                                 B/



                                                                 A

                                                                                                     17
                                                                 Y17 1.
                                                                                             c
                                                     NEWPORT
                                F1 7- @l                                                          --4
                                                     NEWS
                                                     POINT
                                                                                                      L6




                                         Fo-1







                                                                            Ell



                                                                        CRANEY                  H

                                                                         ISLAND

                                                                                                         'AA V,

                                                                                        02-9-61














                           DENSITY



                                   NZ 501-5000
                                     I0-sw
                                                                  17MI'
                                                           RT

                                                                            1, @E
                                                                              y

                                                                             ND
































                                      5001-10000
                                                              71@
                                      10001-15000


                                      15001-20000







                            FIGURE 3. CLAMS RELAYED
                               FROM POLLUTED SHELLFISH AREAS, 1980-1994



                           35




                           30   . .............. ... . . ... ... . ............ .. . . . ... . . . ....... .... .. . . ........ . ........................... ... ........................




                           25-------      .. .. .. ........... .. ...... . . . ...... .......... ..... ............. ...... .. ... ....... ........... .


                     M
                           20                                . ........... .. .. . .. ... .... . .... ....................................................................... .........................



                     0     15   . . . . . . ... .................... .. . .....................................  ............ .............. .............. .............. ............. .... ......... ... ..........
                     n
                     s


                           10-                      . . ...... . ....  ............  .. . . . ......... .. ... ..




                            5-                 .. .. ............ .....  ...........-. .............. .. .............. ............. .......... .. .........




                            0-
                                80 81 82 83 84 85 86 87 88 89 90 91 92 93 94



                                                                     COUNT



                5/23/95










                                                                        @Mn-kT r%V Q@r A 'rTr% 11 SAMPLIr                I                                T@nt_%lk 4'
                                                                                                                    'Dyy JLIT
                                             FIGURE 4.        T   OCA                 L3 X Ilk 110 No                           r A 'IM-4 I   I O.NGS FROXIL
                                                                                                                           I KIL
                                             CHARTERED VESSEL. ABUNDANCE CODE: HlGH (716,500 CLAMS/ACRE), CLOSED
                                             TRIANGLE; NdEDIUM (6,900 - 16,500 CLAMS/ACRE), HALF-CLOSED TRIANGLES; LOW
                                             (<6,900 CLAMS/ACRE), OPEN TRIANGLES. (ORIGINAL DATAFROM HAVEN, ET AL.,
                                             1973)

                                                        7.60IP8"                                   76012-44'                              760120
                                                                                                                                                       b's
                                                                                                                                                 .6@b
                                     306&-             &302
                                          30410'
                                             6298 30              vo     84
                                                                         28 5.                                                                                          217            370
                             370             299                                                                                    .......
                                                                8
                                                                                                                                                                  276       278.....-
                                                              289                                                                                                                      00
                             5-0-r                                                                                           ........
                                                                                                                                                       267
                                             IN,               %3A
                                                                          ï¿½44    4-*@'.-'-                                                        266          275A@
                                                                295                                                                            265
                                                                          3
                                        ..300                     297 .11
                                                                                                                                             264
                                                                                 U.
                                                    V)
                                                                                                                                          263
                                                          .311      2                                     A-952                         262
                                                                                      NEWPORT.-.
                                                                                                                                                                    """'273 274
                                                     %      309,@k      319           N.E WS              251@      2@6p                                                      ALV - -
                                                                                                                                                                                  272
                                                         ......           308                               J58,42V9
                                                                307
                                                                     A
                                                                                                53                                                              willou
                                                                                                                223
                                                                                                                                                                        vO
                                                                                                            :@2
                                                                                             220.              2
                                                                                            244        &245 &J4
                                                                                                       239A
                                                                                                240A
                                                                                                       AH8 @jL235
                                                                                                237
                                                                                                23 eA 230 V43
                                      ..t-       Xf                                          231            POL232
                                     .:" ':fm.
                                                                                                                                                       ;"-.:-'.NORFO
                             360                                                                :.4229  22e@&  A227                                                                 :'360
                                                                                                         A226
                                                                                                225A
                                                                                                                              Hampton
                             56.                                                                       A2                                                                              56
                                                                                                                       Ro    ds
                                                                                313             19 2i.@
                                                                                                A      216
                                                                                           214     215&
                                                                        315
                                                                                                   09
                                                                                                          11 fe.,
                                                                                                        0
                                                                                                       WA2026%4
                                                                                                2of                           D
                                                                                                203
                                                                                                   A201
                                                        760 28'.                                   760 24'f-                              76012d
                                                                         v
                                                 )83
                                             2 9 9
                                                                   3 4AA@,
                                                                      A









                                                            FIGURE 5


             DENSITY OF CLMff-.S PER ACRE IN THE
             HAMPTON ROADS AREA FROM A REPORT
             EY HAVEN AND KENDALL, 1975




                                                                                  CLAMS
                CRUISER SHOAL                                            AREA PER ACRE
                ROCK
                                          WARWICK                        1.             90
                                           HOTEL                         2.       18,90Q
                                                                         3.       17,460
                      -7                                                 4.        1,800
                PUBLI                                                    5.       23,400
                GROUND                         NEWPORT.
                                                  NEWS                   6.        9,600
    FISHING                                        PT                    7.           330
    PT
                                                                         8.        3,630
                                     08                                  9.        1,650
                                                                         10.             0



                                                                        iuoLE'
                                                                       GROUND



       CANDY
       Pl




        PRIVATE
        LEASES
                       Ie 1Q,
        NANSEMOND      1,
          RIOGE


                                                                      CRANEY
                                                                      ISLAND

    BARREL


         P R I VAT E.
           EAS


                                 PIG
                                 POINT                      \+   360 5- N-
                                                                  W


  CEDA                                         STREETER
   PT                  PRIVATE                 CR.      HOFFLER
                       LEASES                           CR.


                             WEST
                             CR.      0.   1000   2000  3000
                                              YARDS


                       KNOTTS                BOUNDARY OF SAMPLE AREAS
                         CR.                 DiVISON BETWEEN FORMER AND LATTER
                                             SAMPLING
                                             BOUNDARY OF PUBLIC OYSTER GROUNDS
     T












                                                                     TABLE 2. MEAN LENGTH AND SIZE FREQUENCY OF HARD CLAMS
                                                                                                  IN THE HAMPTON ROADS AREA
                                                                                      .......... .............            .. ....                ...                                    ...
                                                                                                                        .............  ..........
                                                                        .............. .
                                                                                                                                                          ..............
                                                                             .......                                                                                          TR QU...
                                                                                                                                                                                   E
                                                                                                                             ..........  -TH
                                                                                                               . .......... .. .. ........                                                                . . ........
                                                                             .......            ..........                                                                               .. .....       ... ...
                                                                                                                                                 . ......... .............. ............ ......... ....        ................
                                                                                                      . ................
                                                                                                                                                                                            R. RY:'***
                                                                                                                                                                              :::K       E                          Ef.
                                             ..........                                                                                          ...........
                                       ....................
                                                                                                              ....        .......                               ..... ...                                 .... . .
                                                                        ..........                                      ....          .. .....
                                           .......          ... .                            . .......
                                                                                                                                                                                                            -:81
                                       ...... ...                                                                  "'MEAN                                          60hibi
                                                                                                                                                 SD                                             .........
                                                                                                                                      4 @        ......... -. ....
                                                        .. ....... ..... . .............. . .. ...........                                       .........
                                                                                                 ..........                                             . ........


                                       A     HAMPTON, INSHORE                                              77                         70.7       14.4                         17                  56                27


                                       B     HAMPTON FLATS                                                 60                         67.2       16.4                         25                  50                25


                                       C     HAMPTON > 18 feet depth                                       161                        63.5       16.9                         37                  48                15


                                       D     MIDDLE GROUND                                                 143                        73.4       10.3                         10                  65                25


                                       1     NEWPORTNEWSCHANNEL                                            91                         52.7       14.3                         68                  30                   2


                                       H     LAFAYETTERIVER                                                45                         63.7          9.4                       36                  64                   0


                                       5/30/95












                                          TABLE 3. A COMPARISON OF MEAN LENGTH AND SIZE FREQUENCY OF HARD CLAMS
                                                            FROM 1974 (HAVEN, LOESCH, WHITCOMB, 1974) AND 1995

                                                                                                            Iyjij@i@                              ..... .......
                                                      ............
                                                                              ............
                                          .................  ...............
                                          ............ .. ........ . .........
                                                   ............  ......                  . ......
                                                .......I...........
                                                  ... ..............
                                                                                                  ..........0                                 .........
                                                                            ......................                                  ......    ..........              .........
                                                                                                                           N      K:::::CHER
                                                                             ........................
                                                                                           FAN
                                          YEA                                ....................
                                                                              ..... ......
                                                                   RE.A:::::  .............     ..             :.LIT...TLE::   EC

                                           1995         Hampton, inshore                               70.7                       17                56                27

                                           1974             Hampton Bar                                79.5                       10                36                54

                                           1995           Hampton Flats                                67.2                       25                50                25

                                           1974           Hampton Flats                                75.2                       12                47                41

                                           1995        Hampton > 18 feet                               63.5                       37                48                15

                                           1974        Hampton > 18 feet                               69.4                       23                51                25

                                          5/31/95




  /I
                                                                                                                                                      I     NOAA COASTAL SERVICES CTR LIBRARY                   .
                                                                                                                                                      .    @ @11111 1@1@1 11@11 11@1@ 1111, @1111 @1111              1 - I v r
                                                                                                                                                             3 6668 14111981 0 '