ML072680380
| ML072680380 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/15/2003 |
| From: | Celestino M State of NJ, Dept of Environmental Protection |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| 2130-07-20506, TAC MC7624 | |
| Download: ML072680380 (48) | |
Text
New Jersey Department of Environmental Protection I
SHELLFISH STOCK ASSESSMENT OF LITTLE EGG HARBOR BAY (DSRT PROPOSAL #2001011)
Project Manager: Mary Downes Gastrich, Ph.D.
Division of Science, Research and Technology Principal Investigator: Michael P. Celestino Bureau of Shellfisheries Prepared by: Michael P. Celestino Bureau of Sheilfisheries Date Submitted: 15 May 2003
TABLE OF CONTENTS LIST OF TABLES iiS, LIST OF FIGURES iv ABSTRACT 1 INTRODUCTION 1 MATERIALS AND METHODS 2 Study Site 2 Sampling 2 Population Size/Age Structure 4 Mercenaria Distribution and Abundance Estimation 4 MercenariaMortality 5 MercenariaRecruitment 5 Statistical Analyses: Mercenarif abundance 6 Statistical Analysis: Mercenariamortality 7 Statistical Analysis: Mercenariarecruitment 7 Statistical Analysis: Mercenariasize/age 7 Submerged Aquatic Vegetation (SAV) Distribution 7 Statistical Analysis: Submerged Aquatic Vegetation 8 RESULTS 8 Description of Study Site 8 Submerged Aquatic Vegetation 8 MercenariaAbundance and Distribution 9 Population Structure 10 i
Recruitment 1.0 Mortality 10 Associated Conmmercial Species' Abundance and Distribution 11 DISCUSSION AND CONCLUSIONS 11 ACKNOWLEDGEMENTS 13 LITERATURE CITED 13 Hi
LIST OF TABLES Table. Page
- 1. Estimates of dredge efficiency among five substrates examined. 5
- 2. Physical and chemical data collected during the 2001 Little Egg Harbor Bay hard clam stock assessment. 15
- 3. Comparison of acres of submerged aquatic vegetation (SAV) mapped in Little Egg Harbor Bay from the 1986/87 and 2001 surveys. 8
- 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence of submerged aquatic vegetation (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay. 16
- 5. Comparison of hard clam stock estimates in Little Egg Harbor Bay from the 1986/87 and 2001 hard clam surveys. 9
- 6. 2001 Little Egg Harbor Bay hard clam stock estimates, means, standard deviations and standard errors by commercial size class. 22
- 7. Comparison of the number and percent of stations sampled in 1986/87 and 2001 with no hard clams, low, moderate and high abundances of hard clams. 23
- 8. Comparison of hard clam abundance statistics from Little Egg Harbor Bay between the 1986/87 and 2001 surveys. 10
- 9. Comparison of hard clam population statistics (number collected, mean size, and standard deviation of sizes) in Little Egg Harbor Bay for the 1986/87 and 2001 surveys. 10
- 10. Comparison of 1986/87 and 2001 recruitment and mortality indices for Little Egg Harbor Bay. 24
- 11. Comparison of mortality intervals between the 1986/87 and 2001 surveys. 11
- 12. Average, minimum and maximum abundances of species collected during the 2001 hard clam inventory of Little Egg Harbor Bay. 25 iii
LIST OF FIGURES Figure Page
- 1. Location of the 2001 shellfish inventory sampling area (Little Egg Harbor Bay, Ocean County, New Jersey). 26
- 2. Schematic of systematic sampling design grid. 3
- 3. Conceptualization of null hypothesis for submerged aquatic vegetation (SAV) analysis. 8
- 4. 1986/87 Little Egg Harbor Bay Shellfish Inventory: SAV distribution. 27
- 5. 2001 Little Egg Harbor Bay Shellfish Inventory: SAV distribution. 28
- 6. 2001 Little Egg Harbor Bay Shellfish Inventory: station locations. 29
- 7. 1986/87 Little Egg Harbor Bay Shellfish Inventory: distribution and abundance of the hard clam, Mercenaria mercenaria. 30
- 8. 2001 Little Egg Harbor Bay Shellfish Inventory: distribution and abundance of the hard clam, Mercenaria mercenaria. 31
- 9. 1986/87 Little Egg Harbor Bay Shellfish Inventory: composite length-percent-frequency distribution graph. 32
- 10. 2001 Little Egg Harbor Bay Shellfish Inventory: composite length-percent-frequency distribution graph. 33
- 11. 1986/87 Little Egg Harbor Bay Shellfish Inventory: recruitment indices (%) at stations with moderate and high abundances of hard clams. 34
- 12. 2001 Little Egg Harbor Bay Shellfish Inventory: recruitment indices (%) at station with moderate and high abundances of hard clams. 35 13a. 1986/87 Little Egg Harbor Bay Shellfish Inventory: mortality indices
(%) at all stations (northern Little Egg Harbor Bay). 36 13b. 1986/87 Little Egg Harbor Bay Shellfish Inventory: mortality indices
(%) at all stations (southern Little Egg Harbor Bay). 37 iv
14a. 2001 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%)
at all stations (northern Little Egg Harbor Bay). 38 14b. 2001 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%)
at all stations (southern Little Egg Harbor Bay). 39
- 15. 2001 Little Egg Harbor Bay Shellfish Inventory: distribution of blue mussels, Mtilus edulis. 40
- 16. 1986/87 Little Egg Harbor Bay Shellfish Inventory: distribution of blue mussels, Mytilus edulis. 41 V
ABSTRACT The New Jersey Bureau of Shellfisheries conducted a hard clam [Mercenariamercenaria (Linnus 1758)] stock assessment of Little Egg Harbor Bay. The Bureau sampled 194 stations from 16 July to 31 August 2001 using a hydraulic dredge to determine the bay's standing stock and relative distribution of hard clams. The hard clam resource in Little Egg Harbor Bay is estimated at 64.8 million clams, a decrease of over 67% from 1986/87, the last time a comprehensive shellfish survey was conducted in the bay. The decline in hard clam abundance per station between the two survey years was significant (P << 0.0002, P << 0.0002, P
< 0. 0001 and P < 0.0001). The mean size of hard clanms collected in 2001 was 78.9 mm and represented a significant increase from 1986/87's mean size of 74.6 mm (P < 0. 0002).
Recruitment indices, based on a percentage of hard clams between 30 and 37 nmm collected at a specific site as compared to all sized clams collected at the same site, were significantly lower in 2001 than in 1986/87 (P = 0.025). Mortality estimates were significantly greater in 2001 than in 1986/87 (P << 0.0002).
The bay contains an estimated 6,320 acres of submerged aquatic vegetation (SAV), a decrease of approximately 360 acres from 1986/87. However, there was no significant difference between the ratios of stations containing versus not containing SAV in 1986/87 versus 2001 (P ;'0.3576).
This study represents the first comprehensive shellfish survey of Little Egg Harbor Bay since 1986/87 and points to the importance of the availability of current-and quantitative stock estimates. This work represents an important step in the management of the bay's hard clam resource and should be followed by subsequent monitoring efforts.
INTRODUCTION Little. Egg Harbor Bay (Ocean County) has historically been one of New Jersey's most productive estuaries for hard clams, Mereenaria mercenaria,but reports from recreational and commercial sheilfishermen indicate that stocks are down significantly. Recent "brown tide" events caused by Aureococcus anophagefferenshave been hypothesized as causative agents in this reported decline. In New York, three years of successive brown tides have been implicated as the cause of extensive adult scallop [Argopecten irradians(Lamarck 1819)] mortality and severely limited larval recruitment (Tettelbach and Wenczel 1993). The bay scallop comprised a multimillion-dollar fishery in Long Island, New York prior to the first occurrence of A.
anophagefferens algal blooms (Tettelbach and Wenczel 1993). Montagna et al. (1993) report that brown tides are known to have had catastrophic effects on bivalves. Effects have ranged from reproductive or recruitment failures, to adverse impacts on feeding, to toxic effects, in which mass mortalities of shellfish were usually reported (Montagna et al. 1993, and references therein).
A hard clam stock assessment has not been performed in Little Egg Harbor Bay since 1986/87 when the New Jersey Bureau of Shelifisheries sampled approximately 200 stations in Little Egg Harbor Bay as part of its Estuarine Shellfish Research and Inventory Program (ESRIP). The ESRIP was terminated in 1988 when legislative changes made such work ineligible for the 50% federal funding which had facilitated a comprehensive shellfish survey from Raritan Bay to Great Bay. Funding provided via the New Jersey Department of Environmental Protection's environmental indicator efforts provided a sorely needed hard clam I
stock assessment for Little Egg Harbor Bay, which is essential to the Department's efforts to monitor, maintain and enhance the status of New Jersey's coastal ecosystem.
The purpose of this survey was to assess the standing stock, distribution and relative abundance of the hard clamr, Afercenaria mercenaria,in Little Egg Harbor Bay in 2001.
Quantitative and qualitative comparisons are made between this survey and an identical survey conducted in 1986/87, without inference as to what happened in the years prior to or in between these surveys. Another goal of this survey was to describe the distribution of submerged aquatic vegetation (SAV) species in Little Egg Harbor Bay and, again, compare these findings to those reported in 1986/87.
MATERIALS AND METHODS Study Site All fieldwork was conducted in Little Egg Harbor Bay, Ocean County, New Jersey (Figure 1). Little Egg Harbor Bay is one of three shallow microtidal bays that comprise the Barnegat Bay - Little Egg Harbor estuarine system (Bamegat Bay Estuary Program 1999).
Seawater enters the system through the Point Pleasant Canal, Barnegat Inlet and Little Egg Inlet (Barnegat Bay Estuary Program 1999).
Sampling Quantitative sampling was conducted from 16 July 2001 to 3.1 August 2001 in Little Egg Harbor Bay. All stations were sampled using the Research Vessel Notata: a 32-foot long, Chesapeake dead rise style vessel equipped with a hydraulic dredge. The dredge is equipped with a 12-inch wide blade that cuts approximately 4-inches into the substrate. The dredge uses water jets to loosen the bottom sediments ahead of the digging blade and to expel sediments through the body of the dredge (see Ropes and Martin 1960). Water is supplied to the jets through a 3-inch hose attached to a water pump on the deck of the vessel. At 35-40 pounds of pressure per square inch the pump delivers approximately 300 gallons of water per minute. The dredge is designed to collect and retain all hard clams 30 millineters (mm) in length or greater, therefore, clams less than 30 mm are not included in any analyses.
The dredge is deployed and retrieved via a 3/8-inch stainless steel wire cable attached to the main haul back winch on the vessel. The actual towing for sample collection was done with a 3/4-inch polypropylene graduated line.
Sampling protocols were similar to those used in the Bureau's 1986/87 shellfish survey of the same area (see Joseph 1987). Specifically, a systematic sampling design was employed.
The original sampling design was not created to look specifically at statistical changes from year to year per se, but in large part, to depict the distribution and abundance of commercially valuable munluscan shellfish within New Jersey's coastal estuaries (Joseph 1987). Stations sampled for the 2001 inventory wvere identical to those sampled in 1986/87 except for 31 of the 194 (16.0%) stations where it was not practicable due to recent obstructions, changes in bathymetry, aquaculture lease areas or submerged telecommunication/electric cable areas, in which case stations were relocated as close to the original stations as feasible (range: 138' to 1,503' away from original stations; x = 432'). As in the original survey, station locations were established at 1/2/-mnile intervals offset along east-west transects Y4-mile apart such that stations on adjacent transects were approximately 0.35 miles apart (see Figure 2, below). All stations were located using a Northstar 951X Differential GPS receiver chart plotter.
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After station position was established, a buoy was placed overboard to ensure the maintenance of the boat's position throughout sampling operations at each station. Following deployment of the buoy, water samples were collected with a Kenmmerer water sampler (at the first and last stations sampled in a day) for later analysis of dissolved oxygen, salinity and pH at the New Jersey Division of Fish and Wildlife's Nacote Creek Research Laboratory, Port Republic, New Jersey. Air and water temperatures (surface and bottom) were recorded from a mercury thermometer in the field. Dissolved oxygen was determined by Winkler titration.
Salinities were determined by a hand-held refiractometer and pH readings were obtained using colorimetric visual analyses against know standards (Taylor slide comparator).
FIG. 2. Schematic of systematic sampling design grid.
'/2 Mile W - dam np~g I 1/4mfle h
- ml0.35 Nor nmiles Following collection of water samples, water depth was recorded from a Lowrance 3200e Computer Sonar unit and the towline length determined accordingly. A towline length-to-depth ratio of 4:1 was utilized, although, in several instances it was not possible to maintain this ratio because of water depth and water supply hose limitations (100 feet). In those instances, a ratio of 3:1 was maintained. The towline length-to-depth ratio was never less than 3:1.
Prior to each tow, the substrate was probed with a clam rake handle in order to assist with the determination of dredge nozzle selection. In hard substrates, the forward nozzles were opened and back nozzles closed. In soft substrates, the forward nozzles were closed and back nozzles opened. These nozzle positions have previously been determined to yield optimal dredge efficiency (McCloy and Joseph 1983). Upon dredge nozzle adjustment,. one 100-foot tow was made. It was assumed that one tow was representative of a larger area (i.e., an entire sampling cell). Unfortunately there are no data to either support or refute this assumption - limitations on time and funding precluded an investigation. However, to minimize this source of estimation error, sampling frequency was increased to the maximum extent practicable (see Figure 2).
The 100-foot distance was measured by paying out a graduated line while towing the dredge. In bottoms with a high percentage of clay, submerged obstructions or submerged aquatic vegetation (SAV), where it was not possible to tow the entire .100 feet, tows were shortened and the length of the tow recorded. In instances where it was suspected that the dredge was not fishing properly due to low water pump pressure, dredge knife obstruction or erratic tow speeds for example, the tow was repeated until these concerns were resolved. In all cases, at the end of the measured tow, the vessel was held as stationary as possible until the dredge was raised off the bottom to prevent sampling more than the desired area.
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The dredge catch was deposited on a culling table for sorting and counting. All live hard clams and paired hard clam valves ("boxes") collected in each tow were counted and measured along their anterior-posterior axis to the nearest millieter using vernier calipers. Hard clams were graded into the following size categories: "sublegals" (30-37 ram), "littlenecks" (38-55 nmm), "cherrystones" (56-76 nrm) and "chowders". (> 76 mm). Hard clam abundance indices (catchper tow) for each station are expressed in terms of number per square feet. Observations were also made on the presence and number of other animal and plant species collected in the dredge (e.g., submerged aquatic vegetation and clam predators). Distribution charts of commercially important species (e.g., Mercenariamercenariaand Mytilus edulis) were developed.
PopulationSize/Age Structure A composite (the sumn of all clams measured) length-percent-frequency distribution graph was constructed by appropriately grouping all hard clamn lengths measured in the bay. Lengths were combined into three-millimeter groupings (starting at, but not including, 29 mm) as was done in 1986/87's survey; again, the dredge is designed to retain clams 30 mm in length and greater. The midpoints of each size grouping were plotted on the x-axis of the distribution graphs. Low clam abundances precluded preparation of length-percent-frequency distributions at all individual stations (all n < 100).
MereenariaDistributionandAbundance Estimation Spatial autocorrelation among stations was examined though the software module "EnvironmentalStats for S-Plus."
For the purpose of delineating relative abundance and distribution patterns of the hard clamn resource, four classifications of none (0.00 Mercenariafoot-2 ), occurrence (0.01-0.19 Mercenariafooto2 ), moderate abundance (0.20-0.49 Mercenariafoot-2 ), and high abundance
(>_0.50 Mercenariafoot-2 ) were established at each station after the data had been adjusted for the efficiency of the dredge (see below). The abundance categories selected equated with those used in the Bureau's 1986/87 survey.
For the purpose of calculating stock estimates of the hard clam resource, the following abundance classification intervals were established: (0.00), (0.01-0.05), (0.06-0.11), (0.12-0.49),
(0.50-0.99), (1.00-1.99) and (>_2.00) Mercenariafoot-f2 . The abundance categories matched the intervals used in the Bureau's 1986/87 survey. Adjacent stations within the same abundance category listed were grouped together and a mean abundance for that area determined by utilizing the Mercenariaabundance means of the individual stations. The mean abundance was then applied to the size of the area to yield the standing stock estimate for that particular area.
ArcView Geographic Information System (GIS) (2000) was utilized to estimate the size of the individual areas in feet 2. By summing the small areas, a resource estimate of the bay was developed. A 95% confidence interval was placed around the estimate (see below).
The Bureau of Shellfisheries conducted a separate study hi Raritan Bay to assess the efficiency of the Bureau's dredge (Celestino 2003). Under ideal conditions, the study would have been conducted in Little Egg Harbor Bay, but practical considerations precluded this from occurring (e.g., very low abundances of clams at most stations).
The Bureau examined the dredge's efficiency in each of five substrates (Table 1, below) using a mixed-model, hierarchical, two-way ANOVA, While other substrates were encountered, those selected represented the most frequently encountered. Three replicates were collected from 4
TABLE 1. Estimates of dredge efficiency among five substrates examined.
Substrate Efficiency (%)
Sand 67.8 Mud & Shell 84.8 Sand & Gravel 91.6 Mud & Sand 95.6 Mud 100.0 each substrate; the number of replicates was chosen a priori such that the denominator of the F ratio had at least six degrees of freedom (Hicks and Turner 1999). The model used for analysis was:
Yy= , + S! + -F-C k(0"), where Ii = a common effect for the entire experiment, Si substrate, Lj() = station within substrate, and & k(i) = the error estimate. The model did not allow for an analysis of variance among the stations within each substrate [Lji]; this is not a concern as the factor of interest was substrate (Si). The results of the analysis indicated a "marginally" significant difference among the five substrates (F 4,.o = 3.51, P = 0. 05).
It is important to note that the experimental design looked at a necessarily limited number of variables (e.g., substrate). Factors other than those examined could potentially influence the dredge's efficiency. Given the myriad factors that could affect dredge efficiency, the relatively small sample size, hard clam population dynamics, and thenmarginally significant result, it was decided to pool all efficiency estimates into a grand arithmetic mean with a 95% confidence interval. While this rationale has its drawbacks, it permits justifiable adjustment of raw data without quantitative analysis of substrate types, which would be time and cost prohibitive.
(Separate efficiency estimates based on substrate composition would require a quantitative decision based on subjective criteria; that is, application of a specific efficiency estimate to qualitatively different substrates - qualitatively different without sediment grain size analysis).
The dredge had an overall mean efficiency of 88.0% (+/-7.7%); all hard clam raw abundances were therefore increased by a factor of 1.137 (100 + 88.0%). However, for purposes of the present report, several analyses were conducted (see StatisticalAnalyses: Mercenaria abundance, below) to ensure that interpretation of the dredge efficiency results was not affecting the results or conclusions of the present paper. For more detail on the methods, analysis and interpretation of the dredge efficiency study please refer to Celestino (2003).
MercenariaMortality An index of natural hard clam mortality was determined at each station. This index was based upon the percentage of empty paired valves ("boxes") in the entire sample of paired valves and live clams: Mortality = { [(no. of boxes at station i) + (no. of boxes at station i + no. of live Mercenariaat station i)] x 100%}, for i 1,..... 94. Our mortality index is independent of age, size, and gender of Mercenaria.
MercenariaRecruitment For the purpose of this study, recruitment is defined as the percentage of clams entering the fishery at the legal size of 38 mm in length. To estimate annual recruitment, "sublegals" (Mercenariacollected between 30 and 37 mm in length) represented a single year class and would thus be expected to be recruited into the fishery within the coming year. The recruitment index per station was calculated as; {[(no. of Mercenariacollected between 30 and 37 mm at station i) + (total no. of Mercenariacollected at station i)] x 100%}, for i = 1 , ... 194. The total 5
number of sublegals estimated to be present in the bay is also reported. As in 1986/87's study,.
data from areas of occurrence (abundance < 0.20 Mercenaria.foot-2) were not taken into.
consideration when calculating recruitment indices due to concernsrelated to interpretation of small sample sizes.
StatisticalAnalyses: Mercenariaabundance I. Comparisonof Mercenariaabundances between 1986/187 and 2001 with dredge efficiency appliedto both datasets:
A single dredge effiCiency adjustment factor (i.e., 1.137- see above) was applied to all Mercenariaabundance data from both surveys for which paired data exists [i.e., "paired data" the same station was sampled in 1986/87 and 2001; stations added or deleted in 2001 would not have a "companion" station from 1986/87, and are consequently omitted from these analyses - 7 of 194 stations did not have a companion (.,. N= 187)]. Because the data are paired, and therefore not independent, Wilcoxon's distribution-free signed rank test for paired replicates was employed. The null hypothesis is that there is no shill in location (median) due to treatment (Hollander and Wolfe 1999). Because there were tied values among the data, the test is only approximate, and not exactly of significance level a [an exact level a test statistic in the tied setting requires deriving the exact conditional distribution of the test statistic (TV) which has, in this case, 1.92 x 10S possible outcomes] (Hollander and Wolfe 1999). A point estimator associated with Wilcoxon's signed rank test statistic was calculated to provide some measure of the magnitude of change in Mercenaria abundance. Finally, a distribution-free confidence interval around the point estimator based on Wilcoxon's signed rank test was calculated.
II. Comparison of Mercenariaabundancesbetween 1986/87 and 2001 with dredge efficiency appliedto one dataset:
The previous analysis assumes that the dredge efficiency was the same in 1986/87 as it was in 2001. This is a fair assumption as the exact same equipment (e.g., vessel, water pump, and dredge) was employed, however, it is possible that the dredge efficiency did change over time and that any statistical differences arising in the analyses are a result of a change in the dredge's efficiency and not in the abundance of Mercenaria.To account for the possibility that the dredge's efficiency decreased over time, the dredge efficiency correction factor was applied only to data collected in 2001 - it was therefore assumed that the dredge was 100% efficient in 1986/87, resulting in a conservative test (i.e., this assumption examines the smallest possible differences in Mercenariaabundance - therefore, if this analysis results in a significant difference, all other efficiency permutations would as well). Wilcoxon's distribution-free signed rank test for paired replicates was conducted.
III Comparisonof Mercenariaabundances between 1986/87 and 2001 with substrate-specific dredge efficiencies appliedto both data sets:
To explore the possibility that observed differences in Mercenariaabundance between the two survey years were due to the dredge operating at different efficiencies in different substrates (see Table 1 on page 5), substrate-specific efficiency correction factors were applied to Mercenariaabundances at individual stations based on their field-assigned substrate classification. That is, Mercenariaabundances were multiplied by 1.475 (100 + 67.8%; see Table 1) if the substrate at a given station was classified as "sand," a correction factor of 1. 179 (100 + 84.8%; see Table 1) was applied to Mercenariaabundance if the substrate at a station was classified as "mud and shell," and so on though a correction factor of 1.000 (100- 100.0%; see Table 1) for substrates classified as "mud."
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Stations were "assigned" substrates in two fashions: 1) substrates, as recorded on data sheets in the field, were interpreted literally such that if a substrate was not field-classified explicitly as one of the types listed in Table 1, data for that station was not included in the analysis; consequently, N 40 using this method. 2) Substrates were interpreted more liberally so that, for example, substrates field-classified as "hard sand" or "soft mud". were assigned efficiencies corresponding to those of "sand" and "mud," respectively. The nozzle position selected at a station and recorded on the data sheet aided with interpretation. Using this method, N = 45 for this analysis.
" As in previous analyses, Wilcoxon's distribution-free signed rank test for paired replicates was employed. See SAS (19.90) for details of calculation methods.
Note on Mercenariaabundance analyses: because multiple tests are being performed (i. e.,
Mercenariaabundance analyses I, II and III), significance levels need to be corrected for maintenance of experimentwise error rate levels. This was done using Bonferroni corrections
[seeRice (1990)].
StatisticalAnalysis: Mercenariamortality Wilcoxon's. distribution-free signed rank test for paired replicates was used to analyze the mortality indices from 1986/87 to 2001 - the large sample approximation was used [see StatisticalAnalysis: MercenariaI above for details]. A distribution-free point estimator and confidence interval were developed as well (see above for details).
StatisticalAnalvsis: Mercenariarecruitment Wilcoxon's distribution-free signed rank test for paired replicates was used to analyze the recruitment indices from 1986/87 to 2001 - an exact test (not large sample approximation) was used. A distribution-free point estimator and confidence interval were developed as well (see above for details). Only stations where Mercenariaabundances were > 0.20 clams foot" were incorporated into the analysis, therefore total sample size is 14 (i.e., only 14 pairs of stations contained Mercenaria abundances Ž_0.20 clanms foot-2 in both survey years).
StatisticalAnalysis: Mercenariasize/age Wilcoxon's distribution-free signed rank test for paired replicates was used to analyze mean Mercenarialengths from 1986/87 to 2001 - the large sample approximation was used (see StatisticalAnalvsis: Mercenaria1 above for details). A distribution-free point estimator and confidence interval were developed as well (see above for details). Only stations where Mercenariawere collected during both surveys were incorporated into analyses, therefore total sample size is 120 (i.e., only 120 pairs of stations contained > 1 Mercenariaper station in both survey years). Stations where only > 1 Mercenariawere collected were included in analyses because 0 clams collected results in a "mean size" of 0/0 (= undefined).
Submerged Aquatic Vegetation (SA P) Distribution To develop the total acreage of SAV in Little Egg Harbor Bay, SAV was determined to be either present or absent based on the same dredge sample used to collect hard clams. No quantitative description was made in the field with respect to SAV acreage, only presence or absence. For distributional analysis, when SAV was collected at a station (i.e., present), a polygon was drawn around said station using ArcView GIS software (2000). Said polygon encompassed any adjacent stations where SAV was also collected. The analysis requires the same assumption as the Mercenaria.analysis; specifically, that SAV's presence (or absence) is constant within a given polygon [water depths aided interpolation between stations (e,g., it was 7
assumed that water depths in navigation channels would preclude the presence of SAV)]. This seems reasonable given station location proximity. Total acreage was derived by sumrming individual polygon acreages.
StatisticalAnalysis: Submerged Aquatic Vegetation The null hypothesis (Ho) asserts that the proportions of stations containing versus not containirig SAV did not change from 1986/87 to 2001 (Figure 3). H, was tested using McNemar's Test. This test is nonparametric and is appropriate for categorical data based on dependent samples (Hollander and Wolfe 1999). Our data for this analysis are paired and therefore constitute dependent data. Taking the pairing into account will provide the best chance of detecting a departure from the null hypothesis (Hollander and Wolfe 1999).
Because not all stations between the two sampling years had a direct paired station, total sample size for this analysis was 184.
FIG. 3. Conceptualization of null hypothesis for submerged aquatic vegetation (SAV) analysis.
1986/87 SAV Present SAV Absent SAV Present O1 012 SAV Absent 021 022 H1:p 12 P21 RESULTS-Description of Study Site Substrates qualitatively ranged from hard sand to soft mud. All locations were characterized by having salinities between 26%o and 31%o (x = 29.2%o; SD = 1.4%o), water temperatures between 230 and 30'C (x = 26°C; SD = 1.7°C) and air temperatures between 21' and 33.5°C (x= 26'C; SD = 3.5°C). Physical and chemical data are summarized in Table 2.
Submerged Aczuatic Veiyetation In 2001, a total of 6,320 acres in Little TABLE 3. Comparison of acres of submerged aquatic vegetation (SAV) mapped in Little Egg Harbor Bay Egg Harbor Bay was mapped as containing from the 1986/87 and 2001 surveys.
submerged aquatic vegetation (SAV), compared to 6,683 acres in 1986/87 (Table 3, to the right).
Survey Year Acres of SAV Figures 4 and 5 depict the distribution of SAVs in Little Egg Harbor Bay in 1986/87 and 2001, 1986/87 6,683I respectively (the 1986/87 SAV distribution chart is provided for illustrative purposes only). In 2001 6,320 200 1, Zostera marina (eelgrass) was the 8
dominant SAV collected; Ruppia niaritima(widgeon grass) was collected at only three stations:
12.5, 83 and 173 (Figure 6, Table 4). SAV was collected in water up to 8 feet 'in depth (Table 4).
McNemar's Test indicated no significant difference between the proportions of stations containing versus not containing SAV in 1986/87 versus 2001 (d 0. 365, Pt *. 35760).
MercenariaAbundance and Distribution All Mercenaria data provided is adjusted for the dredge's efficiency unless otherwise specified.
All results must be interpreted in light of autocorrelation analyses that indicated that
,Alercenariaabundances were correlated within approximately 10,000 feet for 1986/87's survey.
The 2001 survey data showed a similar (but weaker) correlation, again within approximately 10,000 feet.
Station location, hard clam abundance, mean length, percent mortality, commercial size class percentages [including percent sublegals (the measure of recruitment for purposes of this study)], and presence/absence of SAV at each station are presented in Table 4. The locations of the 194 stations sampled are presented in Figure 6.
The hard clam resource in TABLE 5. Comparison of hard clam stock estimates in Little Egg Little Egg Harbor Bay (taking into Harbor Bay from the 1986/87 and 2001 hard clam surveys.
account the dredge's efficiency) is estimated at 64.8 (-5.2 / +6.2) 64,803,901 = 2001 stock estimate (clams) million clams (Table 5) - a cionservatve etmsTate conservative estimate of te a201 the ,476,066 = 1986/87 stock estimate (clams) resource (i.e., not taking into 136,672,165 - Difference in stock estimates (clams) account the dredge's efficiency) is 57.0 million clams. Stock estimates 67.8% Percent difference in stock estimates by commercial size class are presented in Table 6.
Table 7 depicts the number and percentage of stations sampled with no Mercenaria; low, moderate and high abundances of Mercenariain Little Egg Harbor Bay for both the 1986/87 and 2001 surveys.
Figures 7 and 8 depict the distribution and abundance of hard clams in Little Egg Harbor Bay in 1986/87 and 2001, respectively [NOTE: the 1986/87 chart shows unadjusted hard clam abundances (i.e., not adjusted for dredge efficiency), while the 2001 chart depicts dredge-efficiency adjusted abundances]. Hard clam abundances ranged from 0.00 to 0.75 clams foot-2 in 2001 (x= 0.09 clams foot 2 ; SD = 0.14 clams foot ) and from 0.00 to 2.98 clams foot 2 in 1986/87 (x = 0.28 clams foof 2; SD = 0.32 clams foot-2 ) (Table 8, below). Wilcoxon's signed rank test (on all dredge efficiency adjusted data) indicated a significant decline in hard clam abundances in 1986/87 versus 2001 (T* = -9.068, P << 0.0002). The mean decline (0) is estimatedat -0.14 clams foot-2 [Pr (-0.18 clamsfootI < 0 <-0.]] clainsfoof2) 95%].
Analysis of dredge efficiency adjusted 2001 data and unadjusted 1986/87 data (see Statistical Analysis: MercenariaabundmaceII, described above) also indicated a significant decline in hard clam abundances between the two surveys (T* = -8.570, P << 0.0002). Finally, the analysis of substrate-specific dredge efficiency adjusted 1986/87 and 2001 data (see StatisticalAnalysis:
MercenariaabundanceIII, described above) also indicated a significant decline in hard clam 9
abundances between the two surveys for both literal (S -290.5, P < 0. 0001) and liberal (S
-364.5, P < 0. 0001) substrate interpretations.
TABLE.8. Comparison of hard clam abundance statistics from Little Egg Harbor Bay between the 1986/87 and 2001 surveys.
I-I Summary Statistic Average Abundance 1986/87 clams foot-2 0.28 2001 clams foot-2 0.09 Minimum Abundance 0.00 0.00 Maximum Abundance 2.98 0.75 Standard Deviation 0.32 0.14 Population Structure To give an overall description of the hard TABLE 9. Comparison of hard clam population clam population in Little Egg Harbor Bay, composite statistics (number collected, mean size, and (the sum of all clams measured) length-percent- standard deviation of sizes) in Little Egg Harbor frequency distribution graphs are presented in Figures Bay for the 1986/87 and 2001 surveys.
9 and 10 for the surveys conducted in 1986/87 and 1986/87 2001 2001, respectively. The total number of clams collected n 939 in each survey, mean lengths and standard deviations n are listed in Table 9, to the right. Wilcoxon's signed x 74.6 mm. 78.9 mm rank test indicated a significant increase in the mean SD 11.0 mm 15.3 mm size of hard clams collected in 1986/87 versus 2001 (T* = 5.099, P < 0. 0002). The mean increase (0) is estimated at 6.9 mm [Pr (4.82 mm < 0 <
9.12 mm) = 95%]1.
Recruitment Recruitment indices were variable among stations in 2001, ranging from 0.0% to 12.1%
with a mean of 1.2% in 2001, compared to a range of 0.0% to 34.6% with a mean of 3.9% in 1986/87 (Tables 4 and 10). Wilcoxon's signed rank test indicated a significant decline in the recruitment indices in 1986/87 versus 2001 (T = 21.0, P = 0.025). The mean decline (0) is estimated at -1.55% [Pr (-3.35% < 0< 0.00%) = 95.2%]. Figures 11 and 12 spatially depict recruitment indices in Little Egg Harbor Bay in 1986/87 and 2001, respectively.
Mortality The average hard clam mortality for Little Egg Harbor Bay in 2001 was 39.7% compared to 11.6% in 1986/87 (Table 10). Mortalities were very variable, ranging from 0% to 100% in both surveys (Tables 10 and 11). Wilcoxon's signed rank test indicated a significant increase in mortality indices in 1986/87 versus 2001 (T* = 8.165, P << 0.0002). The mean increase (0) is estimated at 28.97% [Pr (21.85% < 0 < 35.23%) = 95%]. Mortality indices are spatially depicted in Figures 13a and 13b for the 1986/87 survey, and in Figures 14a and 14b for the 2001 survey. Table 12 lists abundances of some common clam predators collected in the survey potentially contributing to juvenile Mercenariamortality (this table also lists other organisms collected during the 2001 survey).
10
TABLE 11. Comparison ofinortality index intervals between the 1986/87 and 2001 surveys.
I Mortality Index 1986/87 (number of stations) 2001 .
(number of stations)
_<25% 162 94 26-50% 24 37.
51-75% 2 15
> 75% 1 48 Associated Commercial Species' Abundance and Distribution In 2001 blue mussels [Mytilus edulis (Linneus 1758)] were collected at 14 stations (Table 4, Figure 15). The distribution of Mytilus from 1986/87 is provided in Figure 16 for comparison. In both surveys, Mytilus were collected only in the southern portions of the bay..
Soft clams (Mya arenariaLinrmaus 1758) were not collected during the 1986/87 or 2001 surveys.
Quantitative estimates of blue mussels are not provided because the dredge was not designed to efficiently retain, the small sizes that were observed. Length-percent-frequency distributions were not created, as insufficient numbers were collected or measured (n < 100 per station). However, of the mussels retained in the dredge, abundances ranged from 0.02 to 162 mussels foot-2 and had a mean length of 28.1 mm (SEM 4.7 mm).-
DISCUSSION AND CONCLUSIONS Several indicators uncovered in this study point to causes for concern. However, all results must be viewed in light of the fact that data are not available for Mercenariapopulation dynamics for the years prior to or in between the two surveys discussed in this report.
Consequently, definitive statements cannot be made regarding interpretation of observed differences between the two surveys. However, as previously mentioned, the purpose of the study was to assess the standing stock, distribution and abundance of the hard clam in Little Egg Harbor Bay and compare those metrics with hard clam population metrics from a survey conducted in 1986/87, without making any inference as to what happened in the years prior to or in between these two surveys.
The estimated standing stock of hard clams in Little Egg Harbor Bay is 64.8 million clams, a decline of over 67% friom 1986/87's stock estimate (Table 5). Table 8 indicates that average abundances (per station sampled) in the bay have decreased by two thirds, and quantitative examinationsof hard clam abundances per station (between survey years) indicated that the decline was significant (four different tests indicated: P << 0. 0002, P << 0. 0002, P < 0. 0001 and P < 0. 0001).
In general, the 2001 survey found bay-wide declines in the abundance of hard clams.
Some areas of prominent decline include a large, high abundance area (-2,060 acres) present in the southern section of the bay in 1986/87 that has been reduced to patches of zero, low and moderate abundances of hard clams (Figures 7 and 8). In 2001, only four stations contained high abundances of hard clams compared to 32 stations in 1986/87 (Table 7). The western-most parts of the bay that previously contained hard clams predominantly in the "occurrence" classification have largely been reduced to zero abundance areas (Figures 7 and 8).
11
Table 7 indicates that stations with low abundances of hardclams were the most common.
in both 1986/87 and 2001. Aianningly, the percentage of stations containing no claims increased from 3.2% in 1986/87 to 35.1% in 2001. Almost 47% of the stations sampled in 1986/87 had moderate or high abundances of Mercenaria,compared to 14% in 2001 (Table 7).
Several results suggest little recruitment in Little Egg Harbor Bay. Stock estimates by commercial size class (Table 6) indicate a preponderance of "chowder" clams in the bay (66.3%). Sublegal sized clams represented the smallest percentage of clamns (1.7%). Analysis of mean sizes of Mercenariacollected in 1986/87 and 2001 indicated that clams were significantly larger in 2001 than in 1986/87 (on average +-7 mm). Inspection of the 2001 composite length-percent-frequency distribution graph (Figure 10) revealed a relatively "old" population, with a dominant size of approximately 90 mm (chowders). It appears as though a minimum of nine year classeswas present in the bay in 2001. Comparison of the distribution graphs from 1986/87 and 2001 (Figures 9 and 10, respectively) shows a population growing older with little recruitment -
a conclusion supported by the results reported above. Additionally, with the exception of four stations, all areas of the bay exhibited 0% recruitment in 2001. Recent studies have demonstrated the importance of relatively close proximity of adults to successful reproduction among some marine species that spawn in the water column (Levitan et al. 1992, as cited by Fegley 2001).
Under conditions where large numbers of widely dispersed spawners occur, low fertilization rates are likely (Fegley 2001).
Mortality estimates have increased from 11.6% in .1986/87 to 39.7% in 2001. In general, mortality rates appeared to be consistently high in the western portions of the bay in 2001 (Figures 14a and 14b), especially from Cedar Run south to the extensive aquaculture lease area of Tuckerton. While production data are not available for aquaculture leases, an investigation into lease occupancy indicated that -70 leases were occupied in the Tuckerton area in 1986/87, while only -50 were occupied in 2001 (a decline of approximately 29%). Reasons for the decline in occupancy have been at least partially contributed to marketability issues related to discolored clam meats in the area (N. Loveland. NJDEP, pers. comm. 2002).
Mortalities in 1986/87 were, in general, lower than in 2001. For example, only three stations in 1986/87 had mortality rates > 50%, whereas 63 stations did in 2001 (see Table 11).
A review of the literature uncovered no information on the amount of time Mercenaria paired valves remain intact. Consequently, the mortality index is of an indeterminate period of time. It is possible that the reason mortality estimates were higher in 2001 is that they include 1986/87's estimates as well.
Observed abundance of the common clam predators such as conchs (Busycotypus canaliculatusand Busycon carica), moon snails (Polinicesduplicatus), oyster drills (Urosalpinx cinerea), lady crabs (Ovalipes ocellatus), blue crabs (Callinectes sapidus), sea stars (Asterias forbesi), horseshoe crabs (Limulus polyphemus), and xanthid crabs were relatively tow (Table 12). Rock crabs (Cancer irroratus)were relatively abundant (0.30 crabs feet -2; Table 12).
Finally, with respect to Little Egg Harbor Bay submerged aquatic vegetation (SAV),
while there was a decline of approximately 5% in the total estimated acreage in 1986/87 to 2001, McNemar's Test indicated no significant difference between the proportions of stations containing versus not containing SAV during this time (d = 0.365, P *0.3576). Nevertheless, some of the more prominent changes in SAV distribution include some fragmentation of the extensive beds located in the northern half of the bay (Figures 4 and 5). Some SAV was also absent in 2001 adjacent to Long Beach Island. However, SAV was collected in several areas in 2001 where it was not collected in 1986/87:
12
" Edge Cove,
" Dinner Point,
" Along the western side of Mordacai Island, and
- In the south-central portion of Little Egg Harbor Bay (e.g., Barrel Island).
This study represents the first comprehensive shellfish survey of Little Egg Harbor Bay since 1986/87 and points to the importance of the availability of current and quantitative stock estimates. Our conclusions are necessarily limited by the availability of data between the two surveys. This work represents an important step in the management of the bay's hard clam resource and should be followed by subsequent monitoring efforts.
While "brown tide" events have been hypothesized to be the causative agents responsible (entirely or in part) for hard clam declines, further work is needed to resolve this question.
Brown tides can affect shellfish populations through a variety of mechanisms (see Montagna el al 1993), however it is possible that non-bloom factors (sensu Montagna et al. 1993) are partly or wholly responsible. Despite the ecological and economic importance that can be attached to hard clam populations, little information has been gathered that provides insight into their dynamics (Fegley 2001).
ACKNOWLEDGEMENTS Considerable thanks are due to Babb, R., Beningo, D., Burns, C., DeAlteris, J., Downes Gastrich, M., Joseph, J., Kom, L., Miller, E., Normant, J., Reed, R., Resciniti, M., Sheth, N., and an anonymous reviewer.
This project was supported with funding from the New Jersey Department of Environmental Protection's Division of Science, Research and Technology.
LITERATURE CITED ArcView GIS. 2000. ArcView 3.2a. Environmental Systems Research Institute, Redlands, California, USA.
Barnegat Bay Estuary Program. 1999. The Scientific Characterization of the Bamegat Bay -
Little Egg Harbor Estuary and Watershed. Kennish, M. J. (ed). Institute of Marine and Coastal Sciences, New Brunswick, New Jersey, USA.
Celestino, M. 2003. Estimation of the efficiency of the New Jersey Bureau of Shellfisheries' hydraulic dredge. New Jersey Division of Fish and Wildlife, Bureau of Shellfisheries.
11 pp.
Fegley, S. R. 2001. Chapter 9: Demography and dynamics of hard clam populations. Pages 383-422 in J. N. Kraeuter, and M. Castagna, editors. Biology of the hard clam. Elsevier Science B.V., Amsterdam, Netherlands.
Hicks, C. R., and K. V. Turner. 1999. Fundamental concepts in the design of experiments. Oxford University Press. New York, NY, USA.
13
Hollander, M., and D. A. Wolfe. 1999. Nonparametric Statistical Methods, 2 nd ed. John Wiley &
Joseph, J. W. 1987. Inventory of New Jersey's Estuarine Shellfish Resources. United States Department of Commerce Project No. 3-405-R:2. 79pp.
Levitan, D. R., Sewell, M. A., and Chia, F. 1992. I-low distribution and abundance influence fertilization success in the sea urchin Strongylocentrotusfr'anciscanus,Ecology 73: 248-254.
McCloy, T. W., and J. W. Joseph. 1983. Inventory of New Jersey's Estuarine Shellfish Resources. United States Department of Commerce Project No. 3-332-R:3. 104pp.
Montagna, P. A., D. A. Stockwell, and R. D. Kalke. 1993. Dwarf surfclam (sic) Mulinia lateralis (Say, 1822) populations and feeding during the Texas brown tide event. Journalof Shellfish Research 12(2): 433-442.
Ropes, J. W., and C. E. Martin. 1960. The abundance and distribution of hard clams in Nantucket Sornd, Massachusetts, 1958. United States Fish and Wildlife Service Speci~l Scientific Report - Fisheries No. 354.
Rice, W. R. 1990. A consensus combified P-value test and the family-wide significance of component tests. Biometrics 46: 303-308.
SAS Institute Inc. 1990. SAS' Procedures Guide, Version 6, 3 rP ed. SAS Institute Inc., Cary, North Carolina, USA. 705pp.
Tettelbach, S. T. and P. Wenczel. 1993. Reseeding efforts and the status of the bay scallop Argopecten irradians(Lamarck, 1819) populations in New York following the
.14
Table 2. Physical and chemical data collected during the 2001 Little Egg Harbor Bay hard clam stock assessment.
LITTLE EGG HARBOR BAY Air Surface water Bottom water Surface Bottom Surface Bottom Surface Bottom Temperature Temperature Temperature Dissolved Oxygen Dissolved Oxygen Salinity Salinity pH pH (0C) (0C) (0c) (mg/I) (mg/I) (0/1) (Po)
Average 25.8 26.1 25.9 6.5 6.4 29.3 29.1 8.2 8.3 Minimum 21 23.5 .. 23 4.9 4.7 26 26 8.0 8.1 Maximum 33.5 30 29 7.8 9.5 31 31 8.4 8.4 Standard Deviation 3.5 1.8i 1.7 0.9 1.1 1.4 1.5 0A1 0.1 Count (n) 24 23 24 23 24 23 24 16 18
Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence of submerged aquatic vegetation (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Station Date Latitude Longitude Depth Abundanceadj** MeanLength Percent Percent Percent Percent Percent SAV8 Mytilus (feet) (clams/foot2 ) (mm) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?
LEHB-01-179 27-Aug-01 3935.00 74 16.33 8.0 0.11 89.0 0.00 0.00 0.00 0.00 100.00 0 0 LEHBý01-180 27-Aug-01 39 35.00 74 16.97 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-181 27-Au -01 3935.25 7417.29 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0. 0 LEHB-01-182 27-Aug-01 3935.50 74 17.61 8.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0. 0 LEHB-01-183 27-Aug-01 39.35.50 74 18.26 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-184 27-Aug-01 3935.70 74 18.40 7.0. 0.00 n/a 0.00 0.00 0.00 0.00 c.00 + 0 LEHB-01-185 27-Aug-01 3936.25 74 17.94 7.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-186 27-Aug-01 3935.50 74 18.90 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-187 27-Aug-01 3934.972 74 19.463 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-188 31-Aug-01 3934.500 74 15.030 3.0 0.04 81.0 0.00 0.00 0.00 0.00 100.00 + 0 LEHB-01-189 31-Aug-01 39 34.500. 74 15.350 3.0 0.26 85.7 " 12.50 0.00 14.29 0.00 85.71 . + 0 LEHB-01-190 31-Aug-01 3932.000 74 16.330 15.0 0.00 n/a 0.00 0.00 0.00. 0.00 0.00 0 +
LEHB-01-191 31-Aug-01 3931.75 74 16.65 14.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-192 31-Aug-01 3931.500 74 17.050 15.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 +
- .LEHB-01-018 tow repeated on 8/3/01 (water depth = 4) due to low water pump pressure on 7/17/01.
LEHB-01-043 tow repeated on 813/01 (water depth = 5) due to low water pump pressure on 7/17/01.
LEHB-01-062 tow repeated on 8/1801 (water depth = 5').
LEHB-01-11I additional tow performed on 8/9101 (water depth= 4') outside of cable area at 39*33.563, 74' 15.662 (approximately 0.07 nm from original coordinates) due to suspected abandoned telecommunications cable impeding dredge.
Station LEHB-01-160 deleted - station located within an aquaculture lease.
ASAV: + = Zostera marina collected, 0 = Z. marina hot collected, Ruppia = Ruppia maritime collected.
Abundance.c, = Har d clam abundances adjusted for dredge efficiency.
Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presencelabsence of submerged aquatic vegetation (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Station Date Latitude Longitude Depth Abundanceadj** Mean Length Percent Percent Percent Percent Percent SAV" Mytilus (feet) (clams/foot2 ) (mm) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?*
LEHB-01-142 21-Aug-01 3932.455 74 16.982 3.5 0.14 45.5 42.86 25.00 58.33 16.67 0.00 0 +
LEHB-01-143 21-Aug-01 3932.75 74 17.29 3.0 0.66 55.7 9.38 12,07 48.28 29.31 10.34 0 0 LEHB-01-144 21-Aug-01 3932.00 74 17.71 8.0 0.03 63.0 50.00 0.00 0.00 100.00 0.00 0 +
LEHB-01-145 21-Aug-01 39 32.25 74 17.84 8.0 0.05 46.5 50.00 0.00 100.00 0.00 0.00 0 +
LEHB-01-146 21-Aug-01 39 32.25 74 17.29 8.0 0.02 30.0 50.00 100.00 0.00 0.00 0.00 0 +
LEHB-01-147 21-Aug-01 3931.75 74 17.29 7.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-148 22-Aug-01 3934.50 74 18.26 6.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-149 22-Aug-01 3934.50 74 18.90 6.0 0.02
- 90.0 83.33 0.00 0.00 0.00 100.00 0 0 LEHB-01-150 22-Aug-01 3934.36 7419.18 5.0 0.07 88.0 62.50 0.00 0.00 0.00 100.00 0 0 LEHB-01-151 22-Aug-01 39 34.063 74 19.988 4.0 0.25 84.5 35.29 0.00 0.00 18.18 81.82 0 0 LEHB-01-152 22-Aug-01 39 34.000 74 19.926 4.0 0.08 91.5 77.78 0.00 0.00 0.00 100.00 0 0 LEHB-01-153 22-Aug-01 39 33.75 74 19.87 5.0 0.13 81.6 0.00 6.67 13.33 6.67 73.33 0 0 LEHB-01-154 22-Aug-01 39 33.50 74 19.55 3.5 0.10 68.0 10.00 0.00 33.33 33.33 33.33 0 0 LEHB-01-155 23-Aug-01 3933.00 74 18.90 12.0 0.09 95.3 42.86 0.00 0.00 0.00 100.00 0 0 LEHB-01-156 22-Aug-01 39 33.25 74 18.65. 4.0 0.18 99.4 20.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-157 22-Aug-01 3933.50 74 18.90 3.0 0.05 80.3 33.33 25.00 0.00 0.00 75.00 0 0 LEHB-01-158 22-Aug-01 3933.75 7419.23 4.0 0.06 90.6 0.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-159 22-Aug-01 3933.25 74 19.23 4.0 0.02 90.0 50.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-161 22-Aug-01 3934.75 7420.20 6.0 0.48 71.4 22.22 0.00 4.76 66.67 28.57 0 0 LEHB-01-162 23-Aug-01 3932.75 74 18.58 5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-163 23-Aug-01 39 34.75 74 17.94 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-164 22-Aug-01 39 35.25 74 17.81 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-165 23-Aug-01 3934.875 74 17.440 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-166 23-Aug-01 39 34.75 74 17.29 8.0 0.01 60.0 95.00 0.00 0.00 100.00 0.00 0 0 LEHB-01-167 23-Aug-01 39 34.50 74 16.97 7.0 0.19 87.0 58.33 0.00 0.00 0.00 100.00 0 0 LEHB-01-168 23-Aug-01 39 34.75 74 16.65 7.0 0.23 86.1 44.44 0.00 0.00 0.00 100.00 0 0 LEHB-01-169 23-Aug-01 39 34.00 74 16.33 6.0 0.17 80.5 40.00 8.33 8.33 0.00 83.33 + 0 LEHB-01-170 23-Aug-01 3933.00 7416,33 5.0 0.49 92.5 18.75 0.00 8.33 0.00 91.67 + 0 LEHB-01-171 23-Aug-01 39 32.50 74 16.33 4.0 0.01 96.0 0.00 . 0.00 0.00 0.00 100,00 0 0 LEHB-01-172 23-Aug-01 3932.220 74 16.585 3.0 0.36 . 81.8 15.79 0.00 6.25 18.75 75.00 0 +
LEHB-01-173 23-Aug-01 3933.75 7414.95 3.0 0.00 n/a. 100.00 0.00 0.00 0.00 0.00 Ruppia only 0 LEHB-01-174 23-Aug-01 3933.55 7414.85 4.0 0.05 84.0 0.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-175 27-Aug-01 3934.25 74 14.39 4.0 0.14 85.5 45.45 0.00 0.00 16.67 83.33 + 0 LEHB-01-176 27-Aug-01 3934.25 74 16.01 8.0 0.42 . 82.1 8.33 . 0.00 9.09 0.00 90.91 0 0 LEHB-01-177 27-Aug-01 3934.50 74 16.33 8.0 0.26 82.7 0.00 0.00 14.29 0.00 85.71 0 0 LEHB-01-178 27-Aug-01 39 34.75 74 16.01 10.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0
of submerged aquatic vegetation Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Abundance,,d* Mean Length Percent Percent Percent Percent Percent SAV'W Mytilus Station Date Latitude Longitude Depth (feet) 2 (clams/foot ) (mm) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?
5.0 0.06 95.5 25.00 0,00 0,00 0.00 100.00 + 0 LEHB-01-106 8-Aug-01 39 33.50 74 16.33 4.0 0.38 92.9 13.16 0.00 3.03 0.00 96.97 0 0 LEHB-01-107 9-Aug-01 3933.25 74 16.01 0.05 88.5 0.00 0.00 0.00 50.00 50.00 + 0 LEHB-01-108 9-Aug-01 39 34.00 74 15.03 4.0 8.0 0.70 93.6 3.13 0,00 0.00 0.00 100.00 + 0 LEHB-01-109 27-AugO.1 39 34.25 74 15.25 8.0 0.03 39.0 0.00 0.00 100.00 0.00 0.00 0 +
LEHB-01-110 9-Aug-01 39 33.75 74 15.35 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-1.11* 9-Aug-01 39 33.50 74 15.67 6.0 0.11 108.0 0.00 0.00 0.00 0.00 100.00 0 +
LEHB-01-112 9-Aug-01 3933.00 74 15.67 8,0 0.01 48.0 0.00 0.00 100.00 0.00 0.00 0 0 LEHB-01-113 9-Aug-01 39 32.70 74 15.82 8.0 5.0 0.05 89.3 42.86 25.00 0.00 0.00 75.00 0 +
LEHB-01-114 9-Aug-01 3932.50 7415.74 6.0 0.08 90.0 0.00 0.00 0.00 0.00 100.00 0 +
LEHB-01-115 9-Aug-01 39 32.25 74 16.01 4.0 0.03 44.0 25.00 0.00 100.00 0,00 0.00 0 0 LEHB-01-116 9-Aug-01 3932.00 74 16.97 4.0 0.16 81.9 12.50 0.00 14.29 28.57 57.14 + 0 LEHB-01-117 9-Aug-01 3933.35 74 15.30 6.0 0.41 93.7 5.26 0.00 0.00 2.78 97.22 0 0 LEHB-01-118 9-Aug-01 3933.75 74 16.01 8.0 0.14 95.5 0.00 0.00 0.00 0.00 100.00 0 +
LEHB-01-119 9-Aug-01 3934.00 74 15.67 6.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-120 9-Aug-01 39 35.302 74 13.790 74 12.525 4.0 0.00 n0a 0.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-121 9-Aug-01 39 36.691 10.0 0.68 73.2 6.25 3.33 10.00 40.00 46.67 0 0 LEHB-01-122 14-Aug-01 39 36.282 74 12.798 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0,00 0 0 LEHB-01-123 14-Aug-01 39 36.00 74 16,33 8.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-124 14-Aug-01 39 36.25 74 16.65 4.0 0.00 n/a 50.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-125 14-Aug-01 39 36.50 74 16.97 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-126 14-Aug-01 39 36.25 74 17.29 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-127 14-Aug-01 39 36.00 74 16.97 8.0 9.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-128 .14-Aug-01 39 35.75 74 16.65 0,00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-129 14-Aug-01 39 35.50 74 16.33 7.0 4.0 0.43 89.1 18.37 0.00 0.00 0.00 100.00 0 0 LEHB-01-130 14-Aug-01 39 35.25 74 16.01 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-131 14-Aug-01 3935.25 74 16.65 0.02 96.0 83.33 0.00 0.00 0.00 100.00 0 0 LEHB-01-132 14-Aug-01 39 35.50 74 16.97 9.0 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-133 14-Aug-01 39 35.75 74 17.29 8.0 0.00 n/a 100.00 0,00 0.00 0.00 0.00 0 0 LEHB-01-134 14-Aug-01 3936.00 74 17.61 6.0 0.00 n/a 100.00 0,00 0.00 0.00 0.00 0 0 LEHB-01-135 14-Aug-01 39 36.00 74 18.26 7.0 0.00 n/a 100.00 0,00 0.00 0.00 0.00 0 0 LEHB-01-136 14-Aug-01 39 35.75 74 17.94 10.0 0.00 n/a 0.00 0,00 0.00 0.00 0.00 0 +
LEHB-01-137 21-Aug-01 3931.709 74 17,813 4.0 0.07 62.0 25.00 0.00 66.67 0.00 33.33 0 +
LEHB-01-138 21-Aug-01 39 32.50. 74 17.61 0.00 n/a 100.00 0.00 0.00 0.00 000 0 0 LEHB-01-139 21-Aug-01 39 32.60 7417.94 4.0 8.0 0.09 75.0 0.00 -0.00 25.00 25.00 50.00 0 0 LEHB-01-140 21-Aug-01 39 32.50 74 18.26 4.0 0.25 77.7 21.43 9.09 18.18 27.27 45.45 0 0 LEHB-01-141 21-Aug-01 39 32.769 74 16.709
Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence of submerged aquatic vegetation (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Station Date Latitude Longitude Depth Abundanceadj* Mean Length Percent Percent Percent Percent Percent SAVa Mytilus (feet) (clams/foot 2) (mrm) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?
LEHB-01-070 6-Aug-01 39 35.50 74 13.43 9.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-071 6-Aug-01 3935.25 7414.07 5.0 0.02 93.0. 66.67 0.00 0.00 0.00 100.00 + 0 LEHB-01-072 6-Aug-01 39 35.10 74.14.00 7.0 0.00 . n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-073 6-Aug-01 39 35.50 74 14.39 6.0 0.14 88.0 64.71 0.00 0.00 16.67 83.33 + 0 LEHB-01-074 6-Aug-01 39 35.50 74 15.03. 7.0 0.34 86.0 31.82 6.67 0.00 0.00 93.33 + 0 LEHB-01-075 6-Aug-01 39 35.75 74 14.71 5.0 0.02 87.0 50.00 0.00 0.00 0.00 100.00 + 0 LEHB-01-076 6-Aug-01 39 36.00 74 14.39 5.0 0.08 71.6 27.78 0.00 0.00 71.43 28.57 + 0 LEHB-01-077 6-Aug-01 39.35.75 74 14.07 5.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-078 6-Aug-01 3936.00 74 13.75 4.0 0.01 57.0 0.00 0.00 0.00 100.00: 0.00 4- 0 LEHB-01-079 6-Aug-01 39 36.25 74 13.43 5.0 0.05 49.5 0.00 0.00 100.00 0.00 0.00 + 0 LEHB-01-080 6-Aug-01 3936,538 74 12.575 6.0 0.03 61.5 0.00 0.00 50.00 50.00 0.00 + 0 LEHB-01-081 6-Aug-01 39 37.017 74 12.110 5.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-082 6-Aug-01 39 38.00 74 11.51 4.0 0.07 66.0 25.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-083 6-Aug-01 3938.25 74 11.34 4.0 . 0.02 72.0 0.00 0.00 0.00 100.00 0.00 Ruppia only 0 LEHB-01-084 7-Aug-01 39 37.25 74 12.05 5.0 0.27 64.5 0.00 0.00 8.33 91.67 0.00 + 0 LEHB-01-085 .7-Aug-01 39 35.757 74 13.146 12.0 0.00 .n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-086 7-Aug-01 3936.25 74 15.35 9.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-087 7-Aug-01
- 39 35.25 . 74 15.35 6.0 0.23 89.4 33.33 " 0.00 0.00 0.00 100.00 + 0 LEHB-01-088 7-Aug-01 39 35.00 74 15.67 7.0 0.30 85.2 13.33 0.00 0.00 23.08 76.92 + 0 LEHB-01-089 7-Aug-01 39 34.758 74 15.219 < 3.0 0.05 69.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-090 7-Aug-01 39 35.00 74 15.03 5.0 0.02 72.0 16.67 0.00 0.00 50.00 50.00 + 0 LEHB-01-091 7-Aug-01 3935.25 74 14.71 6.0 0.11 93.0 58.33 0.00 0.00 0.00 100.00 + 0 LEHB-01-092 7-Au1-01 39 34.75 74 14.71
- 6.0 0.07 74.0. 25.00 0.00 0.00 66.67 33.33 + 0 LEHB-01-093 7-Aug-01 39 34.50 74 14.39 5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-094 7-Aug-01 39 34.77 74 13.87 7.0 0.05 103.5 71.43 0.00 0.00 0.00 100.00 0 0 LEHB-01-095 8-Aug-01 3935.75 74 15.35 7.0 0.11 93.0 37.50 0.00 0.00 .0.00 100.00 0 0 LEHB-01-096 8-Aug-01 39 36.00 74 15.67 8.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 .0 LEHB-01-097 8-Aug-01 39 35.50 74 15.67 8.0 0.14 87.0 21.43 0.00 0.00 0.00 100.00 0 0 LEHB-01-098 8-Aug-01 39 34.50 74 17.61 7.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-099 8-Aug-01 3934.25 74 17.29 6.0 0.06 93.6 28.57 0.00 0-00 0.00 100.00 0 0 LEHB-01-100 8-Aug-01 3934.25 74 17.94 6.0 0.10 94.3 75.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-101 8-Aug-01 39 34.25 74 18.58 6.0 0.23 87.0 50.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-102 8-Aug-01 39 33,80 74 18.60 4.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 .0 0 LEHB-01-103 8-Aug-01 39 34.00 74 18.90 6.0 0.20 87.3 28.00 0.00 0.00 5.56 94.44 0 0 LEHB-01-104 8-Aug-01 39 33.999 74 17.670 < 3.0
- 0.14 . 99.5 53.85 0.00 0.00 0.00 100.00 0 0 LEHB-01-105. 8-Aug-01 39 34.25 74 16.65 7.0 0.45 86.9 20.00 0.00 2.50 2.50 95.00 + 0
of submerged aquatic vegetation Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Mean Length Percent Percent Percent Percent Percent SAV Mytilus Station Date Latitude Longitude Depth Abundance .j**
2 (clams/foot ) (m.m) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?
(feet) 0.01 99.0 83.34 0.00 0.00 0.00 100.00 0 0 LEHB-01-034 7-Aug-01 39 37.00 74 15.03 6.0 0.05 90.0 83.33 0.00 0.00 0.00 100.00 0 0 LEHB-01-035 17-Jul-01 3936.75 7415.35 6.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-036 17-Jul-01 39 37.00 74 15.67 5.0 0.02 84.0 75.00 0.00 0.00 0.00 100.00 + 0 LEHB-01-037 17-Jul-01 3937.25 74 15.35 5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-038 17-Jul-01 39 37.25 74 15.03 8.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-039 17-Jul-01 39 37.730 74 15,266 4.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-040 17-Jul-01 3938.25 7414.71 5.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-041 17-Jul-01 3938.25 74 14.07 3.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-042 17-Jul-01 39 38.50 74 14.39 6.0 0.03 85.0 81.25 0.00 0.00 0.00 100.00 0 0 LEHB-01-043 17-Jul-01* 39 38.50 74 13.75 5.0 0.25 73.6 0.00 0.00 0.00 72.73 27.27 0 0 LEHB-01-044 17-Jul-01 3938.50 74 13.11 9.0 0.02 56.0 66.67 0.00 0.00 100.00 0.00 + 0 LEHB-01-045 2-Aug-01 39 38.25 74 12.15 4.0 0.03 70.5 66.67 0.00 0.00 100.00 0.00 + 0 LEHB-01-046 2-Aug-01 39 38.00 74 12.00 4.0 0.07 61.0 0.00 0.00 33.33 66.67 0.00 + 0 LEHB-01-047 2-Aug-01 3938.00 74 12.47 4.0 0.05 66.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-048 2-Aug-01 39 37.75 74 12.79 4.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-049 2-Aug-01 3937.50 74 13.11 5.0 0.11 72.6 44.44 0.00 0.00 60.00 40.00 + 0 LEHB-01-050 2-Aug-01 3937.25 7413.43 5,0 0.02 84.0 33.33 0.00 33.33 66.67 0.00 + 0 LEHB-01-051 2-Aug-01 39 37.00 74 13.75 6,0 0.07 70.0 40.00 0.00 33.33 33.33 33.33 + 0 LEHB-01-052 2-Aug-01 39 37.50 74 12.47 5.0 0.05 72.8 71.43 0.00 0.00 75.00 25.00 0 a LEHB-01-053 2-Aug-01 39 37.50 74 12.15 4,0 0.39 65.8 5.56 0.00 11.76 88.24 0.00 + 0 LEHB-01-054 2-Aug-01 3937.75 74 12.15 4.0 0.02 75.0 50.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-055 2-Aug-01 39 37.85 74 11.80 4.0 0.02 63.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-056 3-Aug-01 39 37.75 74 13.43 4.0 0.11 42.0 50.00 0.00 0.00 60.00 40.00 + 0 LEHB-01-057 3-Aug-01 39 37.25 74 12.79 5.0 0.05 76.5 50.00 0.00 0.00 50.00 50.00 + 0 LEHB-01-058 3-Aug-01 3937,00 7413.11 5.0 0.06 53.4 0.00 0.00 80.00 20.00 0.00 + 0 LEHB-01-059 3-Aug-01 39 36.75 74 13.43 5.0 0.16 77.6 12.50 0.00 14.29 14.29 71.43 + 0 LEHB-01-060 3-Aug-01 3936.50 7413.11 6.0 0.10 72.4 29.17 0.00 0.00 62.50 37.50 + 0 LEHB-01-061 3-Aug-01 39 36.25 74 14,07 4.0 0.01 90.0 0.00 0.00 0.00 0.00 100.00 + .0 LEHB-01-062 3-Aug-01* 39 36.25 74 14.71 4.0 0.06 89.3 55.00 0.00 0.00 0.00 100.00 + 0 LEHB-01-063 7-Aug-01 39 36.00 74 15.03 6.0 0.20 70.3 10.00 0.00 0.00 100.00 0.00 0 0 LEHB-01-064 6-Aug-01 39 37.70 74 11.80 18.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-065 6-Aug-01 .39 37.00 74 12.40 4.0 0.07 57.0 40.00 0.00 33.33 66.67 0.00 + 0 LEHB-01-066 6-Aug-01 39 36.75
- 74.12.79 4.0 0,07 77.0 50.00 0.00 0.00 66.67 33.33 + 0 LEHB-01-067 6-Aug-01 39 36.00 74 13.11 4.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + . 0 LEHB-01-068 6-Au -01 39 35.75 74 13.43 4.0 0,00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-069 6-Aug-01 39 35:50 74 13.75 10.0
Table 4. Station locations, hard clam abundances, percent mortalities, commercial size class percentages and presence/absence of submerged aquatic vegetation (SAV) for the 2001 hard clam stock assessment of Little Egg Harbor Bay.
Station Date Latitude Longitude Depth Abundance dj** Mean Length Percent Percent Percent Percent Percent SAV' Mytilus (feet) (clams/foot) (ram) Mortality Sublegals Littlenecks Cherrystones Chowders present? present?
LEHB-01-001 16-Jul-01 39 39.75 74 12.79 .5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-002 16-Jul-01 39 39.50-" 74 12.79 6.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-003 16-Jul-01 3939.25 74 12.79 5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-004 16-Jul-01 39 39.00 74 12.79 5.0 0.02 63.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-005 2-Aug-01 39 39.25 74 12.15 4.0 0.05 36.0 50.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-OOSA 16-Jul-01 3939.713 74 12.518 6.0 0.02 69.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-006B 2-Aug-01 3939.70 74 12.47 11.0 0.02 66.0 0.00 0.00 0.00 100.00 0.00 0 0 LEHB-01-007 16-Jul-01 39 39.50 74 12.47 4.0 0.02 69.0 0.00 0.00 0.00 100.00 0.00 0 0 LEHB-01-008 16-Jul-01 3939.00 74 12.47 5.0 0.02 66.0 0.00 0.00 0.00 100.00 0.00 0 0 LEHB-01-009 2-Aug-01 3938.75 74 12.15 4.0 0.08 55.5 0.00 0.00 50.00 50.00 0.00 + 0 LEHB-01-010 2-Aug-01 3938.75 74 11.51 3.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-0111 16-Jul-01 3938.976 74 11.405 13.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-011.5 2-Aug-01 3939.05 74 11.30 14.0 0.18 64.1 11.11 0.00 25.00 62.50 12.50 0 0 LEHB-01-012 16-Jul-01 3939.286 74 11.429 13.0 0.43 62.4 0.00 0.00 15.79 78.95 5.26 0 0 LEHB-01-012.5 2-Aug-01 3939.25 74 11.35 4.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 Ruppia only 0 LEHB-01-013 16-Jul-01 3939.00 74 11.19 18.0 0.75 70.9 10.81 0.00 3.03 66.67 30.30 0 0 LEHB-01-014 16-Jul-01 3938.501 74 11.242 9.0 0.05 73.5 0.00 0.00 0.00 50.00 50.00 0 0 LEHB-01-015 2-Aug-01 3938.50 74 11.83 3.0 0.11 60.6 .44.44 0.00 20.00 80.00 0.00 + 0 LEHB-01-016 2-Aug-01 3938.50 74 12.47 5.0 0.07 73.0 0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-017 17-Jul-01 3938.75 74 14.07 6.0 0.00 n/a 100.00 0.00 0.00 .0.00 0.00 0 0 LEHB-01-018 17-Jul-01* 39 38.25 7413.43 5.0 0.08 64.3 25.00 0.00 42.86 42.86 14.29 + 0 LEHB-01-019 3-Aug-01 3938.100 74 12.966 3.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 - + 0 LEHB-01-020 17-Jul-01 3938.00 74 13.75 5.0 0.02 51.0 0.00 0.00 100.00 0.00 0.00 + 0 LEHB-01-021 17-Jul-01 3937.50 74 13.75 6.0 0.05 88.5 33.33 0.00 0.00 0.00 100.00 + 0 LEHB-01-022 17-Jul-01 3937.75 74 14.07 5.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-023 17-Jul-01 39 38.00 74 14.39 5.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 0 0 LEHB-01-024 3-Aug-01 3937.50 74 14.39 4.0 0.02 79.5 50.00 0.00 0.00 50.00. 50.00 + 0 LEHB-01-025 17-Jul-01 39 37.75 74 14.71 5.0 0.00 n/a 100.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-026 17-Jul-01 39 37.25 74 14.71 5.0 0.05 78.0 71.43 0.00 0.00 50.00 50.00 + 0 LEHB-01-027 17-Jul-01 3936.75 74 14.71 6.0 0.07 77.0 50.00 0.00 0.00 66.67 33.33 0 0 LEHB-01-028 17-Jul-01 3936.50 74 15.03 6.0 0.00 n/a 0.00 0.00 0.00 0.00 0.00 + 0 LEHB-01-029 17-Jul-01 39 37.00 74 14.39 6.0 0.09 84.0 20.00 0.00 0.00 0.00 100.00 0 0 LEHB-01-030 17-Jul-01 3937.25 74 14.07 5.0 0.11 82.8 28.57 0.00 . 0.00 20.00 80.00 + 0 LEHB-01-031 17-Jul-01 3936.75 74 14.07 5.0 0.07 71.0 .0.00 0.00 0.00 100.00 0.00 + 0 LEHB-01-032 17-Jul-01 39 36.50 74 13.75 4.0 0.09 96.8 55.56 0.00 0.00 100.00 0.00 + 0 LEHB-01-033 17-Jul-01 3936.50 74 14.39 5.0 0.18 70.9 38.46 0.00 12.50 50.00 37.50 + 0
Table 6. 2001 Little Egg Harbor Bay hard clam stock estimates, means, standard deviations and standard errors by commercial size class.
LITTLE EGG HARBOR BAY COMMERCIAL SIZE CLASS ABUNDANCES Sublegals Littlenecks Cherrystones Chowders Clams 1,088,308 6,130,523 14,614,435 42,970,475 Mean* 13,272 74,762 178,225 524,030 St. Dev. 55,942 223,890 .335,509 1,520,252 SL Error 6,178 24,724 37,051 167,884 Percent of 1 Total 1.7% 9.5% 22.6% 66.3%
Mean is the average of all values used ingrand sum of clams.
Sublegals: 30-37 mm; Littlenecks: 38-55 mm; Cherrystones: 56-76 mm; Chowders: >76 mm.
Difference in estimates between this table and text on page 9 of report are due to rounding and averaging.
Table 7. Comparison of the number and percent of stations sampled in 1986/87 and 2001 with no hard clams, low, moderate and high abundances of hard clams.
Bay Year Percent of stations Percent of stations Percent of stations Percent of stations with no clams with low abundances with moderate abundances with high abundances of hard clams of hard clams of hard clams Little Egg Harbor Bay 1986/87 3.2 50.3 29.6 16.9 1 Little Egg Harbor Bay 2001 35.1 51.0 11.9 2.1 Low abundance: 0.01-.019 clams foot:2; moderate abundance: 0.20-0,49 clams foot'2; high abundance: > 0.50 clams foot=2 .
Table 10. Comparison of 1986/87 and 2001 recruitment and mortality indices for Little Egg Harbor Bay.
Little Egg Harbor Bay 2001 Statistic Recruitment (%) Mortality (%)
Average 1.2 39.7 Minimum 0.0 0.0 Maximum 12.1 100.0 Standard Deviation 3.1 39.0 Count (n) 27 194 Little Egg Harbor Bay 1986187 Statistic Recruitment (%) Mortality (%
Average 3.9 11.6 Minimum 0.0 0.0 Maximum 34.6 100.0 Standard Deviation 5.3 13.8 Count (n) 88 189
Table 12. Average, minimum and maximum abundance of species collected during the 2001 hard clam inventory of Little Egg Harbor Bay.
Abundance*
Species Average Minimum Maximum SD No. of "+"
Aeguipecten irradians N/A *** 0.00 0.00 N/A 0 Anadara ovalis 0.07 0.01 0.42 0.07 0 Arbaciapunctulata N/A 0.00 0.00 N/A 0 Asterias forbesi 0.02 0.02 0.02 0.02 0 Busycon canca 0.02 0.01 0.07 0.02 0 Busycotypus canaliculatus 0.01 0.01 0.01 0.01 0 Callinectes sapidus 0.02 0.01 0.04 0.02 0 Cancerborealis N/A 0.00 0.00 N/A 0 Cancerirroratus 0.30 0.02 1.04 0.30 0 Crepidulaspp. 0.04 0U04 0.04 0.04 11 Ensis directus 0.08 0.01 0.50 0.08 0 Eupleura caudata N/A 0.00 0.00 N/A 0 llyanassa obsoletus N/A 0.00 0.00 N/A 2 Libinia dubia 0.03 0.03 0.03 0.03 0 Libinia emarginata 0.09 0.01 0.50 0.09 0 Libinia spp. 0.07 0.03 0.10 0.07 0 Limulus polyphemus 0.01 0.01 0.01 0.01 0 Littorina littorea N/A 0.00 0.00 N/A 0 Lunatia heros N/A 0.00 0.00 N/A 0 Mulinia lateralis N/A 0.00 0.00 N/A 0 Mya arenaria N/A 0.00 0.00 N/A 0 Mytilus edulis 18.03 0.02 162.24 18.03 0 Nassarius trivittatus N/A 0.00 0.00 N/A 0 Noetia ponderosa 0.03 0.02 0.04 0.03 0 Ovalipes ocellatus 0.04 0.01 0.10 0.04 0 Pagurusspp. 0.02 0.02 0.02 0.02 8 Petricolapholadiformis. N/A 0.00 0.00 N/A 0 Pitarmorrhuana 0.04 0.01 0.06 0.04 0 Polinicesduplicatus 0.04 0.01 0.10 0.04 0 Retusa spp. 0.01 0.01 0.01 0.01 0 Sclerodactyla briareus 0.03 0.02 0.03 0.03 0 Solemya velum 0.02 0.02 0.03 0.02 26 SNisula sotidissima blN/A 0.00 0.00 NdA 0 Squilla empusa 0.02 0.01 0.03 0.02 0 Tagelus spp. 0.02 0.02 0.03 0.02 4 Telfina spp. N/A 0.00 0.00 N/A 2 Urosalpinx Cinerea 0.03 0.03 0.03 0.03 0
,Xanthidae (Family) 0.03 0.02 0.03 0.03 135
- Abundance = number collected per square foot.
- SD = Standard Deviation.
- += Number of stations where species was present (no quantitative description).
- N/A = Not Available (due to division by 0).
Figure 1. Location of the 2001 shellfish inventory sampling area (Little Egg Harbor Bay, Ocean County, New Jersey).
244 Want creek *.; a1 58 61 WLOh 123N N
57 14 88 S
0 1uMestes LEGEND Aquaculture Lease Areas
Figure 4. 1986187 Little Egg Harbor Bay Shellfish Inventory: SAV distribution.
1 0 1 Miles
Figure 5. 2001 Little Egg Harbor Bay Shellfish Inventory: SAV distribution.
1 0 1 Miles
Figure 6. 2001 Little Egg Harbor Bay sneAntisn inventory: starnon locations.
1 0 1 Miles p.=. -=!!!!-n 29
Figure 7. 1986/87 Little Egg Harbor Bay Shellfish Inventory:
distribution and abundance of the hard clam, Mercenaria mercenaria.
30
Figure 8. 2001 Little Egg Harbor Bay Shellfish Inventory: distribution and abundance of the hard clam, Mercenaria mercenaria.
47 33 44 4?
" "
55 t Marsh Mas :31 IL so
,'*T . .. .... *: 4
~ ~
" :. .i i :".:: * .?.. ....
- i:-:.i ..: !:* :~.*::*.: -.....~ ~ *~...
. . .:Ao*..
- ... ..92.*.,... 53i:i:i!::*:
. ...
,,',,,,,,0 * .. ..: .: i . .*i....::i:!i:.:.! ;::, ..: , 4 2* '57 50.
.. ~~~~~ :.:!<** .. _:...:*..*
- 344 0 S3
.. :,*.::*:
C* " :....* so
_ ..~*~ ... O*: ~ ~ ~i:i".ii ~... .,5.3** ~ .:..* ~ :*:...~ ~ 4 * .
- ~~~~ -::O-
~~~~~~~~~1 .--2.......TOM : . *......< ,]* 27 '44 52*..
.....
ot ... ***-*.::..-
crAquaculture .**.. 371 " Lease Area"s:
- ,.*..* ... 1t" HARD CLAM ABUNDANCES
...
. ... . *.. Mile201 . 42 1
- ..:: ;, :"..°*'._.:...
j:: . ' V* .-::::! -* "::.:":,.] ::.* " : :-
Mash .ND . .... . ......
'. :t ::i::"::.'*i:.:i::::.. !i]]i:.i: 15-::: .. <= " i h c:= C *:
-... 22 ..........
- ~~~1 .... .;::<:::, 47 ,, Lease Areas.,L 10 1 Miles*
Figure 9. 1986/87 Little Egg Harbor Bay Shellfish Inventory: composite length-percent-frequency distribution graph.
12%
n =7,113 x 74.6 mm SD = 11.0 mm
_
10%
8%
C 4%
2%
0%
0 20 40 60 80 100 120 140
.Shell Length (mm)
Figure 10. 2001 Little Egg Harbor Bay Shellfish Inventory: composite length-percent-frequency distribution graph.
12%
n=939 x=78.9mm SD = 15.3 mm 10%
8%
C 6%
LL 4%
2%
0%
0 20 40 60 80 100 120 140 Shell Length (mm)
g*U1Z 1 9. RIO VIU :V.DLI§% ffintsi a. %0%0 *11"1l a-%A saa -
recruitment indices (%) at stations with moderate and high abundances of hard clams.
1 0 1 Miles 34
H-qgure IZ. ZUI LDU*Je tgg maroor nay znen1iTsn inventory; rvurunuvwivD indices (%) at stations with moderate and high abundances of hard clams.
35
Figure 13a. 1986187 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%) at all stations (northern Little Egg Harbor Bay).
1 0 1 Miles
Figure 13b. 1986/87 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%) at all stations (southern Little Egg Harbor Bay).
1 0 1 Miles
Figure 14a. 2001 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%) at all stations (northern Little Egg Harbor Bay).
1 1 Miles 1 0 1 Miles
Figure 14b. 2001 Little Egg Harbor Bay Shellfish Inventory: mortality indices (%) at all stations (southern Little Egg Harbor Bay).
1 1 .0 1 0 1 Miles
Figure 15. 2001 Little Egg Harbor Bay Shellfish Inventory: distribution of blue mussels, Mytilus edulis.
^!
.,5 N... ......
.. ... o ifuc "4. r
- 5 TAN N. . :
37 -4... 57Y WeaCreek Rid B 4
-. ~ ~ ~ A 42- 51i::::...:5
"~>* h r2324) 2 5
. .:.. .... :*;:J
- "::.. "::.::" :.**.: :" ::"" * *'":':" : :i~~i: ' 8se i**.e i~ ~ ~ ~ ~ 2 35::*~ o** :.
.. : ... : ':"
- .:i
' " *..':*;*:;
"' ..*"....". i . " .... :." "2
- i~~i4. * .t 34;
.. . :-... -- e..
S3.
=:*IOX .".
- 8
.... .. . S
- " " . " " .. _ 4. . . .. I - -- . . . . ...
1moll 0- -- *--
1 Miles
Figure 16. 1986187 Little Egg Harbor Bay Shellfish Inventory: distribution of blue mussels, Mytilus edulis.
N~
/2 W 484
'7
.... s * .....-- ....
" "44,
. "... 51< .
---
, ,o*_*., 5
"- ~ ~~~~ == 0 1WEM1les A'af 92=ee
- S s.o."
50 t "i..." ". .. . . .. .. .
.. :.,!. . .=* =t* * "" * *23
- '.*,. .,. * . ... .: * *,*"T* '*. : ./ '-' :.. " ':* 3
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MUTLICA RIVER OYS1I'M *L2 ili r 1974 - 1986 BED FRENCHES POINT BED MOSS POINT EAR CONDITION OYSTER AGE COMPOSITION OF POIULATION SPAT W"
- YEARLINGý OLDER
- SPAT PA EONT OYSTERS
'
ANNUAL MORTALI 4 BED CONDITION OYSTER 7 PAT AGE COMPOSITION OF POPULATION YERING %
YEA OLDER OYSTER OYTR
- SPAT
/DuSI
//UTI '*
KWTNJAL
-ORTALIT ND ND 30.6 25.8 43.6 ND 974 ND 15.8 I6o.1 ND 5-6 6.4 79.3 3.2 28.1 68.7 53 80..9 5.2 25.6 69.2 77 975 91.8 0.3 2.1 97.6 3 5.9 0.2 3.2 96.6 2 10.4 976 85.9 78.7 12-3 3.1 84.6 132 lh .4 6.0 0.9 93.1 46 24.0 977 67.7 8.8 76.5 80 6.2 1.0 4.1 94.9 5 13.7 84.7 14.7 978 65.3 84.2 65.7 0.6 33.7 1635 62.5 0.8 36.7 1066 4.9 979 81.1 91.2 1.0 42.1 56.9 31 3.0 43.9 53.1 5.8 980 81.0 87.4 30.5 6.3 63.2 384 14.0 26.9 1145 10.2 981 56.8 59.1 914.7 13.3 17.7 68.9 178 19.8 71.7 80 11i7 982 73.8 8.5 51.9 11.3 78.2 13.0 68.4 245 983 81.4 28.9 5.1 66.0 394 1.7 86.0 21 21 1.7 85.3 12.3 94-.8 1 .7 7.3 91.0 984 59.7 3.0 37.3 67 51 34.6 39 .3 0.7 60.0 235 36.6 65.8 985 65.5
- 3 . 74 62.1 45.2 21.2 54.0 24.8 262ý 2 6_5 986 IO'4 33 30.8 35.9 1i ND - No Data Available
- 37 qt./bushel Source: Nacote Creek Shellfish Office Records