ANNUALPROGRESS REPORT Data collection and analysis in support of single and multispecies stock assessments in Chesapeake Bay: The Chesapeake Bay Multispecies Monitoring and Assessment Program School of Marine Science College of William and Mary Virginia Institute of Marine Science Gloucester Point, VA 23062
Christopher F. Bonzek Robert J. Latour, Ph.D James Gartland
June 2007
ANNUAL PROGRESS REPORT
Data collection and analysis in support of single and multispecies stock assessments in Chesapeake Bay: The Chesapeake Bay Multispecies Monitoring and Assessment Program
U.S. Fish and Wildlife Service Sportfish Restoration Project F-130-R-2 April 2006 – March 2007
Submitted June 2007
Prepared by: Christopher F. Bonzek Robert J. Latour, Ph.D James Gartland
School of Marine Science College of William and Mary Virginia Institute of Marine Science Gloucester Point, VA 23062
Submitted to: Virginia Marine Resources Commission United States Fish and Wildlife Service
ChesMMAP Staff: Principal Investigators:
Robert J. Latour, Ph.D. Christopher F. Bonzek
Project Manager:
James Gartland
Field and Laboratory Staff: Eric Brasseur Melanie Chattin RaeMarie Johnson Graduate Students:
Andre Buchheister Andrij Horodysky Patrick Lynch Kathleen McNamee
Introduction Historically, fisheries management has been based on the results of single-species stock assessment models that focus on the interplay between exploitation level and sustainability. There currently exists a suite of standard and accepted analytical frameworks (e.g., virtual population analysis (VPA), biomass dynamic production modeling, delay difference models, etc.) for assessing the stocks, projecting future stock size, evaluating recovery schedules and rebuilding strategies for overfished stocks, setting allowable catches, and estimating fishing mortality or exploitation rates. A variety of methods also exist to integrate the biological system and the fisheries resource system, thereby enabling the evaluation of alternative management strategies on stock status and fishery performance. These well-established approaches have specific data requirements involving biological (life history), fisheries-dependent, and fisheries-independent data (Table 1). From these, there are two classes of stock assessment or modeling approaches used in fisheries: partial assessment based solely on understanding the biology of a species, and full analytical assessment including both biological and fisheries data. Table 1. Summary of biological, fisheries-dependent and fisheries-independent data requirements for single-species analytical stock assessment models. Data Category Biological / Life History
Assessment Type Partial
Fishery-Dependent Data
Analytical
Fishery-Independent Data
Analytical
Data Description Growth (length / weight) Maturity schedule Fecundity Partial recruitment schedules Longevity Life history strategies (reproductive and behavioral) Catch, landings, and effort Biological characterization of the harvest (size, sex, age) Gear selectivity Discards/bycatch Biological characterization of the population (size, sex, age) Mortality rates Estimates of annual juvenile recruitment
Although single-species assessment models are valuable and informative, a primary shortcoming is that they generally fail to consider the ecology of the species under management (e.g., habitat requirements, response to environmental change), ecological interactions (e.g., predation, competition), and technical interactions (e.g.,
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discards, bycatch) (NMFS 1999, Link 2002a,b). However, inclusion of ecological processes into fisheries management plans is now strongly recommended (NMFS 1999, NRC 1999, Pew Commission 2003, U.S. Oceans Commission 2004) and in some cases even mandated (NOAA 1996). Multispecies assessment models have been developed to move towards an ecosystem-based approach to fisheries management (Hollowed et al. 2000, Whipple et al. 2000, Link 2002a,b). Although such models are still designed to yield information about sustainability, they are structured to do so by explicitly incorporating the effects of ecological processes among interacting populations. Over the past several years, the number and type of multispecies models designed to provide insight about fisheries questions has grown significantly (Hollowed et al. 2000, Whipple et al. 2000). This growth has been fueled by the need to better inform fisheries policy makers and managers, however, recent concerns about effects of fishing on the structure of ecosystems have also prompted research activities on multispecies modeling and the predator-prey relationships that are implied. From a theoretical perspective, basing fisheries stock assessments on multispecies rather than singlespecies models certainly appears to be more appropriate, since multispecies approaches allow a greater number of the processes that govern population abundance to be modeled explicitly. However, this increase in realism leads to an increased number of model parameters, which in turn, creates the need for additional types of data. In the Chesapeake Bay region, there has been a growing interest in ecosystem-based fisheries management, as evidenced by the recent development of fisheries steering groups (e.g., ASMFC multispecies committee), the convening of technical workshops (Miller et al. 1996; Houde et al. 1998), publication of the Fisheries Ecosystem Planning document (Chesapeake Bay Fisheries Ecosystem Advisory Panel 2006), and the goals for ecosystem-based fisheries management set by the Chesapeake Bay 2000 (C2K) Agreement. In many respects, it can be argued that the ecosystem-based fisheries mandates inherent to the C2K Agreement constitute the driving force behind this growing awareness. The exact language of the C2K agreement, as it pertains to multispecies fisheries management, reads as follows: 1. By 2004, assess the effects of different population levels of filter feeders such as menhaden, oysters and clams on Bay water quality and habitat. 2. By 2005, develop ecosystem-based multispecies management plans for targeted species. 3. By 2007, revise and implement existing fisheries management plans to incorporate ecological, social and economic considerations, multispecies fisheries management and ecosystem approaches. If either single-species or ecosystem-based management plans are to be developed, they must be based on sound stock assessments. In the Chesapeake Bay region,
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however, the data needed to perform single and multispecies assessments is either partially available or nonexistent. The Chesapeake Bay Multispecies Monitoring and Assessment Program (ChesMMAP) was developed to assist in filling these data gaps, and ultimately to support bay-specific stock assessment modeling activities at both single and multispecies scales. While no single gear or monitoring program can collect all of the data necessary for both types of assessments, ChesMMAP was designed to maximize the biological and ecological data collected for several recreationally, commercially, and ecologically important species in the bay. In general, ChesMMAP is a large-mesh bottom trawl survey designed to sample late juvenile-to-adult fishes in Chesapeake Bay. This field program currently provides data on relative abundance, length, weight, age, and trophic interactions for several important fish species seasonally inhabiting the bay. This report summarizes the field, laboratory, and preliminary data. Among the research agencies in the Chesapeake Bay region, only VIMS has a program focused on multispecies issues involving the adult/harvested components of the exploited fish species that seasonally inhabit the bay. The multispecies research program at VIMS is comprised of three main branches: field data collection (ChesMMAP and the VIMS Seagrass Trammel Net Survey), laboratory processing (The Chesapeake Trophic Interactions Laboratory Services – CTILS, and ChesMMAP), and data analysis and multispecies modeling (The Fisheries Ecosystem Modeling and Assessment Program - FEMAP). In this report, we summarize the field, laboratory, and data analysis activities associated with the 2006 sampling year. The following Jobs are addressed in this report: • Job 1 – Conduct research cruises • Job 2 – Synthesize data for single species analyses • Job 3 – Quantify trophic interactions for multispecies analyses • Job 4 – Estimate abundance Methods Job 1 – Conduct research cruises In 2006, five research cruises were conducted bimonthly from March to November in the mainstem of Chesapeake Bay. The timing of the cruises was chosen to adequately characterize the seasonal abundances of fishes in the bay. The R/V Bay Eagle, a 19.8m aluminum hull, twin diesel vessel owned and operated by VIMS, served as the sampling platform for this survey. The trawl net is a 13.7m (headrope length) 4-seam balloon trawl manufactured by Reidar’s Manufacturing Inc. of New Bedford, MA. The wings and body of the net are constructed of #21 cotton twine (15.2cm mesh), and the codend is constructed of #48 twine (7.6cm mesh). The legs of the net are 6.1m and connected directly to 1.3m x 0.8m steel-V trawl doors weighing 83.9kg each. The trawl
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net is deployed with a single-warp system using 9.5mm steel cable with a 37.6m bridle constructed of 7.9mm cable. For each cruise, the goal was to sample 80 stations distributed in a stratified random design throughout the mainstem of Chesapeake Bay. The Bay was stratified by dividing the mainstem into five regions of 30 latitudinal minutes each (the upper and lower regions being slightly smaller and larger than 30 minutes, respectively). Within each region, three depth strata ranging from 3.0m-9.1m, 9.1m-15.2m, and >15.2m were defined. A grid of 1.9km2 cells was superimposed over the mainstem, where each cell represented a potential sampling location. The number of stations sampled in each region and in each stratum was proportional to the surface area of water represented. Stations were sampled without replacement and those north of Pooles Island (latitude 39o 17’) have not been sampled since July 2002 due to repeated loss of gear. In the future, sidescan sonar will be used to identify potential sampling locations in this area. Tows were conducted in the same general direction as the tidal current (pilot tows conducted using the net monitoring gear in November 2001 indicated that the gear performed most consistently when deployed with the current rather than against the current). The net was generally deployed at a 4:1 scope, which refers to the amount of cable deployed relative to depth. For shallow stations, however, the bridle was always deployed beyond the vessel’s tow-point, implying that the scope ratio could be quite high. The target tow speed was 6.5 km/h but occasionally varied depending on wind and tidal conditions. Based on data collected from the net monitoring gear, tow speed and scope were also adjusted occasionally to ensure that the gear was deployed properly. Tows were 20 minutes in duration, unless obstructions or other logistical issues forced a tow to be shortened (if the duration of a tow was at least 10 minutes, it was considered complete). Computer software was used to record data from the net monitoring gear (i.e., wingspread and headrope height) as well as a continuous GPS stream during each tow. On occasions when the monitoring gear failed, the trawl geometry was assumed to follow cruise averages and beginning and ending coordinates were taken from the vessel’s GPS system.
Job 2 – Synthesize data for single species analyses Once onboard, the catch from each tow is sorted and measured by species or sizeclass if distinct classes within a particular species are evident. A subsample of each species or size-class is further processed for weight determination, stomach contents, ageing, and determination of sex and maturity stage. In addition, surface and bottom temperature, salinity, and dissolved oxygen readings are also recorded at each sampling location. Single-species assessment models typically require information on (among others) agelength-, and weight-structure, sex ratio, and maturity stage. Data were synthesized to characterize age-, length-, and weight-frequency distributions across a variety of spatial
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and temporal scales (e.g., by year, season, or region of the bay) for each species. Sex ratio and maturity data are also be available to support sex-specific analyses. Job 3 – Quantify trophic interactions for multispecies analyses In addition to the population-level information described under Task 3, multispecies assessment models require information on predator-prey interactions across broad seasonal and spatial scales. In general, these procedures involve identifying each prey item to the lowest possible taxonomic level (Hyslop 1980). Several diet indices were calculated to identify the main prey types for each species: %weight, %number, and %frequency-of-occurrence. These indices were coupled with the information generated from Task 3 and age-, length-, and sex-specific diet characterizations were developed for each species. Efforts also focused on characterizing spatial and temporal variability in these diets. Diet index values were calculated to identify the main prey in the diet of predators in the mainstem Chesapeake Bay. Since trawl collections essentially yield a cluster of fish at each sampling location, the aforementioned indices were calculated using a cluster sampling estimator (Buckel et al. 1999). The contribution of each prey type to the diet (%Qk, where Qk is any of the aforementioned index types) is given by: n
%Qk =
∑M q i =1 n
i ik
∑M i =1
,
(1)
i
where
qik =
wik * 100 , wi
and where n is the number of trawls containing the predator of interest, Mi is the number of that predator collected at sampling site i, wi is the total weight, number, or frequency of all prey items encountered in the stomachs of that predator collected from sampling location i, and wik is the total weight, number, or frequency of prey type k in those stomachs. Accordingly, stomachs collected in the field were processed following standard diet analysis procedures (Hyslop 1980).
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Job 4 – Estimate abundance Time-series of relative abundance information can easily be generated from the basic catch data of a monitoring survey. For each species, a variety of relative abundance trends can be generated according to year, season, and location within the Bay. Absolute abundance estimates can be generated for each species by combining relative abundance data with area swept and gear efficiency information. Area swept was calculated for each tow by multiplying tow distance (provided by GPS equipment) by average wingspread (provided by net monitoring gear). Gear efficiency estimates are being derived by comparing the number of fish that encounter the gear (from the hydroacoustic data) with the fraction captured (from the catch data). To develop species-specific efficiency estimates, the hydroacoustic data will be partitioned according to the target strength distribution for each species. These distributions will be determined through ongoing cage experiments. ChesMMAP utilizes two types of hydroacoustic gear in an effort to convert relative indices of abundance into estimates of total abundance. The equation necessary for this conversion is: cA N= , (1) a e where N is total population size measured in numbers (or biomass), c is the mean number (or weight) of fish captured per tow, a is the area swept by one trawl tow, A is the total survey area, and e is the net efficiency (dimensionless). Given that c is observed and A is easily determined, the hydroacoustic equipment is used to derive estimates of a and e. Estimation of the parameter e for a variety of species is a mid-tolong term goal. Until then, removal of that parameter from Equation 1 results in relative estimates of ‘minimum trawlable abundance.’ These estimates represent the smallest number (or biomass) of fish present within the sampling area that are susceptible to the sampling gear. Results Job 1 – Conduct Research Cruises Throughout the five years of sampling, the number of fish collected each year by the ChesMMAP survey was fairly consistent and ranged from approximately 31,000 (in 2003) to 48,000 (in 2004 – Table 1). Each year, between 3,900 and 6,000 pairs of otoliths have been collected, the majority of which have been processed for age determination. Similar numbers of stomach have been collected and processed for diet composition information annually.
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Table 1. The number of specimens collected, measured and processed for age determination and diet composition information from ChesMMAP 2002 – 2006. Year Fish Fish Otoliths Otoliths Stomachs Stomachs collected measured collected processed collected processed 2002 32,018 23,605 5,487 4,382 4,555 2,638 2003 30,925 20,828 3,913 2,934 3,250 2,220 2004 47,623 31,245 5,169 3,431 4,271 3,137 2005 45,206 36,906 6,064 4,694 5,064 3,170 2006 43,959 31,239 5,412 In process 4,391 2,640 Jobs 2-4 – Data Summaries The data summaries in this report essentially represent biological and ecological profiles of those species well sampled by the ChesMMAP survey. Our intent with these profiles is to maximize the amount of information available to fishery managers. The profiles that follow are organized first by species and then by type of analysis (‘Task’). Each Task element (single-species stock parameter summarizations, trophic interaction summaries, and estimates of abundance) is included but is not labeled with a Task number and is not necessarily shown in Task number order (note also that not all analysis types are available for all species). The species profiles contain the following information (note that some data/analyses may not be available for all species): 1) estimates of abundance, both in numbers and biomass, by year, month, and region within the bay 2) site-specific abundance maps (number per area swept) for each cruise, overlaid on depth strata 3) length-frequency data by year 4) age-class distributions by year (for those species where appreciable numbers have been captured and otoliths have been processed) 5) sex-ratio by year and where appropriate, by region, month, and/or by age. 6) statistically determined length-weight relationships for sexes combined and separately 7) sex-specific maturity ogives along with a single diet summary Following the species profiles figures are a series of figures for each cruise containing data describing the following water quality parameters: 1) Water temperature at the surface and at the bottom. 2) Salinity at the surface and at the bottom. 3) Dissolved oxygen at the surface and at the bottom.
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List of Figures Atlantic Croaker (pages 17 – 27) Figure 1. Atlantic croaker minimum trawlable abundance estimates in Chesapeake Bay, 2002-2006. Figures 2 – 6. Site-specific Atlantic croaker abundance figures, 2002-2006. Figure 7. Atlantic croaker length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 8. Atlantic croaker age-frequency distribution in Chesapeake Bay, 2002-2005 (2006 ages not yet assigned). Figure 9. Atlantic croaker sex-ratios in Chesapeake Bay, 2002-2006, by (A) region, and (B) age. Figure 10. Atlantic croaker length-weight relationships in Chesapeake Bay, 2002-2006 for (A) sexes combined, and (B) males and females separated. Figure 11. Atlantic croaker maturity schedule in Chesapeake Bay, 2002-2006 for sexes combined. Figure 12. Atlantic croaker diet composition in Chesapeake Bay, 2002-2006.
Black Seabass (pages 29 – 35) Figure 13. Black seabass minimum trawlable abundance estimates in Chesapeake Bay, 2002-2006. Figure 14. Black seabass length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 15. Black seabass age-frequency distribution in Chesapeake Bay, 2002-2003. Figure 16. Black seabass sex-ratios in Chesapeake Bay, 2002-2006, by (A) year and (B) month. Figure 17. Black seabass length-weight relationships in Chesapeake Bay, 2002-2006 for (A) sexes combined and (B) males and females separated. Figure 18. Black seabass maturity schedule for females in Chesapeake Bay, 20022006. Figure 19. Black seabass diet composition in Chesapeake Bay 2002-2006.
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Bluefish (pages 37 – 47) Figure 20. Bluefish minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 21 – 25. Site-specific bluefish abundance figures, 2002-2006. Figure 26. Bluefish length-frequency distribution in Chesapeake Bay 2002-2006. Figure 27. Bluefish age-frequency distribution in Chesapeake Bay, 2002-2004 (20052006 ages not yet assigned). Figure 28. Bluefish sex-ratios in Chesapeake Bay 2002-2006, by year. Figure 29. Bluefish length-weight relationships in Chesapeake Bay, 2002-2006 for (A) sexes combined and (B) males and females separated. Figure 30. Bluefish maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 31. Bluefish diet composition in Chesapeake Bay, 2002-2006.
Butterfish (pages 49 – 56) Figure 32. Butterfish minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 33 – 37. Site-specific butterfish abundance figures, 2002-2006. Figure 38. Butterfish length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 39. Butterfish length-weight relationship in Chesapeake Bay, 2002-2006. Figure 40. Butterfish diet composition in Chesapeake Bay, 2002-2006.
Northern Kingfish (pages 57 – 66) Figure 41. Northern kingfish minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 42 – 46. Site-specific northern kingfish abundance figures, 2002-2006. Figure 47. Northern kingfish length-frequency distribution in Chesapeake Bay 20022006. Figure 48. Northern kingfish sex-ratios in Chesapeake Bay, 2002-2006, by (A) year and (B) month.
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Figure 49. Northern kingfish length-weight relationships in Chesapeake Bay, 20022006, for (A) sexes combined and (B) males and females separated. Figure 50. Northern kingfish maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 51. Northern kingfish diet composition in Chesapeake Bay, 2002-2006.
Northern Puffer (pages 68 – 73) Figure 52. Northern puffer minimum trawlable abundance estimates in (A) numbers and (B) biomass (B) in Chesapeake Bay, 2002-2006. Figure 53. Northern puffer length-frequency distribution in Chesapeake Bay, 20022006. Figure 54. Northern puffer sex-ratios in Chesapeake Bay, 2002-2006, by (A) year and (B) month. Figure 55. Northern puffer length-weight relationships in Chesapeake Bay, 2002-2006, for (A) sexes combined and (B) males and females separated. Figure 56. Northern puffer maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 57. Northern puffer diet composition in Chesapeake Bay, 2002-2006.
Scup (pages 75 – 84) Figure 58. Scup minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 59 – 63. Site-specific scup abundance figures, 2002-2006. Figure 64. Scup length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 65. Scup sex-ratios in Chesapeake Bay, 2002-2006, by (A) year and (B) month. Figure 66. Scup length-weight relationships in Chesapeake Bay, 2002-2006, for (A) sexes combined and (B) males and females separated. Figure 67. Scup maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 68. Scup diet composition in Chesapeake Bay, 2002-2006.
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Spot (pages 85 – 95) Figure 69. Spot minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 70 – 74. Site-specific spot abundance figures, 2002-2006. Figure 75. Spot length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 76. Spot age-frequency distribution in Chesapeake Bay, 2002-2006. Figure 77. Spot sex-ratios in Chesapeake Bay, 2002-2005, by (A) year and (B) month. Figure 78. Spot length-weight relationships in Chesapeake Bay 2002-2006 for (A) sexes combined and (B) males and females separated. Figure 79. Spot maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined.
Striped Bass (pages 97 – 107) Figure 80. Striped bass minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 81 – 85. Site-specific striped bass abundance figures, 2002-2006. Figure 86. Striped bass length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 87. Striped bass age-frequency distribution in Chesapeake Bay. 2002-2006. Figure 88. Striped bass sex-ratios in Chesapeake Bay. 2002-2006, by (A) year, (B), month, and (C) age. Figure 89. Striped bass length-weight relationships in Chesapeake Bay, 2002-2006, for (A) sexes combined and (B) males and females separated. Figure 90. Striped bass maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 91. Striped bass diet composition in Chesapeake Bay, 2002-2006.
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Summer Flounder (pages 109 – 119) Figure 92. Summer flounder minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 93 – 97. Site-specific summer flounder abundance, 2002-2006. Figure 98. Summer flounder length-frequency distribution in Chesapeake Bay, 20022006. Figure 99. Summer flounder age-frequency distribution in Chesapeake Bay, 20022006. Figure 100. Summer flounder sex-ratios in Chesapeake Bay, 2002-2006, by (A) month, (B) region and (C) age. Figure 101. Summer flounder length-weight relationships in Chesapeake Bay, 20022005 for (A) sexes combined and (B) males and females separated. Figure 102. Summer flounder maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 103. Summer flounder diet composition in Chesapeake Bay 2002-2006.
Weakfish (pages 121 – 131) Figure 104. Weakfish minimum trawlable abundance estimates in (A) numbers and (B) biomass (B) in Chesapeake Bay, 2002-2006. Figures 105 – 109. Site-specific weakfish abundance, 2002-2006. Figure 110. Weakfish length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 111. Weakfish age-frequency distribution in Chesapeake Bay, 2002-2006. Figure 112. Weakfish sex-ratios in Chesapeake Bay, 2002-2005, by (A) year, (B) region and (C) age. Figure 113. Weakfish length-weight relationships in Chesapeake Bay, 2002-2006, for (A) sexes combined and (B) males and females separated. Figure 114. Weakfish maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 115. Weakfish diet composition in Chesapeake Bay, 2002-2006.
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White Perch (pages 133 – 143) Figure 116. White perch minimum trawlable abundance estimates in (A) numbers and (B) biomass in Chesapeake Bay, 2002-2006. Figures 117 – 121. Site-specific white perch abundance, 2002-2006. Figure 122. White perch length-frequency distribution in Chesapeake Bay, 2002-2006. Figure 123. White perch age-frequency distribution in Chesapeake Bay, 2002-2005. Figure 124. White perch sex-ratios in Chesapeake Bay 2002-2005, by (A) year and (B) age. Figure 125. White perch length-weight relationships in Chesapeake Bay, 2002-2006 for (A) sexes combined and (B) males and females separated. Figure 126. White perch maturity schedule in Chesapeake Bay, 2002-2006, for sexes combined. Figure 127. White perch diet composition in Chesapeake Bay, 2002-2006. Water Temperature (pages 144 – 153) Figure 128. Surface temperature in Chesapeake Bay, 2002. Figure 129. Bottom temperature in Chesapeake Bay, 2002. Figure 130. Surface temperature in Chesapeake Bay, 2003. Figure 131. Bottom temperature in Chesapeake Bay, 2003. Figure 132. Surface temperature in Chesapeake Bay, 2004. Figure 133. Bottom temperature in Chesapeake Bay, 2004. Figure 134. Surface temperature in Chesapeake Bay, 2005. Figure 135. Bottom temperature in Chesapeake Bay, 2005. Figure 136. Surface temperature in Chesapeake Bay, 2006. Figure 137. Bottom temperature in Chesapeake Bay, 2006.
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Salinity (pages 154 – 163) Figure 138. Surface salinity in Chesapeake Bay, 2002. Figure 139. Bottom salinity in Chesapeake Bay, 2002. Figure 140. Surface salinity in Chesapeake Bay, 2003. Figure 141. Bottom salinity in Chesapeake Bay, 2003. Figure 142. Surface salinity in Chesapeake Bay, 2004. Figure 143. Bottom salinity in Chesapeake Bay, 2004.
Figure 144. Surface salinity in Chesapeake Bay, 2005. Figure 145. Bottom salinity in Chesapeake Bay, 2005. Figure 146. Surface salinity in Chesapeake Bay, 2006. Figure 147. Bottom salinity in Chesapeake Bay, 2006.
Dissolved Oxygen (pages 164 – 173) Figure 148. Surface dissolved oxygen in Chesapeake Bay, 2002. Figure 149. Bottom dissolved oxygen in Chesapeake Bay, 2002. Figure 150. Surface dissolved oxygen in Chesapeake Bay, 2003. Figure 151. Bottom dissolved oxygen in Chesapeake Bay, 2003. Figure 152. Surface dissolved oxygen in Chesapeake Bay, 2004. Figure 153. Bottom dissolved oxygen in Chesapeake Bay, 2004. Figure 154. Surface dissolved oxygen in Chesapeake Bay, 2005. Figure 155. Bottom dissolved oxygen in Chesapeake Bay, 2005. Figure 156. Surface dissolved oxygen in Chesapeake Bay, 2006. Figure 157. Bottom dissolved oxygen in Chesapeake Bay, 2006.
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Additional Work Performed – Serve as sampling platform for bay studies Since its inception, ChesMMAP has strived to be not just a state-of-the-art monitoring survey, but equally, a research platform from which numerous projects can benefit. We have participated in fish disease, tagging, and habitat related studies that otherwise either could not have been conducted, or would have had very substantially increased costs. For example, since 2003 ChesMMAP personnel have been collecting additional samples from striped bass to support a mycobacteriosis prevalence study conducted by scientists in the Fisheries and Environmental and Aquatic Animal Health (EAAH) Departments at VIMS. Specifically, spleen samples from these striped bass were analyzed histologically for the presence of granulomas, which are evident in diseased fish. The apparent prevalence data set derived from these samples is the most comprehensive apparent prevalence data set collected for striped bass in the bay. Subsequent modeling of those prevalence data has shown 1) the force-of-infection (rate of which disease-negative fish become disease positive) is age-dependent, 2) covariates sex and season are significant explanatory variables, and 3) that there is appreciable disease-associated mortality. In 2006, ChesMMAP personnel collected 536 striped bass tissue samples to support a trophic ecology project led by members of the Center for Quantitative Fisheries Ecology (CQFE) at Old Dominion University. Stable isotope analysis is being used to investigate the trophic interactions and position of striped bass; ultimately these data will be compared to data from traditional stomach content analysis to provide a more comprehensive description of the predatory impacts of striped bass. The costs associated with conducting both the disease monitoring and stable isotope studies in the absence of a sampling platform such as the ChesMMAP trawl survey would likely have been prohibitive. In addition to the aforementioned striped bass projects, ChesMMAP also supported the Environmental Protection Agency’s National Coastal Assessment (NCA) program by sampling 11 additional sites during the September 2006 survey. At each of these stations, up to 10 specimens of each of a number of species of interest were sacrificed for chemical and pathological analysis. Overall, 96 specimens were taken for this effort. Again, by contracting the ChesMMAP survey to conduct this relatively small amount of sampling, the cost of obtaining the resulting information was reduced substantially. And finally, ChesMMAP’s sampling efforts supported four master’s theses and a doctoral dissertation in 2006. Literature Cited Buckel, J.A., D.O. Conover, N.D. Steinberg, and K.A. McKown. 1999a. Impact of age-0 bluefish (Pomatomus saltatrix) predation on age-0 fishes in Hudson River Estuary: evidence for density-dependant loss of juvenile striped bass (Morone saxatilis). Canadian Journal of Fisheries and Aquatic Sciences 56:275-287.
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Chesapeake Bay Fisheries Ecosystem Advisory Panel. 2006. Fisheries ecosystem planning for Chesapeake Bay. American Fisheries Society, Trends in Fisheries Science and Managemen 3, Bethesda, Maryland. Hollowed, A.B., N. Bax, R. Beamish, J. Collie, M. Fogarty, P. Livingston, J. Pope, and J.C. Rice. 2000. Are multispecies models an improvement on single-species models for measuring fishing impacts on marine ecosystems? ICES Journal of Marine Science 57:707-719. Houde, E.D., M.J. Fogarty and T.J. Miller (Convenors). 1998. STAC Workshop Report: Prospects for Multispecies Fisheries Management in Chesapeake Bay. Chesapeake Bay Program, Scientific Technical Advisory Committee. Hyslop, E.J. 1980. Stomach content analysis – a review of methods and their application. Journal of Fish Biology 17:411-429. Link, J.S. 2002a. Ecological considerations in fisheries management: when does it matter? Fisheries 27(4):10-17. Link, J.S. 2002b. What does ecosystem-based fisheries management mean? Fisheries 27:18-21. NMFS (National Marine Fisheries Service). 1999. Ecosystem-based fishery management. A report to Congress by the Ecosystems Principles Advisory Panel. U. S. Department of Commerce, Silver Spring, Maryland. Miller, T.J., E.D. Houde, and E.J. Watkins. 1996. STAC Workshop Report: Prospectives on Chesapeake Bay fisheries: Prospects for multispecies fisheries management and sustainability. Chesapeake Bay Program, Scientific Technical Advisory Committee. NOAA (National Oceanic and Atmospheric Administration). 1996. Magnuson-Stevens Fishery Management and Conservation Act amended through 11 October 1996. NOAA Technical Memorandum NMFS-F/SPO-23. U. S. Department of Commerce. Pew Oceans Commission. 2003. America’s Living Oceans: Charting a Course for Sea Change. A Report to the Nation. May 2003. Pew Oceans Commission, Arlington, Virginia. U.S. Commission on Ocean Policy. An Ocean Blueprint for the 21st Century. Final Report. Washington, DC, 2004 Whipple, S. J., J. S. Link, L. P. Garrison, and M. J. Fogarty. 2000. Models of predation and fishing mortality in aquatic ecosystems. Fish and Fisheries 1:22-40.
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Figure 1. Atlantic croaker minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
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2006
M d -U p p
1 9 ,0 0 0 ,0 0 0 1 8 ,0 0 0 ,0 0 0 1 7 ,0 0 0 ,0 0 0
B.
1 6 ,0 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
1 5 ,0 0 0 ,0 0 0 1 4 ,0 0 0 ,0 0 0 1 3 ,0 0 0 ,0 0 0 1 2 ,0 0 0 ,0 0 0 1 1 ,0 0 0 ,0 0 0 1 0 ,0 0 0 ,0 0 0 9 ,0 0 0 ,0 0 0 8 ,0 0 0 ,0 0 0 7 ,0 0 0 ,0 0 0 6 ,0 0 0 ,0 0 0 5 ,0 0 0 ,0 0 0 4 ,0 0 0 ,0 0 0 3 ,0 0 0 ,0 0 0 2 ,0 0 0 ,0 0 0 1 ,0 0 0 ,0 0 0 0
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
17
M o n th Ye a r
18
March
May July
September
Figure 2. Abundance (number per hectare swept) of Atlantic croaker in Chesapeake Bay, 2002.
November
19
March May July
September
Figure 3. Abundance (number per hectare swept) of Atlantic croaker in Chesapeake Bay, 2003.
November
20
March
May July
September
Figure 4. Abundance (number per hectare swept) of Atlantic croaker in Chesapeake Bay, 2004.
November
21
March
May July
September
Figure 5. Abundance (number per hectare swept) of Atlantic croaker in Chesapeake Bay, 2005.
November
22
March May July
September
Figure 6. Abundance (number per hectare swept) of Atlantic croaker in Chesapeake Bay, 2006.
November
Figure 7. Atlantic croaker length-frequency in Chesapeake Bay 2002-2006.
2002 1 1 1 1
6 4 2 0 8 6 4 2
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
50
100
150
200
250
300
350
400
450
350
400
450
350
400
450
350
400
450
350
400
450
T o t a 2l 0L 0e 3n g t h ( m m ) 2000 1500 1000 500 0
Expanded Number
0
50
100
150
200
250
300
T o t a 2l 0L 0e 4n g t h ( m m ) 4000 3000 2000 1000 0 0
50
100
150
200
250
300
T o t a 2l 0L 0e 5n g t h ( m m ) 1 1 1 1
6 4 2 0 8 6 4 2
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
50
100
150
200
250
300
T o t a 2l 0L 0e 6n g t h ( m m ) 1200 1000 800 600 400 200 0 0
50
100
150
200
250
300
T o ta l L e n g th (m m )
23
24
Age (Year Class)
1
)
16
(1 9
88
89
)
)
70
89
(1 9
16
15
(1 9
(1 9
(1 9
87
88
89
90
)
)
)
)
0
(1 9
15
)
14
(1 9
16
15
14
13
12
(1 9
(1 9
(1 9
(1 9
(1 9
(1 9
(1 9
86
87
88
89
90
91
92
)
)
)
)
)
)
)
0
16
)
90
239
90
(1 9
13
)
8
(1 9
14
)
91
11
10
)
1
15
10
)
91
146
91
(1 9
(1 9
)
21
(1 9
13
)
12
92
)
(1 99 3
)
23
14
5
)
92
71
92
(1 9
(1 9
93
65
(1 9
12
)
11
(1 9
9
(1 99 4
)
46
13
4
)
93
223
93
(1 9
10
135
(1 9
11
)
)
8
(1 99 5
)
)
111
12
1
)
94
202
94
(1 9
(1 99 4
)
43
(1 9
10
)
9
(1 99 5
7
(1 99 6
(1 99 7
)
77
11
)
193
95
95
8
)
98
(1 9
(1 9
)
(1 99 6
6
5
(1 99 8
)
)
174
10
1000 9
96
495
)
(1 9
)
7
)
)
30
(1 99 6
477
8
97
(1 99 7
(1 99 8
4
(1 99 9
(2 00 0
)
)
84
9
640
)
(1 9
2000
(1 99 7
7
)
6
5
)
3
2
(2 00 1
(2 00 2 0
8
)
98
3000
(1 99 8
(1 9
)
(1 99 9
2000
7
6
99
232
)
(1 9
716
(1 99 9
5
)
4
)
)
1
0
4000
6
4000
)
00
(2 00 0
(2 00 1
208
(2 00 0
(2 0
)
3
2
)
)
2000
5
4
01
)
11000
)
(2 0
02
(2 00 2
(2 00 3
1000
(2 00 1
3
(2 0
1
0
487
4
3000
)
2
)
)
57
(2 00 2
)
03
04
1000
3
(2 00 3
(2 0
(2 0 51
2
0 1
0
0
)
)
0
(2 00 4
(2 00 5
0
1
0
Expanded Number Figure 8. Atlantic croaker age-structure in Chesapeake Bay 2002-2005 (2006 ages not yet assigned). 2002 3993
3000 3030
1819
1330
1000 555
0 0
Age (Year Class) 2003
7000
6000 6521
5000
4000
3000
1494
1983
672
467
0 0
Age (Year Class) 2004
10000 10726
9000
8000
7000
6000
5000
4000
1199
2352
1741
665
0 0
Age (Year Class) 2005
3955
2857
2000
2135
553
965
287
111
0
0
Figure 9. Atlantic croaker sex-ratios in Chesapeake Bay 2002-2006, by region (A), age (B).
n=
93
100
A.
209
100.0
386
1450
100.1
100.1
100.1
9.6
53.3
54.3
40.7
32.3
90
1710
100.0
44.6
80
Percent Percent
70 63.8
60
58.7
50 40
45.8
44.9
44.9
2 Md-Mid
3 Md-Low
4 Va-Upp
Sex
F M U
Sex
F M U
30 20 10 0 1 Md-Upp
5 Va-Low
Region
n = 72
Percent SUM
100
B.
99.9 97.2
475 427
335 391 349 284 214 152
61
38
25
15
12
2
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
53.3
38.4
48.6
44.8
58.3
34.8
45.9
29.4
50.0
25.0
47.6
22.9
31.7
98.1
90 80
Percent
77.1
75.0
70
70.6
68.3
65.1
60
60.5
54.5
50
54.1
52.4
50.3
50.0
45.0
40
41.7
30 20 10 0 0
1
2
3
4
5
6
7
8
AGE 25
9
10
11
12
13
14
Figure 10. Atlantic croaker length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B).
3000
A.
Weight(g)
2000
W e i g h t ( g ) = 0 .0 0 6 6 * L e n g t h ( c m ) * * 3 .1 8 3 4 ( n = 3 9 5 5 )
1000
0 0
10
20
30
40
50
T o ta l L e n g th (c m ) 3000
B.
Weight(g)
2000
Males - Weight(g) = 0.0072 * Length(cm)**3.1573 (n = 1674) Females - Weight(g) = 0.0067 * Length(cm)**3.1818 (n = 2117)
1000
0 0
10
20
30 Total Length(cm)
26
40
50
Figure 11. Atlantic croaker maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0 9 9 % m a t u r it y
0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5 5 0 % m a t u r it y
0 .4
0 .3
0 .2
0 .1
SEX
F M
0 .0
0
10
20
30
T o ta l L e n g th (c m )
Figure 12. Atlantic croaker diet in Chesapeake Bay 2002-2006 combined*.
*All samples not analyzed. 27
40
50
28
Figure 13. Black seabass minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006 (Note: abundance estimates for this species not considered reliable). R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
1 2 0 ,0 0 0
1 1 0 ,0 0 0
A.
1 0 0 ,0 0 0
Minimum Trawlable Number
9 0 ,0 0 0
8 0 ,0 0 0
7 0 ,0 0 0
6 0 ,0 0 0
5 0 ,0 0 0
4 0 ,0 0 0
3 0 ,0 0 0
2 0 ,0 0 0
1 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
Ye a r
M o n th
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th
M d -U p p
8 0 ,0 0 0
B. Minimum Trawlable Biomass (kg)
7 0 ,0 0 0
6 0 ,0 0 0
5 0 ,0 0 0
4 0 ,0 0 0
3 0 ,0 0 0
2 0 ,0 0 0
1 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
29
Ye a r
Note: This species is not captured in enough abundance to create meaningful abundance maps.
30
Figure 14. Black seabass length-frequency in Chesapeake Bay 2002-2006.
2002 8 7 6 5 4 3 2 1 0 0
50
100
150
200
250
300
200
250
300
200
250
300
200
250
300
200
250
300
T o t a l2L0e0n3g t h ( m m )
7 6 5 4 3 2 1 0
Expanded Number
0
50
100
150
T o t a l2L0e0n4g t h ( m m )
4 3 2 1 0 0
50
100
150
T o t a l2L0e0n5g t h ( m m )
3
2
1
0 0
50
100
150
T o t a l2L0e0n6g t h ( m m )
3
2
1
0 0
50
100
150
T o ta l L e n g th (m m )
31
Figure 15. Black seabass age-structure in Chesapeake Bay 2002-2003 (2004-2006 ages not yet assigned). 2 0 0 2 4 0 3 5
3 0
2 0
1 0 6 2
0 7) 5
4
(1
(1
99
99
9)
8)
0
99 (1 3
2
(2
00 1
0
(2
(2
00
1)
2) 00
0)
0
0
A g e2 ( 0 Y 0 e a3 r C l a s s ) 3 0 2 7
2 0
1 0
2
(Y e a r C la s s )
32
8)
9)
0
(1
(1 4
99
99
0) (2 3
A g e
0
00
1) 00 2
(2
00 (2 1
0
(2
00
2)
3)
0
5
1
0
Figure 16. Black seabass sex-ratios in Chesapeake Bay 2002-2006, by year (A), month (B).
n= 100
A.
48
32
100.1
100.0
18.8
96.9
14
13
17
100.0
100.0
99.9
28.6
7.7
90
7.7
80
84.6
90.9
77.1
Percent
70
14.3
60 57.1
50
Sex
40
F M U
30 20 10 0 2002
2003
2004
2005
2006
Year
n= 100
B.
25
21
71
100.0
1
100.0
6
100.0
100.0
99.9
100
17
20
19
7
90
6
87
83
80 70 Percent
81
8
72
60 50
Sex
40 30 20 10 0 03-Mar
05-May
07-Jul Month 33
09-Sep
11-Nov
F M U
Figure 17. Black seabass length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 400
A. 300
Weight(g)
W e ig h t(g ) = 0 .0 2 0 9 * L e n g th (c m )* * 2 .9 2 8 1 (n = 1 2 4 )
200
100
0 7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
T o ta l L e n g th (c m ) 400 M a le s
- W e ig h t(g ) = 0 .0 4 8 4 * L e n g th (c m )**2 .6 5 6 (n = 6 )
F e m a le s - W e ig h t(g ) = 0 .0 1 9 8 * L e n g th (c m )**2 .9 5 0 3 (n = 1 0 2 )
B.
Weight(g)
300
200
100
0 7
8
9
10
11
12
13
14
15
16
17
18
19
T o ta l L e n g th (c m )
34
20
21
22
23
24
25
26
27
Figure 18. Black seabass maturity schedule in Chesapeake Bay 2002-2006 combined (females only). 0 .9
9 9 % m a tu r it y
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a tu r it y 0 .4
0 .3
0 .2
0 .1
SEX
F
0 .0 8
9
10
11
12
13
14
15
16
17
18
19
T o ta l L e n g th (c m )
Figure 19. Black seabass diet in Chesapeake Bay 2002-2006 combined.
35
20
21
22
23
24
25
26
27
36
Figure 20. Bluefish minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006 (Note: abundance estimates for this species not considered reliable).
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
5 0 0 ,0 0 0
A.
Minimum Trawlable Number
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
4 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
B. 3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
37
M o n th Ye a r
38
March May July
Figure 21. Abundance (number per hectare swept) of bluefish in Chesapeake Bay, 2002.
September November
39
March May
July
Figure 22. Abundance (number per hectare swept) of bluefish in Chesapeake Bay, 2003.
September November
40
March May July
Figure 23. Abundance (number per hectare swept) of bluefish in Chesapeake Bay, 2004.
September November
41
March May July
Figure 24. Abundance (number per hectare swept) of bluefish in Chesapeake Bay, 2005.
September November
42
March May
July
Figure 25. Abundance (number per hectare swept) of bluefish in Chesapeake Bay, 2006.
September November
Figure 26. Bluefish length-frequency in Chesapeake Bay 2002-2006.
2002 6 5 4 3 2 1 0 0
50
100
150
200
250
300
350
400
450
500
550
400
450
500
550
400
450
500
550
400
450
500
550
400
450
500
550
F o r k 2L0e0n3 g th (m m ) 20
10
0
Expanded Number
0
50
100
150
200
250
300
350
F o r k 2L0e0n4g th (m m ) 4 3 2 1 0 0
50
100
150
200
250
300
350
5 g th (m m ) F o r k2 L0 e0 n 30 20 10 0 0
50
100
150
200
250
300
350
F o r k 2L0e0n6g th (m m ) 3 2 1 0 0
50
100
150
200
250
300
350
F o r k L e n g th (m m )
43
Figure 27. Bluefish age-structure in Chesapeake Bay 2002-2004 (2005-2006 ages not yet assigned).
2002 19
20 18 16 14 12 10 8 6 4 2 0
15
2Age 0 0(Year 3
99
7)
8)
0
4
5
(1
(1
99
9) (1 3
2
1
0
99
00 (2
00 (2
00 (2 0
0
0)
1)
2)
0
Class)
96
99
9)
5
4
(1
(1
99
00 3
0 8)
0
0)
1) 00 2
(2 1
0
(2
00
00 (2 0
6
2)
3)
10
(2
100 90 80 70 60 50 40 30 20 10 0
Age C lass) 200(Year 4 19
20 18 16 14 12 10 8 6 4 2 0
6 2
99
0)
(1 5
(2 4
3
44
00
00 (2
(2 2
Age (Year C lass)
0 9)
0
1)
2) 00
00 (2 1
0
(2
00
3)
4)
0
Figure 28. Bluefish sex-ratios in Chesapeake Bay 2002-2006, by year.
n= 100
34
68
27
71
100
100
100
100
100
17.6
16.6
14.3
10.0
8.7
44.2
34.8
90 80
23
41.2
36.6
27.1
Percent
70 60 58.6
56.5
50
Se x
46.8
40
45.8
41.2
30 20 10 0 2002
2003
2004
2005
Y ear
45
2006
F M U
Figure 29. Bluefish length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B).
3000
A.
2000 Weight(g)
We ig h t(g ) = 0 .0 0 4 4 * L e n g th (c m )**3 .3 4 3 3 (n = 2 2 9 )
1000
0
10
20
30
40
50
60
F o rk L e n g th (c m )
3000 Males
- W eight(g) = 0.0039 * Length(cm)**3.3846 (n = 86)
Females - W eight(g) = 0.0049 * Length(cm)**3.3166 (n = 111)
B.
Weight(g)
2000
1000
0
10
20
30
40
F o rk L e n g th (c m )
46
50
60
Figure 30. Bluefish maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0 9 9% ma tu r ity
0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5 5 0% ma tu r ity
0 .4
0 .3
0 .2
0 .1
SE X
F M
0 .0
10
20
30
40
Fork Le ngth (cm )
Figure 31. Bluefish diet in Chesapeake Bay 2002-2006 combined.
47
50
60
48
Figure 32. Butterfish minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
3 ,0 0 0 ,0 0 0
Minimum Trawlable Number
A.
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
Ye a r
M o n th
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th
M d -U p p
3 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
B.
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
49
Ye a r
50
March May
July
Figure 33. Abundance (number per hectare swept) of butterfish in Chesapeake Bay, 2002.
September November
51
March May
July
Figure 34. Abundance (number per hectare swept) of butterfish in Chesapeake Bay, 2003.
September November
52
March May July
Figure 35. Abundance (number per hectare swept) of butterfish in Chesapeake Bay, 2004.
September November
53
March May July
Figure 36. Abundance (number per hectare swept) of butterfish in Chesapeake Bay, 2005.
September November
54
March May
July
Figure 37. Abundance (number per hectare swept) of butterfish in Chesapeake Bay, 2006.
September November
Figure 38. Butterfish length-frequency in Chesapeake Bay 2002-2006.
2002 60 50 40 30 20 10 0 0
50
100
150
200
250
300
2 50
30 0
2 5 0
3 0 0
250
300
250
300
3 g th (m m ) T o t a l2 L0 e0 n 3 00 2 00 1 00 0 0
50
1 00
1 50
2 00
Expanded Number
00 T o ta 2 l L e4 n g th (m m ) 3 0 0 2 0 0 1 0 0 0 0
5 0
1 0 0
1 5 0
20 0
T o t a l 2L0e0n5g t h ( m m ) 100 80 60 40 20 0 0
50
100
150
200
T o t a l 2L0e0n6 g t h ( m m ) 8 7 6 5 4 3 2 1
0 0 0 0 0 0 0 0 0 0
50
100
150
200
T o ta l L e n g th (m m )
55
Figure 39. Butterfish length-weight relationship in Chesapeake Bay 2002-2006 as calculated by power regression. 300
Weight(g)
200
We ight(g) = 0.0146 * Le ngth(cm )**3.1672 (n = 1408)
100
0
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Fork Le ngth(cm )
Figure 40. Butterfish diet in Chesapeake Bay 2002-2006 combined (Note: nearly all samples from 2002).
56
21
22
Figure 41. Northern kingfish minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
5 0 0 ,0 0 0
A. Minimum Trawlable Number
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
1 8 0 ,0 0 0 1 7 0 ,0 0 0 1 6 0 ,0 0 0
B.
1 5 0 ,0 0 0
Minimum Trawlable Biomass (kg)
1 4 0 ,0 0 0 1 3 0 ,0 0 0 1 2 0 ,0 0 0 1 1 0 ,0 0 0 1 0 0 ,0 0 0 9 0 ,0 0 0 8 0 ,0 0 0 7 0 ,0 0 0 6 0 ,0 0 0 5 0 ,0 0 0 4 0 ,0 0 0 3 0 ,0 0 0 2 0 ,0 0 0 1 0 ,0 0 0 0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
57
M o n th Ye a r
58
March May July
September
Figure 42. Abundance (number per hectare swept) of northern kingfish in Chesapeake Bay, 2002.
November
59
March May July
September
Figure 43. Abundance (number per hectare swept) of northern kingfish in Chesapeake Bay, 2003.
November
60
March May
July
September
Figure 44. Abundance (number per hectare swept) of northern kingfish in Chesapeake Bay, 2004.
November
61
March May
July
September
Figure 45. Abundance (number per hectare swept) of northern kingfish in Chesapeake Bay, 2005.
November
62
March May
July
September
Figure 46. Abundance (number per hectare swept) of northern kingfish in Chesapeake Bay, 2006.
November
Figure 47. Northern kingfish length-frequency in Chesapeake Bay 2002-2006.
2 0 0 2 1 1 1 1
6 4 2 0 8 6 4 2 0 0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
3 5 0
4 0 0
4 5 0
3 5 0
4 0 0
4 5 0
3 5 0
4 0 0
4 5 0
3 5 0
4 0 0
4 5 0
T o t a l 2L 0e0n3g t h ( m m ) 1 0 8 6 4 2 0
Expanded Number
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
T o t a l 2L 0e0n4g t h ( m m ) 1 4 1 2 1 0 8 6 4 2 0 0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
T o ta l L e n g th (m m ) 2 0 0 5 1 0 8 6 4 2 0 0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
T o t a l 2L 0e0n6g t h ( m m ) 2 0 1 5 1 0 5 0 0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
T o ta l L e n g th (m m ) 63
Figure 48. Northern kingfish sex-ratios in Chesapeake Bay 2002-2006, by year (A), month (B).
n= 100
A.
90
73
55
55
71
100.1
100.0
100.1
100.0
100.0
9.7
34.3
9.0
20.2
49.7
35.5
39.4
Percent
80
21.7
70 64.2
60
58.1
55.6
50
51.0
49.2
Sex
40
F M U
30 20 10 0 2002
2003
2004
2005
2006
Year
n= 100
B.
51
63
130
100
100
100
100
42.7
53.7
6.0
27.3
76
33.0
90 80 70
Percent Percent
Percent
66
20.7
60
61.0
57.3
50
52.0
45.2
40 30 20 10 0 05-May
07-Jul
09-Sep Month 64
11-Nov
Sex
F M U
Figure 49. Northern kingfish length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B).
700
A.
600
Weight(g)
500
400 W e ig h t ( g ) = 0 .0 0 6 8 * L e n g t h ( c m ) * * 3 .1 4 5 ( n = 3 3 9 )
300
200
100
0
0
10
20
30
40
Total Length(cm )
700
B.
600
M a le s
500
- W e ig h t ( g ) = 0 .0 1 0 9 * L e n g t h ( c m ) * * 2 .9 9 9 ( n = 1 1 0 )
Weight(g)
F e m a le s - W e ig h t ( g ) = 0 .0 0 6 4 * L e n g t h ( c m ) * * 3 .1 6 6 ( n = 1 7 9 )
400
300
200
100
0
10
20
30 Total Length(cm ) 65
40
Figure 50. Northern kingfish maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0 9 9 % m a t u r it y
0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5 5 0 % m a t u r it y
0 .4
0 .3
0 .2
0 .1
S E X 20. Northern F Figure kingfish diet in Chesapeake Bay 2002-2005 combined*. M
0 .0
10
20
30
T o ta l L e n g th (c m )
Figure 51. Northern kingfish diet in Chesapeake Bay 2002-2006 combined.
66
40
67
Figure 52. Northern puffer minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
6 0 0 ,0 0 0
A. Minimum Trawlable Number
5 0 0 ,0 0 0
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
1 6 0 ,0 0 0 1 5 0 ,0 0 0 1 4 0 ,0 0 0
B.
Minimum Trawlable Biomass (kg)
1 3 0 ,0 0 0 1 2 0 ,0 0 0 1 1 0 ,0 0 0 1 0 0 ,0 0 0 9 0 ,0 0 0 8 0 ,0 0 0 7 0 ,0 0 0 6 0 ,0 0 0 5 0 ,0 0 0 4 0 ,0 0 0 3 0 ,0 0 0 2 0 ,0 0 0 1 0 ,0 0 0 0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
68
M o n th Ye a r
Note: This species is not captured in enough abundance to create meaningful abundance maps.
69
Figure 53. Northern puffer length-frequency in Chesapeake Bay 2002-2006.
2 0 0 2 3 0 2 0 1 0 0
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
2 5 0
3 0 0
2 5 0
3 0 0
2 5 0
3 0 0
2 5 0
3 0 0
T o t a l 2L0 e0 n3 g t h ( m m ) 4 0 3 0 2 0 1 0 0
Expanded Number
0
5 0
1 0 0
1 5 0
2 0 0
T o t a l 2L 0e 0n4g t h ( m m ) 7 6 5 4 3 2 1 0
0
5 0
1 0 0
1 5 0
2 0 0
T o t a l 2 L0 e0 n5 g t h ( m m ) 3 0 2 0 1 0 0
0
5 0
1 0 0
1 5 0
2 0 0
T o t a l 2L0 e0 n6 g t h ( m m ) 1 2 1 0 8 6 4 2 0
0
5 0
1 0 0
1 5 0
2 0 0
T o ta l L e n g th (m m )
70
Figure 54. Northern puffer sex-ratios in Chesapeake Bay 2002-2006, by year (A), month (B).
n= 100
A.
134
97
31
84
9 9 .9
1 0 0 .1
1 0 0 .0
1 0 0 .0
1 0 0 .1
1 3 .3
3 1 .6
1 8 .0
1 3 .5
3 4 .5
51
90 4 6 .2
3 6 .9
2 7 .0
70 6 7 .9
60
6 3 .1
5 5 .0
50
S ex
4 9 .7
40
F M U
4 0 .4
30 20 10 0 2002
2003
2004
2005
2006
Year
n= 100
B.
14
76
105
202
1 0 0 .0
1 0 0 .1
1 0 0 .0
1 0 0 .0
2 1 .4
6 2 .3
2 0 .7
8 .0
90
2 2 .9
80
3 6 .7
2 8 .6
70 6 9 .1
Percent Percent
Percent
Percent
80
60 50
S ex
5 0 .0
40
4 2 .6 3 6 .0
30 20 10 0 0 5 -M a y
0 7 -J u l
0 9 -S e p
M o n th 71
1 1 -N o v
F M U
Figure 55. Northern puffer length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 600
A. 500
Weight(g)
400
300
W e i g h t ( g ) = 0 .0 3 7 * L e n g t h ( c m ) * * 2 .8 8 5 8 ( n = 4 4 3 )
200
100
0 0
10
20
30
T o ta l L e n g th (c m ) 600
B. 500
400
M a le s
- W e i g h t ( g ) = 0 .0 3 3 2 * L e n g t h ( c m ) * * 2 .9 0 3 9 ( n = 1 3 7 )
Weight(g)
F e m a l e s - W e i g h t ( g ) = 0 .0 5 5 7 * L e n g t h ( c m ) * * 2 .7 5 6 9 ( n = 2 2 1 ) 300
200
100
0 0
10
20 T o ta l L e n g th (c m )
72
30
Figure 56. Northern puffer maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0
9 9 % m a tu r it y 0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a tu r it y 0 .4
0 .3
0 .2
0 .1
SEX 0 .0 0
F M 10
20
T o ta l L e n g th (c m )
Figure 57. Northern puffer diet in Chesapeake Bay 2002-2006 combined.
73
30
74
Figure 58. Scup minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
4 ,0 0 0 ,0 0 0
A. Minimum Trawlable Number
3 ,0 0 0 ,0 0 0
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
Ye a r
M o n th
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th
M d -U p p
2 0 0 ,0 0 0 1 9 0 ,0 0 0 1 8 0 ,0 0 0
B.
1 7 0 ,0 0 0
Minimum Trawlable Biomass (kg)
1 6 0 ,0 0 0 1 5 0 ,0 0 0 1 4 0 ,0 0 0 1 3 0 ,0 0 0 1 2 0 ,0 0 0 1 1 0 ,0 0 0 1 0 0 ,0 0 0 9 0 ,0 0 0 8 0 ,0 0 0 7 0 ,0 0 0 6 0 ,0 0 0 5 0 ,0 0 0 4 0 ,0 0 0 3 0 ,0 0 0 2 0 ,0 0 0 1 0 ,0 0 0 0
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
75
Ye a r
76
March May
July
Figure 59. Abundance (number per hectare swept) of scup in Chesapeake Bay, 2002.
September November
77
March May
July
Figure 60. Abundance (number per hectare swept) of scup in Chesapeake Bay, 2003.
September November
78
March May July
Figure 61. Abundance (number per hectare swept) of scup in Chesapeake Bay, 2004.
September November
79
March May July
Figure 62. Abundance (number per hectare swept) of scup in Chesapeake Bay, 2005.
September November
80
March May
July
Figure 63. Abundance (number per hectare swept) of scup in Chesapeake Bay, 2006.
September November
Figure 64. Scup length-frequency in Chesapeake Bay 2002-2006.
2 0 0 2 4 0 3 0 2 0 1 0 0
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
F o r k 2L0e0n3g t h ( m m ) 7 6 5 4
0 0 0 0
3 0 2 0 1 0 0
Expanded Number
0
5 0
1 0 0
1 5 0
2 0 0
F o r k 2 L0 e0 n4 g t h ( m m ) 1 1 1 1
6 4 2 0 8 6 4 2
0 0 0 0 0 0 0 0 0 0
5 0
1 0 0
1 5 0
2 0 0
F o r k 2 L0 e0 n5 g t h ( m m ) 3 0 0
2 0 0
1 0 0
0 0
5 0
1 0 0
1 5 0
2 0 0
F o r k 2L0e0n6g t h ( m m ) 8 7 6 5 4 3 2 1
0 0 0 0 0 0 0 0 0 0
5 0
1 0 0
1 5 0
2 0 0
F o rk L e n g th (m m )
81
Figure 65. Scup sex-ratios in Chesapeake Bay 2002-2005, by year (A) and month (B).
n= 100
A.
40
97
1 0 0 .0
1 0 0 .0
155 1 0 0 .1
1 0 0 .0
85
115 9 9 .9
2 3 .3
3 1 .8
4 9 .5
3 7 .0
7 6 .8
90 80
2 7 .5 2 9 .5
60 50
1 0 .7
40
4 0 .7
Se x
F M U
3 9 .9 3 3 .5
30
2 9 .9
20
8 .5
10
1 4 .6
0 2002
2003
2004
2005
2006
Year
n= 100
B.
34
124
255
79
100
100
100
100
8 6 .2
6 4 .4
4 0 .0
1 5 .4
90 2 8 .8
80 70 Percent Percent
Percent
Percent
4 6 .8
70
60
2 8 .0 5 5 .8
50
Se x
40 5 .6
30
3 2 .0
3 0 .0
20 10
1 3 .8
0 0 5 -M a y
0 7 -J u l
0 9 -S e p M o n th
82
1 1 -N o v
F M U
Figure 66. Scup length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B).
300
A.
Weight(g)
200
W e ig h t(g ) = 0 .0 2 3 6 * L e n g th (c m )**2 .9 8 0 6 (n = 4 9 6 )
100
0 6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
T o ta l L e n g th (c m ) 300
B. 200
M a le s
- W e ig h t(g ) = 0 .0 4 0 1 * L e n g th (c m )**2 .7 9 9 (n = 1 0 4 )
Weight(g)
F e m a le s - W e ig h t(g ) = 0 .0 2 4 3 * L e n g th (c m )**2 .9 7 4 6 (n = 1 8 4 )
100
0 8
9
10
11
12
13
14
15
16
17
T o ta l L e n g th (c m )
83
18
19
20
21
22
23
Figure 67. Scup maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0
9 9 % m a tu r it y 0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a tu r it y 0 .4
0 .3
0 .2
0 .1
SEX
F M
0 .0 8
9
10
11
12
13
14
15
16
F o r k L e n g th (c m )
Figure 68. Scup diet in Chesapeake Bay 2002-2006 combined.
84
17
18
19
20
21
22
23
Figure 69. Spot minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
1 9 ,0 0 0 ,0 0 0 1 8 ,0 0 0 ,0 0 0 1 7 ,0 0 0 ,0 0 0 1 6 ,0 0 0 ,0 0 0
A.
1 5 ,0 0 0 ,0 0 0
Minimum Trawlable Number
1 4 ,0 0 0 ,0 0 0 1 3 ,0 0 0 ,0 0 0 1 2 ,0 0 0 ,0 0 0 1 1 ,0 0 0 ,0 0 0 1 0 ,0 0 0 ,0 0 0 9 ,0 0 0 ,0 0 0 8 ,0 0 0 ,0 0 0 7 ,0 0 0 ,0 0 0 6 ,0 0 0 ,0 0 0 5 ,0 0 0 ,0 0 0 4 ,0 0 0 ,0 0 0 3 ,0 0 0 ,0 0 0 2 ,0 0 0 ,0 0 0 1 ,0 0 0 ,0 0 0 0
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
2 ,0 0 0 ,0 0 0 1 ,9 0 0 ,0 0 0 1 ,8 0 0 ,0 0 0
B.
1 ,7 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
1 ,6 0 0 ,0 0 0 1 ,5 0 0 ,0 0 0 1 ,4 0 0 ,0 0 0 1 ,3 0 0 ,0 0 0 1 ,2 0 0 ,0 0 0 1 ,1 0 0 ,0 0 0 1 ,0 0 0 ,0 0 0 9 0 0 ,0 0 0 8 0 0 ,0 0 0 7 0 0 ,0 0 0 6 0 0 ,0 0 0 5 0 0 ,0 0 0 4 0 0 ,0 0 0 3 0 0 ,0 0 0 2 0 0 ,0 0 0 1 0 0 ,0 0 0 0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
85
M o n th Ye a r
86
March May
July
Figure 70. Abundance (number per hectare swept) of spot in Chesapeake Bay, 2002.
September November
87
March May
July
Figure 71. Abundance (number per hectare swept) of spot in Chesapeake Bay, 2003.
September November
88
March May July
Figure 72. Abundance (number per hectare swept) of spot in Chesapeake Bay, 2004.
September November
89
March May
July
Figure 73. Abundance (number per hectare swept) of spot in Chesapeake Bay, 2005.
September November
90
March May
July
Figure 74. Abundance (number per hectare swept) of spot in Chesapeake Bay, 2006.
September November
Figure 75. Spot length-frequency in Chesapeake Bay 2002-2006.
2 0 0 2 5 0 0 4 0 0 3 0 0 2 0 0 1 0 0 0
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
2 5 0
3 0 0
3 5 0
F o r k 2 L0 e0 n3 g t h ( m m ) 7 6 5 4 3 2 1
0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
Expanded Number
0
5 0
1 0 0
1 5 0
2 0 0
F o r k 2 L0 e0 n4 g t h ( m m ) 7 6 5 4 3 2 1
0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0
5 0
1 0 0
1 5 0
2 0 0
F o r k 2 L0 e0 n5 g t h ( m m ) 1 4 0 0 1 2 0 0 1 0 0 0 8 0 0 6 0 0 4 0 0 2 0 0 0
0
5 0
1 0 0
1 5 0
2 0 0
F o r k2 0L 0e 6n g t h ( m m ) 1 1 1 1
6 4 2 0 8 6 4 2
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0
5 0
1 0 0
1 5 0
2 0 0
F o rk L e n g th (m m )
91
Figure 76. Spot age-structure in Chesapeake Bay 2002-2006. 2 0 0 2 1 8 0 0
1 6 5 1
1 6 0 0 1 4 0 0 1 2 0 0 9 5 4
1 0 0 0 8 0 0 6 0 0 4 0 0
2 0 0( Y3 e
A g e
0 7
)
)
99
99
5
4
(1
(1
99 (1
2
3
(2
(2 1
1
9
)
00
00
1
0
)
) 2 00 (2 0
2 4
)
8 4
0
8
2 0 0
a r C la s s )
3 0 0 0
2 2 8 0
2 0 0 0
1 2 7 2
0( Y4e
8
9
99
99
5
4
(1
(1
00 (2
A2g 0 e
0
)
) 0
) 2
1
3
(2
(2
00
00
2
1
)
) 3 00 (2 0
2
0
)
3 1
0
a r C la s s )
3 0 0 0 2 6 2 2
2 0 0 0
1 2 6 5
1 0 0 0
1 8 6 ) 9 99 5
4
3
2
0( Y5 e
(1
00 (2
00 (2
00 (2
00 (2 1
2 g0e A
0
0
) 1
) 2
) 3
) 4 00 (2 0
0 )
2
0
a r C la s s )
8 0 0 0 7 1 2 3
7 0 0 0 6 0 0 0 5 0 0 0 4 0 7 2
4 0 0 0 3 0 0 0 2 0 0 0 1 0 0 0 )
)
00
1
(2 5
4
2
3
(2
(2
00
00 (2
00 (2 1
A g e
2006
0
00
2
3
)
)
) 4
) 5 00 (2 0
2
2 0
0
1 5 3
0
( Y e a r C la s s )
3865
4000
2835
3000 2000 1000
89
0
0
0
92
1) 00 (2
(2
00
5
3
A g e (Y e a r C la s s )
4
(2
00
2)
3)
4) 00 2
(2
00 (2 1
(2
00
5)
6)
0
0
Expanded Number
1 0 0 0
Figure 77. Spot sex-ratios in Chesapeake Bay 2002-2005, by year (A), month (B).
n= 100
A.
672
380
617
1023
100
100
100
100
1 3 .8
6 .5
1 7 .4
1 3 .6
100
4 0 .9
4 8 .3
90
680
3 9 .3
4 4 .8
80
3 8 .2
Percent Percent
70 60 5 5 .3
50 40
Se x
4 5 .2
4 4 .4
2003
2004
4 1 .4
4 7 .1
F M U
30 20 10 0 2002
2005
2006
Y ear
n= 100
B.
4
433
802
1304
100
100
100
100
100
100
19
11
7
15
90
829
46
42 34
80
39
Percent Percent
70 60 50
51
40
47
47
0 7 -J u l
0 9 -S e p
43
30 20 10 0 0 3 -M a r
0 5 -M a y
M o n th 93
1 1 -N o v
Se x
F M U
Figure 78. Spot length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 600
A. 500
Weight(g)
400
W e ig h t(g ) = 0 .0 0 8 * L e n g th (c m )**3 .2 5 8 (n = 3 4 1 3 )
300
200
100
0 0
10
20
30
40
F o r k L e n g th (c m )
600 M a le s
- W e ig h t ( g ) = 0 .0 0 8 7 * L e n g t h ( c m ) * * 3 . 2 2 9 6 ( n = 1 2 9 9 )
F e m a le s - W e ig h t ( g ) = 0 .0 0 7 6 * L e n g t h ( c m ) * * 3 . 2 7 4 2 ( n = 1 5 7 9 )
500
B.
Weight(g)
400
300
200
100
0 0
10
20 F o r k L e n g th (c m )
94
30
40
Figure 79. Spot maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0
9 9 % m a t u r it y 0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a t u r it y 0 .4
0 .3
0 .2
0 .1
SEX
F M
0 .0 0
10
20
F o r k L e n g th (c m )
95
30
40
96
Figure 80. Striped bass minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
4 ,0 0 0 ,0 0 0
A. Minimum Trawlable Number
3 ,0 0 0 ,0 0 0
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
3 ,0 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
B.
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
97
M o n th Ye a r
98
March May
July
September
Figure 81. Abundance (number per hectare swept) of striped bass in Chesapeake Bay, 2002.
November
99
March May
July
September
Figure 82. Abundance (number per hectare swept) of striped bass in Chesapeake Bay, 2003.
November
100
March May
July
September
Figure 83. Abundance (number per hectare swept) of striped bass in Chesapeake Bay, 2004.
November
101
March May
July
September
Figure 84. Abundance (number per hectare swept) of striped bass in Chesapeake Bay, 2005.
November
102
March May July
September
Figure 85. Abundance (number per hectare swept) of striped bass in Chesapeake Bay, 2006.
November
Figure 86. Striped bass length-frequency in Chesapeake Bay 2002-2006.
2002 30 20 10 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
700
750
800
850
900
950
1000
700
750
800
850
900
950
1000
700
750
800
850
900
950
1000
700
750
800
850
900
950
1000
F o r k 2L0e0n3g t h ( m m ) 50 40 30 20 10 0
Expanded Number
0
50
100
150
200
250
300
350
400
450
500
550
600
650
F o r k 2L0e0n4g t h ( m m ) 50 40 30 20 10 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
5 g th (m m ) F o r k 2 L0 e0 n
200 150 100 50 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
F o r k 2L0e0n6g t h ( m m ) 7 6 5 4 3 2 1
0 0 0 0 0 0 0 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
F o rk L e n g th (m m )
103
104
A g e (Y e a r C la s s )
0)
1
9
1 6 (1 9
9
8
9
9)
0)
0
9
(1
1
1
6
5
(1
(1
(1
98
98
99
8)
9)
0)
1)
1
(1
5
1)
4
99
1
1
1
1
1
6
5
4
3
2
(1
(1
(1
(1
(1
(1
98
98
98
99
99
99
7)
8)
9)
0)
1)
2)
3)
0
6
1
9
1
(1
2)
1
99
1
1
1
1
1
1
1
6
5
4
3
2
1
0
9
(1
(1
(1
(1
(1
(1
(1
(1
98
98
98
98
99
99
)
)
)
)
)
6)
7)
8)
9)
0)
1)
2)
93
94
95
96
99
9
9
9
9
97
)
)
0
1
1)
4
9
9
0
9
(1
3
99
0
(1
4
2)
1
(1
3)
(1
3
5
1
9
2
99
1
0
)
(1
(1
(1
9
98
99
)
0
1
2)
9
9
9
4
9
(1
1
(1
1
(1
3
3)
1
4)
94
0
4
1
9
1
99
9
8
7
6
(1
9
9
00
2
1
6
3)
1 9
9
9
2
9
(1
4)
(1
9
(1
2
9
0
(1
)
)
1
3
1
9
1
1
9
95
96
)
5
(1
(1
0
)
)
2
1
4)
(1
7
9
1
5)
)
7
9
1
9
95
9
9
97
10
(1
5)
9
9
(1
(1
9
)
4
3
(2
01
02
1
2
9
(1
(1
)
8
7
(1
98
)
)
2
0
0
9
1
9
1 0
(1
0
1 4
1
1
9
96
)
8
1
5
6)
1 3 )
4
9
0 6
9
97
2
9
99
(1
9
6
9
99
00
)
21
(1
(1
8
(1
)
(1
9
0
01
(2
(2
3
0
9
)
7
98
)
5
(1
(2
0
1
0
13
1
0( Y0 e6 a
)
7
1 4
7
99
)
9
99
21
99
(1
8
(1
9
)
4
3
(2
)
)
22
(1
8
99
6
(1
00
)
2
02
03
4
9
)
1 9
8
A g2 e
99
(1
6
(1
7
)
5
0
01
18
8
1 3
)
9
1
9
99
2 5
99
(1
)
(2
0
19
(1
6
0
4
(2
)
0
0
18
7
5 0
)
5 0
0
00
)
5 0
00
(2
1
3
02
(2
(2
5
(2
5
00
)
0
)
1
0
0
6
2 5
)
(2
2
1 5 0
1
4
00
(2
03
)
93
00
)
(2
2
0
04
100
(2
2
3
)
(2
0
34
5
00
6 0 0
(2
)
3
1 0 0
4
3
00
1 8 0 0
00
(2
1
(2
100
(2
)
)
0
163
3
4
4
)
7 5
00
00
5
300
(2
2
(2
00
2
2
)
(2
0
5
1
0
0
00
0
)
0
(2
6
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1
00
7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1
(2
1 1 1 1 1 1 1 1
0
Expanded Number Figure 87. Striped bass age-structure in Chesapeake Bay 2002-2006. 2002
157
28 51
0 0
A2g 0e 0( Y3e a r C l a s s )
300
254
200
167
76 42 25 0 0
0 e4a r C l a s s ) A g2e 0( Y
273 290
200
96
25 2 2
2 g0e 0( Y5e a r C l a s s ) A
1 7 0 0 1 7 3 4
2 0 0
1 7 5
1 4 9
1 2 5
7 3 9 9
5 0
0 0
r C la s s )
5 0 0
5 5 1
2 0 0
1 7 5
1 5 0
1 5 0
1 2 5
1 0 0
7 5
4 7
0
0
Figure 88. Striped bass sex-ratios in Chesapeake Bay 2002-2006, by year (A), month (B), age (C).
n= 100
467
584
724
100.0
100.0
99.9
100.0
100.0
4.8
59.3
6.0
53.2
67.3
63.3
90
A.
337
535
53.0
80 70
Percent
Percent
60 50
Sex
F M U
Sex
F M U
Sex
F M U
45.2
40
40.9
39.2
30
31.9
31.6
20 10 0 2002
2003
2004
2005
2006
Year
n=
1137
B.
350
100.0
100
211
100.0
48.1
149
99.9
77.0
68.2
90
800
100.1
100.0
66.0
60.9
80
Percent
Percent
70 60 50 48.3
40 38.5
30
32.4
27.6
20 19.3
10 0 03-Mar
05-May
07-Jul
09-Sep
11-Nov
Month
n=
Percent SUM
100
5
263 725 363 256 83
57
73
44
100.0
100.0
100.1
100.0
100.0
100.0
100.0
100.0
100.0
58
19
52
52
77
88
93
81
72
48
48
38 100.0
30
2
2
100.0
14 100.0
7 100.0
3 100.0
1 100.0
100.0
100.0
78
64
71
100
100
50
50
50
50
15
16
83
90
C.
80
41
70 60
Percent
50 40
23
40 36
30 29
28
20
23
22
19
19 15
10
12 7
0 0
1
2
3
4
5
6
7
8
9
AGE
105
10
11
12
13
14
Figure 89. Striped bass length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 16000 15000 14000
A.
13000 12000 11000
W e ig h t(g ) = 0 .0 0 9 3 * L e n g th (c m )**3 .0 6 6 2 (n = 2 6 8 9 )
Weight(g)
10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 0
10
20
30
40
50
60
70
80
90
100
110
80
90
100
110
F o rk L e n g th (c m )
16000 M a le s
15000
- W e ig h t(g ) = 0 .0 0 9 3 * L e n g th (c m )**3 .0 6 8 1 (n = 1 6 2 4 )
F e m a le s - W e ig h t(g ) = 0 .0 0 8 5 * L e n g th (c m )**3 .0 8 5 5 (n = 9 6 6 )
14000 13000
B.
12000 11000
Weight(g)
10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 0
10
20
30
40
50
60
F o rk L e n g th (c m )
106
70
Figure 90. Striped bass maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0
9 9 % m a tu r ity 0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a tu r ity 0 .4
0 .3
0 .2
0 .1
SEX
F M
0 .0 0
10
20
30
40
50
60
F o r k L e n g th (c m ) Figure 40. Striped bass diet in Chesapeake Bay 2002-2005 combined.
Figure 91. Striped bass diet in Chesapeake Bay 2002-2006 combined.
107
70
80
90
100
110
108
Figure 92. Summer flounder minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
1 ,6 0 0 ,0 0 0 1 ,5 0 0 ,0 0 0
A.
1 ,4 0 0 ,0 0 0 1 ,3 0 0 ,0 0 0
Minimum Trawlable Number
1 ,2 0 0 ,0 0 0 1 ,1 0 0 ,0 0 0 1 ,0 0 0 ,0 0 0 9 0 0 ,0 0 0 8 0 0 ,0 0 0 7 0 0 ,0 0 0 6 0 0 ,0 0 0 5 0 0 ,0 0 0 4 0 0 ,0 0 0 3 0 0 ,0 0 0 2 0 0 ,0 0 0 1 0 0 ,0 0 0 0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
1 ,0 0 0 ,0 0 0
9 0 0 ,0 0 0
B.
Minimum Trawlable Biomass (kg)
8 0 0 ,0 0 0
7 0 0 ,0 0 0
6 0 0 ,0 0 0
5 0 0 ,0 0 0
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
109
M o n th Ye a r
110
March May
July
Figure 93. Site-specific summer flounder abundance (number per hectare swept), 2002.
September November
111
March May
July
Figure 94. Site-specific summer flounder abundance (number per hectare swept), 2003.
September November
112
March May
July
Figure 95. Site-specific summer flounder abundance (number per hectare swept), 2004.
September November
113
March May July
Figure 96. Site-specific summer flounder abundance (number per hectare swept), 2005.
September November
114
March May July
Figure 97. Site-specific summer flounder abundance (number per hectare swept), 2007.
September November
Figure 98. Summer flounder length-frequency in Chesapeake Bay 2002-2006.
2002 60 50 40 30 20 10 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
550
600
650
700
750
800
550
600
650
700
750
800
550
600
650
700
750
800
550
600
650
700
750
800
00 T o ta l2 L e3 n g th (m m ) 50 40 30 20 10 0
Expanded Number
0
50
100
150
200
250
300
350
400
450
500
T o ta 2l 0L0e4n g th (m m ) 120 100 80 60 40 20 0 0
50
100
150
200
250
300
350
400
450
500
00 T o t a l2 L e5 n g th (m m ) 60 50 40 30 20 10 0 0
50
100
150
200
250
300
350
400
450
500
T o ta2l 0L0e6n g th (m m ) 120 100 80 60 40 20 0 0
50
100
150
200
250
300
350
400
450
500
T o ta l L e n g th (m m )
115
Figure 99. Summer flounder age-structure in Chesapeake Bay 2002-2006. 2 0 0 2 4 0 0
3 7 7
3 0 0
2 0 0 1 1 5
9 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
) 0 99
1
(1 12
(1 11
(1 10
(1 9
8
0
)
) 2
4) 99 (1
99 (1 7
0
C la s s )
6 9 4 5
3 2
)
)
0 1
2
3 99
99 12
(1
(1 11
(1 10
(1 9
8
0
)
0
4)
5) 99 (1
99 (1 7
6 Y e a r 2 0A g 0e ( 4
0
99
2
6)
7) 99 (1
99 5
(1
(1 4
5
99
9
8)
9) 99
0) 00 3
(2
(2 2
(2 1
0
(2
00
00
2)
1)
1 3
C la s s )
5 0 0 4 1 1
4 0 0
3 0 0
2 0 0 1 1 4
1 0 0
1 0 0
7 1
) 2
)
99 12
10
11
(1
(1
(1
99
99
3
4
5) (1
8
2
0
)
0
9
(1
99 (1 7
6
2 A0g e 0( Y 5e a r
1
6)
7)
8) 99 (1
99 (1 5
6
2
99
1 3
9)
0) 4
3
(2
(2
00
00
1)
2) 00 (2 2
(2 1
0
(2
00
00
3)
4)
0
99
3 6
2 7
C la s s )
2 9 3
3 0 0
2 0 2
2 0 0
8 8
7 8
2 4
2 1 3
)
)
0
11
12
(1
(1
99
99
4
5 (1 10
(1 9
8
0
)
0 99
7) 99 (1
99 (1 7
6
2 0A g0e 6( Y e a r
5
2
8)
9) (1
00 5
(2
(2 4
99
0)
1) 00
2) 3
(2
(2 2
(2 1
00
00
00
4)
5) 00 (2 0
3)
4
6)
2 8
0
99
1 0 0
C la s s )
5 0 0 4 4 6
4 0 0
3 0 0
2 0 0 1 4 9
9 7
7 0
) 99 (1 12
11
(1
99
4
)
0
5
) (1 10
9
(1
99
99
6
7)
8)
1
2
1
99 8
(1
99
A g e ( Y e a r C la s s )
116
3
9)
0) 00 6
(2
00 5
(2
00 (2 4
1 7
1 5
1)
2)
3) 3
(2
00 (2 2
(2 1
00
5) 00
6) 00 (2
4)
2 4
0
(1
6 0
7
1 0 0
0
Expanded Number
0
1 5 3
1 5 0
3)
6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1
00
1 1 1 1 1 1 1
5)
6) 6
4
5
(1
(1
99
99
7)
8) (1
99 3
(1
(2 2
(2 1
99
9)
0) 00
00
1)
2) 00 (2 0
Y e a r 2 0A g 0e ( 3
2
1
1
99
2 0
99
2 2
3)
2 6
0
99
8 6
1 0 0
Figure 100. Summer flounder sex-ratios in Chesapeake Bay 2002-2006, by month (A), region (B), age (C).
n=
242 7.4
90
A.
336
100
100
473
959
1028
100
100
100
100
20.1
20.6
29.0
37.9
77.2
76.3
15.7
80 76.9
70
Percent
68.0 Percent
60 58.9
50
Sex
F M U
Sex
F M U
Sex
F M U
40 30 20 10 0 03-M ar
05-M ay
07-Jul
09-Se p
11-Nov
M onth
n= 100
Percent
Percent
B.
14
163
285
100.0
100.0
100.1
99.9
48.9
4.9
37.1
5.0
1012
36.8
90
1564 100.0
28.8
27.8
80 70 68.7
67.1
60
61.3
58.3
50
51.1
40 30 20 10 0 1 M d-Upp
2 M d-M id
3 M d-Low
4 Va-Upp
5 Va-Low
Re gion
n = 1114 716
Percent SUM
100 90
100.0 5
47
100.1 4
354
276
100.0
100.0
7
4
96
32 93
194 100.0 5
95
114 100.0 4
78
28
14
9
2
1
100.0
100.0
100.0
100.0
100.0
100.0
100.0
2
8
100
7
11
100
100
50
96 93
92
89
Percent
C.
80 70 64
60 50
50
48
40 30 20 10 0 0
1
2
3
4
5
6 AGE
117
7
8
9
10
11
12
Figure 101. Summer flounder length-weight relationships in Chesapeake Bay 2002-2005 as calculated by power regression for sexes combined (A) and separately (B). 6000
A.
5000
Weight(g)
4000
Weight(g) = 0.004 * Length(cm )**3.2528 (n = 3078)
3000
2000
1000
0
10
20
30
40
50
60
70
80
Fork Length(cm )
6000 Males
- W eight(g) = 0.006 * Length(cm)**3.1414 (n = 854)
Females - W eight(g) = 0.0038 * Length(cm)**3.2678 (n = 2115)
5000
B. Weight(g)
4000
3000
2000
1000
0
10
20
30
40
50
Fork Length(cm )
118
60
70
80
Figure 102. Summer flounder maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1.0 99% matu rity
0.9
0.8
Probability of Maturity
0.7
0.6
0.5 50% matu rity
0.4
0.3
0.2
0.1
SEX
F M
0.0
10
20
30
40
50
Figure 47. Summer flounder diet in Chesapeake BayLe2002-2005 Total ngth (cm )combined.
Figure 103. Summer flounder diet in Chesapeake Bay 2002-2006 combined.
119
60
70
80
120
Figure 104. Weakfish minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
5 ,0 0 0 ,0 0 0
A. Minimum Trawlable Number
4 ,0 0 0 ,0 0 0
3 ,0 0 0 ,0 0 0
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
1 ,0 0 0 ,0 0 0
9 0 0 ,0 0 0
B.
Minimum Trawlable Biomass (kg)
8 0 0 ,0 0 0
7 0 0 ,0 0 0
6 0 0 ,0 0 0
5 0 0 ,0 0 0
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
121
M o n th Ye a r
122
March May
July
Figure 105. Site-specific weakfish abundance (number per hectare swept), 2002.
September November
123
March May July
Figure 106. Site-specific weakfish abundance (number per hectare swept), 2003.
September November
124
March May
July
Figure 107. Site-specific weakfish abundance (number per hectare swept), 2004.
September November
125
March May July
Figure 108. Site-specific weakfish abundance (number per hectare swept), 2005.
September November
126
March May July
Figure 109. Site-specific weakfish abundance (number per hectare swept), 2006.
September November
Figure 110. Weakfish length-frequency in Chesapeake Bay 2002-2006.
2002 140 120 100 80 60 40 20 0 0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
500
550
600
650
700
500
550
600
650
700
500
550
600
650
700
500
550
600
650
700
T o t a2l 0L0e3n g t h ( m m ) 300 200 100 0
Expanded Number
0
50
100
150
200
250
300
350
400
450
T o t a 2l 0L0e4n g t h ( m m ) 500 400 300 200 100 0 0
50
100
150
200
250
300
350
400
450
T o t a 2l 0L0e5n g t h ( m m ) 300 200 100 0 0
50
100
150
200
250
300
350
400
450
T o t a 2l 0L0e6n g t h ( m m ) 180 160 140 120 100 80 60 40 20 0 0
50
100
150
200
250
300
350
400
450
T o ta l L e n g th (m m )
127
Figure 111. Weakfish age-structure in Chesapeake Bay 2002-2006. 2002 700
629 600
519 500 400
291
300 200
132 100
62 9
3 6)
7)
99 (1
(1
6
5
4
3
(1
(1
99
99
8)
9) 99
0) 00 (2 2
0
1
(2
(2
00
00
2)
1)
0
A 2g0e 0( Y3e a r C l a s s ) 800
709 700
577
600 500
441
400 300 200
103 100
6
0
7)
8)
0
6
5
(1
(1
99
99
9) 4
3
(2
(1
00
99
0)
1) 00 (2 2
2A0g e0 (4Y e a r
C la s s )
1961
2000 1800 1600 1400 1200 1000
886
800 600
405
395
400 200
1
1200
6
4
5
(2
(1
(1
99
99
9)
0) 00
1) 3
1
2
(2
(2
(2
00
00
2)
3) 00
4) 00 (2 0
2A0g 0e 5( Y e a r
0 8)
0
0
C la s s )
1142
1100 1000 900 800
694
661
700 600 500 400 300
185
8
0
2A g0 e0 (6Y e a r
0
0)
1)
5
6
(2
(1
00
00 4
2
3
(2
(2
00
00 (2
(2 1
2)
4) 00
5) 00 (2 0
3)
0
9)
100
99
200
C la s s )
600 528
506
500 400 325
300 200 98
4
128
5
(2
(2
00
00
1)
2) 4
(2
00
00 (2 3
(2 2
(2 1
3)
4)
5) 00
6) 00 (2
00
A g e ( Y e a r C la s s )
0 0)
0
0
6
100
0
Expanded Number
0
1
(2
(2
00
00
2)
3)
0
Figure 112. Weakfish sex-ratios in Chesapeake Bay 2002-2005, by year (A), region (B), age (C).
n=
803
100
626
99.9
100.0
8.6
7.5
43.5
42.7
1108
1115
100.0
728
100.0
100.0
7.3
10.4
40.7
A.
90
38.0
37.0
Percent
Percent
80 70 60 55.9
50
54.7
52.6
49.8
47.8
Sex
F M U
Sex
F M U
40 30 20 10 0 2002
2003
2004
2005
2006
Year
n= 100
B. Percent
264
532
1830
99.9
100.1
99.9
100.0
20.4
20.9
16.5
4.9 39.2
4.8 41.7
47.0
35.9
90
1664
40.1
80
Percent
90 100.0
70 60 55.8
50 43.1
43.5
2 Md-Mid
3 Md-Low
40 30
53.5
32.6
20 10 0 1 Md-Upp
4 Va-Upp
5 Va-Low
Region
n=
Percent SUM
100
C.
1112
1170
964
231
34
9
3
100.0
100.1
100.0
100.0
100.0
100.0
100.0
24.5
40.6
44.5
55.4
61.9
33.3
66.7
90 80 33.0
Percent
70 66.7
60
59.2 55.4
50 40
Sex 44.6
42.5
38.1 33.3
30 20 10 0 0
1
2
3
4
AGE
129
5
6
F M U
Figure 113. Weakfish length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 3000
A.
2000 Weight(g)
We ig h t(g ) = 0 .0 0 5 6 * L e n g th (c m )**3 .1 6 6 2 (n = 4 4 5 9 )
1000
0 0
10
20
30
40
50
60
70
50
60
70
T o ta l L e n g th (c m )
3000 Males
- W eight(g) = 0.007 * Length(cm)**3.1006 (n = 1630)
Females - W eight(g) = 0.0053 * Length(cm)**3.1854 (n = 2355)
B. Weight(g)
2000
1000
0 0
10
20
30
40
T o ta l L e n g th (c m )
130
Figure 114. Weakfish maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1.0
99% matu r ity 0.9
0.8
Probability of Maturity
0.7
0.6
0.5
50% matu r ity 0.4
0.3
0.2
0.1
SEX
Figure 53. Weakfish diet in Chesapeake Bay 2002-2005 combined.
0.0 0
10
20
30
40
T o ta l L e n g th (c m )
Figure 115. Weakfish diet in Chesapeake Bay 2002-2006 combined.
131
50
60
F M 70
132
Figure 116. White perch minimum trawlable abundance estimates in numbers (A) and biomass (B) in Chesapeake Bay 2002-2006. R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M d -U p p
4 0 ,0 0 0 ,0 0 0
A. Minimum Trawlable Number
3 0 ,0 0 0 ,0 0 0
2 0 ,0 0 0 ,0 0 0
1 0 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
R e g io n
V a -L o w
V a -U p p
M d -L o w
M d - M id
M o n th Ye a r
M d -U p p
3 5 ,0 0 0 ,0 0 0
Minimum Trawlable Biomass (kg)
3 0 ,0 0 0 ,0 0 0
B.
6 ,0 0 0 ,0 0 0
5 ,0 0 0 ,0 0 0
4 ,0 0 0 ,0 0 0
3 ,0 0 0 ,0 0 0
2 ,0 0 0 ,0 0 0
1 ,0 0 0 ,0 0 0
0
M ar M ay Jul Sep Nov
M ar M ay Jul Sep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul S ep Nov
M ar M ay Jul Sep Nov
2002
2003
2004
2005
2006
133
M o n th Ye a r
134
March May
July
September
Figure 117. Figures 117. Site-specific white perch abundance (number per hectare swept), 2002.
November
135
March May
July
Figure 118. Site-specific white perch abundance (number per hectare swept), 2003.
September November
136
March May
July
Figure 119. Site-specific white perch abundance (number per hectare swept), 2004.
September November
137
March May
July
Figure 120. Site-specific white perch abundance (number per hectare swept), 2005.
September November
138
March May
July
Figure 121. Site-specific white perch abundance (number per hectare swept), 2006.
September November
Figure 122. White perch length-frequency in Chesapeake Bay 2002-2006.
2002 1200 1000 800 600 400 200 0 0
50
100
150
200
250
300
350
300
350
400
F o r k2 0L0e3n g t h ( m m ) 600 500 400 300 200 100 0
Expanded Number
0
50
100
150
200
250
400
Fork 2 0L0e4n g t h ( m m ) 1600 1400 1200 1000 800 600 400 200 0 0
50
100
150
200
250
300
350
400
300
350
400
F o r2k 0L0e5n g t h ( m m ) 1200 1000 800 600 400 200 0 0
50
100
150
200
250
F o r2k0 L0 e6 n g t h ( m m ) 2000 1500 1000 500 0 0
50
100
150
200
250
F o r k L e n g th (m m ) 139
300
350
400
140
A g e (Y e a r C la s s )
98
9)
28
(1
0)
16
15
14
(1
(1
(1
98
98
99
99
8)
9)
0)
1)
2)
16
15
14
13
12
(1
(1
(1
(1
(1
98
98
98
99
99
99
7)
8)
9)
0)
1)
2)
4
16
99
4
(1
1)
(1
99
(1
28
15
99
27
(1
2)
(1
11
4
14
99
538
(1
13
12
3)
16
13
3)
200
99
99
)
)
)
)
)
3)
94
95
96
97
99
9
9
(1
(1
(1
9
9
98
3
(1
(1
10
9
8
(1
(1
9
)
100
12
11
4)
)
)
0
4)
99
95
96
7
6
(1
99
)
)
0
99
(1
9
9
)
)
5
9
00
01
)
)
900
(1
5)
10
(1
(1
97
98
)
(1
0
0
02
03
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
(1
(1
(1
(1
(1
(1
98
98
98
98
99
99
)
)
)
)
)
)
)
)
)
)
6)
7)
8)
9)
0)
1)
2)
93
94
95
96
97
98
99
00
01
02
99
9
9
9
9
9
9
9
0
0
0
(1
(1
(1
(1
(1
(1
(1
(1
(2
(2
(2
1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0
11
99
924
(1
)
9
8
9
9
99
4
(2
(2
0
0
258
10
96
)
708
9
97
(1
(1
9
)
3
2
(2
(2
261
(1
9
)
700
(1
98
7
6
(1
00
)
)
1
0
700
9
8
9
)
600
(1
99
5
0
01
02
)
)
262
7
9
)
913
(1
00
(2
0
0
03
04
233
6
0
)
900
(2
01
4
(2
(2
0
0
400
5
0
)
800
(2
02
3
2
(2
(2
500
4
0
1000
(2
)
1
0
300
3
03
)
)
0
0
04
05
100
(2
0
0
4
2
(2
(2
0
1
0
Expanded Number Figure 123. White perch age-structure in Chesapeake Bay 2002-2005 (2006 ages not yet assigned). 2002
A g 2e 0( Y 0 e3a r C l a s s )
800 840
600 647
433
384
290
200
0 0
A2g 0 e 0( Y4e a r C l a s s )
3000
2000
1000
Ag 2 e0 (0Y 5e a r C l a s s )
824 925
616
722
500
517
400
300
91
196
2
0
Figure 124. White perch sex-ratios in Chesapeake Bay 2002-2005, by year (A), age (B).
n=
A.
100
551
177
356
419
100.0
100.0
99.9
100.0
100.0
28.9
31.2
20.5
24.8
31.8
90 80
79.3 74.9
70 Percent Percent
385
70.5
68.5
68.2
60 50
Sex
40
F M U
30 20 10 0 2002
2003
2004
2005
2006
Year
n=
Percent SUM
B.
100
6
33
95
79
118 114 219 132 136 248 72 103
100.1
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
5
12
23
42
24
28
19
27
31
30
31
68
8
8
2
100.0
100.0
100.0
100.0
100.0
8
15
100
100
100
84
90
92
34 85
80
81
76
76
70
73
72
70
70
69
Percent
60 58
55
50
Sex
40 30 20 10
11
0 0
1
2
3
4
5
6
7
8
AGE 141
9
10
11
12
13
14
15
F M U
Figure 125. White perch length-weight relationships in Chesapeake Bay 2002-2006 as calculated by power regression for sexes combined (A) and separately (B). 800
A.
700
600
W e ig h t(g ) = 0 .0 0 8 9 * L e n g th (c m )**3 .2 2 3 1 (n = 1 8 8 6 ) Weight(g)
500
400
300
200
100
0 0
10
20
30
40
F o r k L e n g th (c m )
800 Males
- W eight(g) = 0.0087 * Length(cm)**3.2227 (n = 464)
Females - W eight(g) = 0.0097 * Length(cm)**3.1949 (n = 1403)
700
600
B.
Weight(g)
500
400
300
200
100
0 0
10
20 F o r k L e n g th (c m )
142
30
40
Figure 126. White perch maturity schedule in Chesapeake Bay 2002-2006 combined, by sex. 1 .0
9 9 % m a tu r ity 0 .9
0 .8
Probability of Maturity
0 .7
0 .6
0 .5
5 0 % m a tu r ity 0 .4
0 .3
0 .2
0 .1
SEX
F M
0 .0 0
10
20
F o r k L e n g th (c m )
Figure 127. White perch diet in Chesapeake Bay 2002-2006 combined.
143
30
40
144
March
Figure 128. Surface temperature in Chesapeake Bay, 2002.
July
September November
145
March
Figure 129. Bottom temperature in Chesapeake Bay, 2002.
July
September November
146
March May
Figure 130. Surface temperature in Chesapeake Bay, 2003.
July
September November
147
March May
Figure 131. Bottom temperature in Chesapeake Bay, 2003.
July
September November
148
March May
Figure 132. Surface temperature in Chesapeake Bay, 2004.
July
September November
149
March May
Figure 133. Bottom temperature in Chesapeake Bay, 2004.
July
September November
150
March May
Figure 134. Surface temperature in Chesapeake Bay, 2005.
July
September November
151
March May
Figure 135. Bottom temperature in Chesapeake Bay, 2005.
July
September November
152
March May
Figure 136. Surface temperature in Chesapeake Bay, 2006.
July
September November
153
March May
Figure 137. Bottom temperature in Chesapeake Bay, 2006.
July
September November
154
March
Figure 138. Surface salinity in Chesapeake Bay, 2002.
July
September November
155
March
Figure 139. Bottom salinity in Chesapeake Bay, 2002.
July
September November
156
March May
Figure 140. Surface salinity in Chesapeake Bay, 2003.
July
September November
157
March May
Figure 141. Bottom salinity in Chesapeake Bay, 2003.
July
September November
158
March May
Figure 142. Surface salinity in Chesapeake Bay, 2004.
July
September November
159
March May
Figure 143. Bottom salinity in Chesapeake Bay, 2004.
July
September November
160
March May
Figure 144. Surface salinity in Chesapeake Bay, 2005.
July
September November
161
March May
Figure 145. Bottom salinity in Chesapeake Bay, 2005.
July
September November
162
March May
Figure 146. Surface salinity in Chesapeake Bay, 2006.
July
September November
163
March May
Figure 147. Bottom salinity in Chesapeake Bay, 2006.
July
September November
164
March July
Figure 148. Surface dissolved oxygen in Chesapeake Bay, 2002.
September November
165
March July
Figure 149. Bottom dissolved oxygen in Chesapeake Bay, 2002.
September November
166
March May July
Figure 150. Surface dissolved oxygen in Chesapeake Bay, 2003.
September November
167
March May
July
Figure 151. Bottom dissolved oxygen in Chesapeake Bay, 2003.
September November
168
March May
July
Figure 152. Surface dissolved oxygen in Chesapeake Bay, 2004.
September November
169
March May
July
Figure 153. Bottom dissolved oxygen in Chesapeake Bay, 2004.
September November
170
March May
July
Figure 154. Surface dissolved oxygen in Chesapeake Bay, 2005.
September November
171
March May
July
Figure 155. Bottom dissolved oxygen in Chesapeake Bay, 2005.
September November
172
March May
July
Figure 156. Surface dissolved oxygen in Chesapeake Bay, 2006.
September November
173
March May
July
Figure 157. Bottom dissolved oxygen in Chesapeake Bay, 2006.
September November