73 research outputs found

    Fish assemblages found in tidal-creek and seagrass habitats in the Suwannee River estuary

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    Fish assemblages were investigated in tidal-creek and seagrass habitats in the Suwannee River estuary, Florida. A total of 91,571 fish representing 43 families were collected in monthly seine samples from January 1997 to December 1999. Tidal creeks supported greater densities of fish (3.89 fish/m2; 83% of total) than did seagrass habitats (0.93 fish/m2). We identified three distinct fish assemblages in each habitat: winter−spring, summer, and fall. Pinfish (Lagodon rhomboides), pigfish (Orthopristis chrysoptera), and syngnathids characterized seagrass assemblages, whereas spot (Leiostomus xanthurus), bay anchovy (Anchoa mitchilli), silversides (Menidia spp.), mojarras (Eucinostomus spp.), and fundulids characterized tidal-creek habitats. Important recreational and commercial species such as striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) were found primarily in tidal creeks and were among the top 13 taxa in the fish assemblages found in the tidal-creek habitats. Tidal-creek and seagrass habitats in the Suwannee River estuary were found to support diverse fish assemblages. Seasonal patterns in occurrence, which were found to be associated with recruitment of early-life-history stages, were observed for many of the fish species

    Estimating Relative Abundance of Young of Year American Eel, Anguilla rostrata, in the Virginia Tributaries of Chesapeake Bay (Spring 2007)

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    The Atlantic States Marine Fisheries Commission (ASMFC) adopted the Interstate Fishery Management Plan (FMP) for the American eel in November 1999. The FMP focuses on increasing coastal states’ efforts to collect American eel data through both fishery dependent and fishery independent studies. Consequently, member jurisdictions (including Virginia) agreed to implement an annual survey for YOY American eels. The survey is intended to “…characterize trends in annual recruitment of the YOY eels over time [to produce a] qualitative appraisal of the annual recruitment of American eel to the U.S. Atlantic Coast” (ASMFC, 2000). The development of these surveys began in 2000 with full implementation by 2001. Survey results should provide necessary data on coastal recruitment success and further understanding of American eel population dynamics. A recent American eel stock assessment report (ASMFC, 2006) emphasized the importance of the coast-wide survey as an index of sustained recruitment over the historical coastal range and an early warning of potential range 4 contraction of the species. The Virginia Institute of Marine Science continued its spring sampling to estimate relative abundance of young of year (YOY) American eels in Virginia tributaries of Chesapeake Bay. Funding was provided by the Marine Recreational Fishing Advisory and Commercial Fishing Advisory Boards, which ensured compliance with the 1999 ASMFC Interstate Fishery Management Plan for American Eel

    Variability in juvenile growth, mortality, maturity, and abundance of American shad and blueback herring in Virginia

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    Young-of-year (YOY) population dynamics of American shad and blueback herring in Virginia\u27s rivers were examined with an emphasis on variability in growth and mortality rates. In addition, an analysis was conducted to relate juvenile abundance indices of American shad to adult indices to establish a stock-recruitment relationship. to accomplish the stock recruitment relationship, an additional study that examined maturation schedules and inter-annual variability in maturation schedules among stocks was performed. Results of population dynamics studies found that growth and mortality rates of American shad and blueback herring varied by river and year and that conspecific abundance was an important factor in predicting size at the end of summer indicating density-dependent regulation of growth. For both species, instantaneous growth was highest at 40 d and decreased by 100 d as water temperatures decreased each year. American shad Mortality rates increased from 2005 to 2007 with highest rates observed in the James River, while mortality rates for blueback herring had no clear pattern. Large year-classes of Alosa spp. that are smaller in size prior to emigration into the coastal ocean may experience higher mortality rates resulting in recruitment stabilization. Despite the close proximity of four river systems studied, there were persistent differences in growth and mortality rates that support observed trends in year-class strength. High mortality rates observed in the James River support the observation of almost complete recruitment failure of wild American shad in this system. Furthermore, low mortality rates observed in the Rappahannock River are consistent with an increasing trend in recruitment of maturing females, while lower mortality rates and similar growth rates observed in the Mattaponi River compared with the Pamunkey River support long term observations of greater juvenile production of American shad in the Mattaponi River. Young-of-year blueback herring recruitment in Virginia rivers was an episodic process with multiple peaks observed throughout summer indicating that cohorts were not fully vulnerable to sampling and that there may be movement out of adjacent habitats. Maturation of American shad showed consistent patterns with most American shad mature by age 5. However, year-class specific estimates ranged from 50% to 85% mature in the James River, from 59% to 79% in the Rappahannock River, and from 60% to 87% in the York River. Based on current monitoring, the age of full recruitment to the staked gillnet fishery is age 5, corresponding to the age when the largest proportion of the population reaches maturity. Harvest of age 5 females in the historical fishery was probably a contributing factor to its collapse during the 1980s. Persistent differences in maturity schedules of American shad between the James and York rivers, and to a lesser extent with those from the Rappahannock River, show that neighboring stocks that experience similar climate regimes can have stock-specific maturity patterns that persist through time. Using juvenile abundance indices (or hatchery release in the case of the James River), the estimated maturity schedule, and estimated adult mortality rates, resulted in a predicted index that matched observed trends from 1998 to 2006 for three stocks of American shad. This study demonstrates that population dynamics of juvenile Alosa spp. is highly variable in a temporal and spatial context involving density-dependent processes that act to regulate year class production

    Evaluating Recruitment of American Eel, Anguilla rostrata, to the Potomac River (Spring 2008)

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    The Atlantic States Marine Fisheries Commission (ASMFC) adopted the Interstate Fishery Management Plan (FMP) for the American eel in November 1999. The FMP focuses on increasing coastal states’ efforts to collect American eel data through both fishery-dependent and fishery-independent studies. Consequently, member jurisdictions agreed to implement an annual survey for young of the year (YOY) American eels. The survey is intended to “…characterize trends in annual recruitment of the YOY eels over time [to produce a] qualitative appraisal of the annual recruitment of American eel to the U.S. Atlantic Coast” (ASMFC, 2000). The development of these surveys began in 2000 with full implementation by 2001. Survey results should provide necessary data on coastal recruitment success and further understanding of American eel population dynamics. A recent American eel stock assessment report (ASMFC, 3 2006) emphasized the importance of the coast-wide survey as an index of sustained recruitment over the historical coastal range and an early warning of potential range contraction of the species. The Virginia Institute of Marine Science continued its spring sampling to estimate relative abundance of YOY American eels in the Potomac River. Funding was provided by the Potomac River Fisheries Commission, which ensured compliance with the 1999 ASMFC Interstate Fishery Management Plan for American Eels

    Evaluating Recruitment of American Eel, Anguilla rostrata, in the Potomac River (Spring 2009)

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    The Atlantic States Marine Fisheries Commission (ASMFC) adopted the Interstate Fishery Management Plan (FMP) for the American eel in November 1999. The FMP focuses on increasing coastal states’ efforts to collect American eel data through both fishery-dependent and fishery-independent studies. Consequently, member jurisdictions agreed to implement an annual survey for young of year (YOY) American eels. The survey is intended to “…characterize trends in annual recruitment of the YOY eels over time [to produce a] qualitative appraisal of the annual recruitment of American eel to the U.S. Atlantic Coast” (ASMFC 2000). The development of these surveys began in 2000 with full implementation by 2001. Survey results should provide necessary data on coastal recruitment success and further understanding of American eel 3 population dynamics. A recent American eel stock assessment report (ASMFC 2006) emphasized the importance of the coast-wide survey for providing data useful in calculating an index of recruitment over the historical coastal range and for serving as an early warning of potential range contraction of the species. Funding for the Virginia Institute of Marine Science’s spring survey in the Potomac River was provided by the Potomac River Fisheries Commission, thereby ensuring compliance with the 1999 ASMFC Interstate Fishery Management Plan for American Eels

    2019 Annual Report Estimating Relative Juvenile Abundance of Ecologically Important Finfish in the Virginia Portion of Chesapeake Bay (1 July 2018 – 30 June 2019)

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    EXECUTIVE SUMMARY The Trawl Survey provides crucial data to state, regional, and national fisheries management agencies, including the Virginia Marine Resources Commission (VMRC), the Atlantic States Marine Fisheries Commission (ASMFC), the Mid-Atlantic Fisheries Management Council (MAFMC), and the National Marine Fisheries Service (NMFS). The MAFMC recognizes the juvenile trawl survey as one of the key predictors of Summer Flounder recruitment. Annual indices of juvenile abundance have been generated from trawl survey data for species of key recreational and ecological importance in the Virginia portion of Chesapeake Bay. These include Spot, Atlantic Croaker, Weakfish, Summer Flounder, Black Sea Bass, Scup, Striped Bass, White Perch, White Catfish, Channel Catfish, Blue Catfish, Silver Perch, American Eel, and Bay Anchovy. We completed 1,224 tows in 2018–2019. We collected 660,907 fishes and Bay Anchovy continue to be the most abundant species observed in the survey, accounting for 58% of all fishes collected. Of the target species for which we provide indices of relative abundance, 10 species categories (considering YOY and Age 1+ as distinct categories) exhibited below-average abundance in 2018 – 2019 (American Eel [all three rivers], Bay Anchovy, Black Sea Bass, Blue Catfish age 1+ [Rappahannock River], Channel Catfish juveniles and age 1+ [all three rivers], Scup, Weakfish, White Catfish juveniles [York and Rappahannock rivers], and White Catfish age 1+ [all three rivers]). Seven species categories exhibited above-average abundances (Blue Catfish juveniles [all three rivers], Blue Catfish age 1+ [James and York rivers], Silver Perch, Striped Bass, White Catfish juveniles [James River], White Perch juveniles [James and Rappahannock rivers], and White Perch age 1+ [James River]). Juvenile Atlantic Croaker, Spot, Summer Flounder, and White Perch [York River], as well as age 1+ White Perch [York and Rappahannock rivers] exhibited average relative abundance in 2018-2019. In 2018, we observed the second lowest level of recruitment for Black Sea Bass and the highest recruitment of Blue Catfish juveniles in the James River, and the second highest levels in the York and Rappahannock rivers. Striped Bass juveniles showed strong recruitment this year and Silver Perch continued to exhibit above-average recruitment, whereas Weakfish had below-average recruitment for the fifth year in a row

    2022 Annual Report - Estimating Relative Juvenile Abundance of Ecologically Important Finfish in the Virginia Portion of Chesapeake Bay (1 July 2021 – 30 June 2022)

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    The Trawl Survey provides crucial data to state, regional, and national fisheries management agencies, including the Virginia Marine Resources Commission (VMRC), the Atlantic States Marine Fisheries Commission (ASMFC), the Mid‐Atlantic Fisheries Management Council (MAFMC), and the National Marine Fisheries Service (NMFS). The MAFMC recognizes the juvenile trawl survey as one of the key predictors of Summer Flounder recruitment. Annual indices of juvenile abundance have been generated from trawl survey data for species of key recreational and ecological importance in the Virginia portion of Chesapeake Bay. These include Spot, Atlantic Croaker, Weakfish, Summer Flounder, Black Sea Bass, Scup, Striped Bass, White Perch, White Catfish, Channel Catfish, Blue Catfish, Silver Perch, American Eel, and Bay Anchovy. We completed all planned tows (1,224) from July 2021 to June 2022 and collected 478,313 fishes. Bay Anchovy continue to be the most abundant species observed in the survey, accounting for 58% of all fishes collected. Of the 36 target species categories for which we provide indices of relative abundance, 29 species categories (considering YOY and age 1+ as distinct categories) exhibited below‐average abundance in 2021 – 2022. Five species categories exhibited average abundances including Atlantic Croaker, Black Sea Bass, White Perch YOY (York River) and age 1+ White Perch (Rappahannock and York rivers). Only age 1+ Blue Catfish (York and James rivers exhibited above‐average abundances in 2021‐2022

    Evaluating Recruitment of American Eel, Anguilla rostrata, in the Potomac River (Spring 2012)

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    The Atlantic States Marine Fisheries Commission (ASMFC) adopted the Interstate Fishery Management Plan (FMP) for the American eel in November 1999. The FMP focuses on increasing coastal states’ efforts to collect American eel data through both fishery-dependent and fishery-independent studies. Consequently, member jurisdictions agreed to implement an annual survey for young-of-year (YOY) American eels. The survey is intended to “…characterize trends in annual recruitment of the YOY eels over time [to produce a] qualitative appraisal of the annual recruitment of American eel to the U.S. Atlantic Coast” (ASMFC 2000). The development of these surveys began in 2000 with full implementation by 2001. Survey results should provide necessary data on 4 coastal recruitment success and further understanding of American eel population dynamics. A recent American eel stock assessment report (ASMFC 2009) emphasized the importance of the coast-wide survey for providing data useful in calculating an index of recruitment over the historical coastal range and for serving as an early warning of potential range contraction of the species. Funding for the Virginia Institute of Marine Science’s spring survey in the Potomac River was provided by the Potomac River Fisheries Commission, thereby ensuring compliance with the 1999 ASMFC Interstate Fishery Management Plan for American Eels
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