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Brandon Muffley and Alexei Sharov MD Dept. of Natural Resources, Fisheries Service Annapolis, MD

Design and Implementation of a Fishery-Independent Shallow Water Trawl Survey for Maryland’s Portion of Chesapeake Bay. Brandon Muffley and Alexei Sharov MD Dept. of Natural Resources, Fisheries Service Annapolis, MD. Background. Why needed ?.

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Brandon Muffley and Alexei Sharov MD Dept. of Natural Resources, Fisheries Service Annapolis, MD

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  1. Design and Implementation of a Fishery-Independent Shallow Water Trawl Survey for Maryland’s Portion of Chesapeake Bay Brandon Muffley and Alexei Sharov MD Dept. of Natural Resources, Fisheries Service Annapolis, MD

  2. Background • Why needed ? • Chesapeake 2000 commitment to multispecies approaches • Past/current studies lack spatial and temporal coverage needed • Few studies incorporate shoal (shallow) areas • Wide range of information gained on a variety of economically & ecologically important species • ChesFIMS survey • Broad scale survey – mid-water trawls in mainstem of C. B. • Shoal survey – bottom trawl in shallow waters of MD C. B.

  3. S4 S1 Solomons S2 Solomons S3 Shoal Survey Design 2001 4 Strata 108 Stations 3 Sampling Periods 6 minute trawls Surveys conducted in four mid-Bay strata, chosen for compatibility with broad scale efforts, and with existing surveys • Stratified random design • Proportional station allocation • Trawl design from MD DNR crab survey

  4. Shoal Survey Design (con.t) 2002 9 Strata 120 Stations 3 Sampling Periods 6 minute trawls S9 S7 Annapolis S6 S8 Surveys conducted in nine mid & upper Bay strata, chosen for compatibility with broad scale efforts, and with existing surveys S5 • Stratified random design • Proportional station allocation • based on variance estimates

  5. Data Collection • Biological Information • Species ID • Length (TL) • Weight • Sex (blue crab) • Gut content • Water Quality • Temperature • DO • Salinity • Depth • Secchi • Misc. Information • Tide State • Bottom Substrate • Boat Speed/RPM • Position Coordinates • Air Temp.

  6. Summary Statistics

  7. Species Caught July 2002 American Eel Northern Searobin Atlantic Silverside Oyster Toadfish Bay Anchovy Pigfish Blackcheek Tonguefish Silver Perch Blue Crab Skilletfish Croaker Spot Harvestfish Spotted Seatrout Hogchoker Striped Bass Horseshoe Crab Summer Flounder Lizardfish Weakfish Naked Goby White Perch Northern Kingfish Windowpane Flounder Northern Pipefish Winter Flounder Northern Puffer

  8. 2001 Total N 2002 Total N Solomons Solomons Yearly Distribution of Abundance

  9. 2001 2002 Total g Total g Solomons Solomons Yearly Distribution of Biomass

  10. Overall Catch Tow -1 by Species July 2001 September 2001 Bay Anchovy Blue Crab White Perch Croaker Spot Striped Bass Hogchoker Summer Flounder Weakfish Lizardfish N. Kingfish Other

  11. Overall Biomass Tow –1 by Species July 2001 September 2001 Bay Anchovy Blue Crab White Perch Croaker Spot Striped Bass Hogchoker Summer Flounder Weakfish Lizardfish N. Kingfish Other

  12. Abundance Trends Tangier Sound – Blue Crab • MD DNR crab trawl surveyChesFIMS shoal survey • Fixed stations * Stratified random stations • Few stations * Numerous stations • 16’ semiballoon otter trawl * 16’ semiballoon otter trawl • 6 minute tows * 6 minute tows • 5 different strata sampled by both surveys

  13. Biological Characteristics Bay Anchovy Mean Length (mm) May 67.2 • Size and size-at-age • Growth rates • Habitat Preferences/Associations • (adults & juveniles) • Recruitment * For a number of species

  14. Biological Characteristics Bay Anchovy Mean Length (mm) May 67.2 July 43.9 • Size and size-at-age • Growth rates • Habitat Preferences/Associations • (adults & juveniles) • Recruitment * For a number of species

  15. Biological Characteristics Bay Anchovy Mean Length (mm) May 67.2 July 43.9 Sept 48.1 • Size and size-at-age • Growth rates • Habitat Preferences/Associations • (adults & juveniles) • Recruitment * For a number of species

  16. 22 September 2002 13 9 25 18 8 11 11 6 6 Species Diversity By Strata Species Diversity vs. Species Richness

  17. Species Diversity All 2001 22 22 22 By Season Species Diversity vs. Species Richness

  18. 19 15 July 01 & 02 16 27 15 22 8 11 7 2 Species Diversity By Year Species Diversity vs. Species Richness

  19. 100 90 80 -1 70 60 50 mean Catch tow 40 30 20 10 0 Deep Stations Shallow Day Trawls Night Trawls Overall (8m) Stations (4m) Gear Comparison Study Why needed: * Allow both surveys to be combined * Estimate small scale spatial and temporal covariation * Different sampling scheme * Different gear – fishing efficiencies

  20. Diet Analysis Species Collected Croaker Spot Weakfish Hogchoker Striped bass White perch Northern Kingfish A. Silverside Trophic Linkages Predator – prey Multispecies models Bioenergetic models

  21. Sample Diets • Gut contents flushed, sample split, taxa identified, • weighed and counted (from Miller et. al. 2001) 0.4 0.00 0.67 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.00 0.04 0.00 0.04 0.04 0.00 0.00 0.04 0.00 0.00 0.08 0.00 0.00 0.04 0.00 0.00 0.00 0.08 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.46 0.00 0.00 0.3 Striped Bass - Upper Bay (n = 24) 0.2 Percent Weight (% W) 0.1 0 Egg Bivalve Fish Crab Mysid Insect Isopod Diptera Mussel Shrimp Annelid Fish Egg Worm Tunicate Fish Part Blue Crab Copepod Clupeid Egg Barnacle Flatworm Polychaete Nematode Amphipod Insect Egg Cumacean Nemertean Gastropod Insect Larvae Grass Shrimp Chironomidae Nudibranch Unidentified Razor Clam Unidentified Tube Worm Organic Matter Copepod Egg Gastropod Egg Gnathostomulid Skeleton Unidentified Unidentified Unidentified Unidentified Unidentified Unidentified Prey Item

  22. Summary • Information Gained: • Survey design and implementation • CPUE and Biomass estimates • Species abundance and distribution • Life history characteristics (i.e. growth and habitat use) • Species diversity and richness • Recruitment • Trophic linkages – gut analysis • Time series of abundance • Management Implications Spatially & Temporally extensive Species rich • Other Areas of Interest: • Water quality • Trawl time • Volumetric analysis / gear comparison

  23. Acknowledgements • Project funded by CBSAC through NOAA CB Office • Nate Herman • Tom Miller • Jon Volstad • Phil Jones • Dale Weinrich • Paul Genovese • Harry Rickabaugh • Keith Witeford • Mark Matsche • Tony Jarzynski • Jim Mower • Bob Sadzinski • Marek Topolski • Harley Speir • Harry Hornick • Butch Webb • Bruce Pyle • Jim Thompson • Kinte Thompson • Kevin Donaldson • Bennie Williams • Jen Ball • Matapeake interns

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