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Estimation of Bottom Trawl Catch Efficiency for Two Demersal Fishes, Atlantic Croaker and White Perch in Chesapeake Bay
Citation:
HOFFMAN, J., C. F. BONZEK, AND J. LATOURRETTE. Estimation of Bottom Trawl Catch Efficiency for Two Demersal Fishes, Atlantic Croaker and White Perch in Chesapeake Bay. Marine and Coastal Fisheries. American Fisheries Society, Bethesda, MD, 1(1):255-269, (2009).
Impact/Purpose:
The manuscript presents an in situ analysis of demersal trawl performance in a shallow, coastal ecosystem – a habitat that presents many difficulties for fisheries assessment yet is critical to assess.
Description:
We present an efficiency analysis of a fisheries-independent demersal trawl survey in Chesapeake Bay, the largest estuary in the United States, that is presently being used for multi-species fisheries assessment and management. The manuscript presents an in situ analysis of demersal trawl performance in a shallow, coastal ecosystem – a habitat that presents many difficulties for fisheries assessment yet is critical to assess. We were able to observe reduced efficiency and quantitatively relate it to factors widely understood to effect avoidance behavior (fish density, trawl width) and to some that are not as well known (sediment type, bottom depth). Further, we were able to obtain sufficient data to use in situ measures of target strength to develop a total length-target strength relationship (TL-TS) for Atlantic croaker. The results from this analysis seem to point to an important factor for scaling echo-integration – the systematic reduction in TS-at-length owing to tilting behavior in fish. We conclude that the trawl survey data alone may be used to generate a population index, but, owing to the variable gear efficiency, should be integrated with hydroacoustics to obtain unbiased population estimates for Chesapeake Bay ecosystem management. This abstract does not necessarily reflect USEPA policy.
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Estimation of Bottom Trawl Catch Efficiency for Two Demersal Fishes, Atlantic Croaker and White Perch in Chesapeake Bay