Catch Efficiencies of a 6.1-Meter Otter Trawl for Estuarine Fish Populations

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Abstract
Gear catch efficiencies, q, are useful in achieving more accurate estimates of fish abundance. Twenty mark‐recapture experiments using juveniles (50‐80 mm) and yearling (90‐140 mm) pinfish, Lagodon rhomboides, and spot, Leiostomus xanthurus, were conducted in an enclosed 5‐hectare North Carolina estuarine embayment to estimate the catch efficiencies for a 6.1‐m otter trawl. Catch efficiencies, defined as the percentage of fish in the path of the trawl that are captured, were calculated from the ratio of the average trawl estimate of marked fish density to the known density of marked fish. The trawl was towed at approximately 1.6 knots and sampled a path 5 m wide. Estimated catch efficiencies for the trawl during daylight were: juvenile pinfish 48%; yearling pinfish 49%; juvenile spot 32%; and yearling spot 32%. Precision for the efficiencies was relatively low with the standard error ranging between 9 and 58% of the mean. Catch efficiencies did not differ between day versus night recovery or appear to be related to fish density. Relative catch efficiencies for the 6.1‐m trawl were greater than those for a 3.0‐m and a 4.6‐m otter trawl.

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