Dataset: Groundfish Trawl Nets Designed to Reduce the Bycatch of Cod: catch data from Fishing Vessels NEC-MP2000-2 in the Gulf of Maine from 2000-2002 (NEC-CoopRes project)

Testing of two experimental trawl nets established that catch rates of Atlantic cod Gadus morhua could be reduced from standard practices while allowing the targeting of flatfish Pleuronectidae. The Ribas and topless nets both modify the top half of a trawl net; the Ribas net by using large square mesh; the topless net by removing much of the twine in the top of the net. Seventy pairs of alternate tows showed reductions of cod catch rates (kg/hr) that exceeded 76% for both nets. Catch rates of sublegal (<33 cm TL) yellowtail flounder Limanda ferruginea were more than 74% lower for both nets, compared to standard flatfish trawl. Reductions of sublegal (<33 cm) catch rates for winter flounder Pseudopleuronectes americanus exceeded 61%. Significant reductions occurred in legal catch for yellowtail (>32%) and winter flounders (>44%) with some evidence that this reduction was lower for the topless trawl. Underwater video showed cod exiting the nets through the top mesh and through the gap made by the removal of twine.
(from abstract, final report)