Reduction of Flatfish Bycatch in the Small-Mesh....
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GRANT NUMBER:  NA46FD0325          NMFS NUMBER:  93-NER-015

REPORT TITLE: Reduction of Flatfish Bycatch in the Small-Mesh Bottom Trawls Used in the New England Whiting Fishery: An Investigation of Fish Behavior and an Evaluation of Separator Trawl Technologies

AUTHOR: Joseph DeAlteris

PUBLISH DATE:  July 10, 2001

AVAILABLE FROM:  National Marine Fisheries Service, Northeast Region, One Blackburn Drive, Gloucester, MA 01930-2298.  PHONE: (978) 281-9267


Experiments were conducted to evaluate two different strategies for the reduction of flatfish bycatch in the small-mesh groundfish bottom trawl. The first set of experiments was devoted to modifications of the fishing line and sweep. Vertical openings of varying height separating the fishing line from the sweep were evaluated, as were discontinuities in the bosum of the sweep. Of the four modifications tested, only one experimental trawl with a 2.1-m long by 0.3-m high discontinuity in the sweep resulted in significant reductions in flatfish bycatch (96% on average) while not affecting catch of target fish. The second set of experiments was directed at modifications that included an escape panel in the lower belly. The escape panels were designed with openings of different sizes and twines (color and diameter). Of the four modifications tested, again only one experimental trawl with 40.6-cm diamond-shaped meshes constructed with 1.6-mm diameter orange-colored twine proved effective in significantly reducing the flatfish bycatch (73%) while not affecting the catch of the target species. Both strategies are simple and could be easily incorporated into similar small mesh bottom trawl fisheries in New England.

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