Evaluation of a sorting grid bycatch reduction device for the selective flatfish bottom trawl in the U.S. West Coast fishery

Published source details Lomeli M.J.M. & Wakefield W.W. (2016) Evaluation of a sorting grid bycatch reduction device for the selective flatfish bottom trawl in the U.S. West Coast fishery. Fisheries Research, 183, 294-303.
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This study is summarised as evidence for the following.

	Action	Category
	Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net Action Link

Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net

A replicated study in 2014 of an area of seabed in the Pacific Ocean off Oregon, USA (Lomeli & Wakefield 2016) found that a flexible size-sorting escape grid system fitted to a bottom fish trawl net reduced the catches of non-target fish species, and typically retained much of the targeted flatfish catch. Data were not tested for statistical significance. Overall, catches of five groups and species of non-target roundfish and one flatfish (see paper for list of species), relative to the catches retained in the codend, were reduced by 64–99% (grid: 99–5,372 kg, codend: 16–95 kg), and the probability of escape increased with increasing length. For five target flatfish species evaluated, escape rates were 8–32% (grid: 28–1,164 kg, codend: 268–7,089 kg). In June 2014, a total of 38 trawl deployments were completed west of central Oregon. Hauls were 1 h at an average depth of 174 m. A flexible grid system was fitted to a bottom trawl net, consisting of a four-seam tube of netting inserted in front of the codend (see paper for specifications). The two side panels had 5 x 22 cm grid openings to either exclude fish from the trawl via an exit opening or allow fish to pass through to the codend. A cover net attached over the grid opening sampled escaping fish. All fish caught in the cover net and codend were identified and weighed, and fish lengths sub-sampled.

(Summarised by: Natasha Taylor)