Effectiveness of bycatch-reduction devices in roller-frame trawls used in the Florida shrimp fishery

Published source details Crawford C.R., Steele P., McMillen-Jackson A.L. & Bert T.M. (2011) Effectiveness of bycatch-reduction devices in roller-frame trawls used in the Florida shrimp fishery. Fisheries Research, 108, 248-257.
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This study is summarised as evidence for the following.

	Action	Category
	Fit large, supported escape openings (such as Fisheyes, Bigeyes and radial escape sections) to trawl nets Action Link

Fit large, supported escape openings (such as Fisheyes, Bigeyes and radial escape sections) to trawl nets

A replicated, paired, controlled study in 1997–1999 of two coastal seabed areas in the Atlantic Ocean off Florida, USA (Crawford et al. 2011) found that large, supported escape openings (four designs) fitted to a shrimp roller-frame trawl net reduced the overall unwanted catch of finfish in three of four cases compared to a standard net without escape openings. Across all trials, average catch weights (and numbers, see paper for data) of all non-target finfish were lower in nets with an extended-mesh funnel design of escape opening, both with and without a stimulator cone (funnel: 20–206 g/effort, standard: 53–309 g/effort) and in nets with a Florida Fisheye design and stimulator cone (Fisheye/cone: 107 g/effort, standard: 275 g/effort), compared to standard nets. Total finfish catch rates in nets with just a Florida Fisheye (no stimulator cone) were similar to standard nets (Fisheye/ no cone: 112–230 g/effort, standard: 111–248 g/effort), however, the effect varied between individual fish species (see paper for data). Data were collected from 158 paired trawl deployments targeting pink shrimp Farfantepenaeus duorarum in two areas: at Tarpon Springs in October 1997 and March and October 1998 (research vessel), and at Biscayne Bay in November/December 1999 (commercial vessel). One trawl net equipped with one of two escape opening designs (large-mesh extended-mesh funnel or Florida Fisheye), with and without a stimulator cone (nylon webbing designed to prevent finfish from reaching the codend), was towed on one side of each vessel. On the other side a standard net was towed at the same time. Finfish in the catches were sorted by species and weighed.

(Summarised by: Khatija Alliji)