A trap with a twist: evaluating a bycatch reduction device to prevent rockfish capture in crustacean traps

Published source details Favaro B., Duff S.D. & Côté I.M. (2013) A trap with a twist: evaluating a bycatch reduction device to prevent rockfish capture in crustacean traps. ICES Journal of Marine Science, 70, 114-122.
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This study is summarised as evidence for the following.

	Action	Category
	Modify fishing trap/pot configuration Action Link

Modify fishing trap/pot configuration

A replicated, randomized, controlled study in 2010 in two areas of seabed in the Strait of Georgia, in the Pacific Ocean, British Columbia, Canada (Favaro et al. 2013) found that two of five modified designs of traps commercially targeting spot prawns Pandalus platyceros caught fewer unwanted fish and protected rockfish Sebastes spp. compared to a conventional unmodified trap. Overall, unwanted fish catches were 69% and 68% lower in the five and seven-ring tunnel-equipped traps than the conventional traps respectively, but unwanted fish catch rates in the three other modified trap designs were similar to the conventional trap (data presented graphically – see original paper). Only six rockfish were caught overall: none in tunnel-equipped traps, one in the 6.4 cm entrance trap, two in the 7.0 cm entrance trap and three in the unmodified trap. In addition, average rockfish body weight and length were lower in traps with a five-ring tunnel and both five and seven-ring tunnel entrances respectively, compared to other designs (data reported as statistical model results). In addition, all modified traps caught fewer and generally smaller commercial target prawns than conventional traps (data reported as statistical model results). Traps were randomly ordered in groups of 10 along single weighted lines at 50–120 m depths. All traps were truncated cone designs with 3.8 cm mesh. Conventional traps (7.6 cm single-ring entrances) were compared to five modified designs with either a reduced diameter entrance (7.0 cm or 6.4 cm), or a tunnel-design 7.6 cm entrance of four, five or seven rings (see original paper for gear specifications).

(Summarised by: Leo Clarke)