Circle hook effectiveness for the mitigation of sea turtle bycatch and capture of target species in a Brazilian pelagic longline fishery

Published source details Sales G., Giffoni B.B., Fiedler F.N., Azevedo V.N.G., Kotas J.E., Swimmere Y. & Bugoni L. (2010) Circle hook effectiveness for the mitigation of sea turtle bycatch and capture of target species in a Brazilian pelagic longline fishery. Aquatic Conservation: Marine and Freshwater Ecosystems, 20.
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This study is summarised as evidence for the following.

	Action	Category
	Use circle hooks instead of J-hooks Action Link

Use circle hooks instead of J-hooks

A replicated, controlled study in 2004–2008 in pelagic waters in the south-western Atlantic Ocean in Brazil (Sales et al. 2010) found that using circle hooks reduced unwanted catch of sea turtles compared to J-hooks in a longline fishery. Unwanted catch of loggerhead Caretta caretta and leatherback Dermochelys coriacea were reduced when circle hooks were used (loggerhead: 0.8 turtles/1,000 hooks, leatherback: 0.7) compared to J-hooks (loggerhead: 1.9, leatherback: 1.6). Fewer loggerhead turtles swallowed hooks when circle hooks were used (6%) compared to J-hooks (25%). However, on average, circle hooks caught larger loggerheads (61 cm average carapace length) than J-hooks (58 cm). Catch rates of most target fish species was increased when circle hooks were used, with the exception of swordfish Xiphius gladius (see paper for details). Catch rates of 10° offset 18/0 circle hooks (2.8–2.2 cm gape width) were compared to traditional 9/0 0° offset J-hooks (2.9 cm gape width). Twenty-seven trips totalling 229 fishing trips were undertaken. A total of 145,828 baited hooks were tested by alternating hooks along sections of the mainline.

(Summarised by: Maggie Watson, Katie Sainsbury)