Two devices for mitigating odontocete bycatch and depredation at the hook in tropical pelagic longline fisheries

Published source details Hamer D.J., Childerhouse S.J., McKinlay J.P., Double M.C. & Gales N.J. (2015) Two devices for mitigating odontocete bycatch and depredation at the hook in tropical pelagic longline fisheries. ICES Journal of Marine Science, 72, 1691-1705.
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This study is summarised as evidence for the following.

	Action	Category
	Use catch and hook protection devices on fishing gear Action Link

Use catch and hook protection devices on fishing gear

A controlled study in 2010–2013 of two pelagic areas in the South Pacific Ocean, Australia, and Fiji (Hamer et al. 2015) reported that using cage or chain devices on fishing hooks resulted in fewer catches of toothed whales (Odontoceti) and fewer whale-damaged fish. Results are not based on assessments of statistical significance. Overall, fewer whales were caught on hooks with cage or chain devices (0 whales) than on hooks without devices (4 whales). Whale-damaged fish were recorded on fewer hooks with cage or chain devices (3 hooks) than on those without (24 hooks). Catch rates of the five most abundant target fish species did not differ significantly between hooks with or without the devices (see original paper for data). Seven fishing vessels deployed a total of 94 ‘long line’ fishing lines (34–42 km long) across two areas during eight trips. Each fishing line consisted of a treatment section (<1,000 branch lines with cage or chain devices attached to alternate hooks, each separated by a hook without a device) and a control section (<1,000 branch lines without devices). Devices were set to automatically trigger and cover caught fish with two steel chains or a cone-shaped nylon and aluminium cage. An observer on board each fishing vessel recorded catches and entangled whales during each of 94 hauls in 2010–2013.

(Summarised by: Anna Berthinussen)