Testing a passive deterrent on longlines to reduce sperm whale depredation in the Gulf of Alaska

Published source details O'Connell V., Straley J., Liddle J., Wild L., Behnken L., Falvey D. & Thode A. (2015) Testing a passive deterrent on longlines to reduce sperm whale depredation in the Gulf of Alaska. ICES Journal of Marine Science, 72, 1667-1672.
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This study is summarised as evidence for the following.

	Action	Category
	Attach acoustically reflective objects to fishing gear Action Link

Attach acoustically reflective objects to fishing gear

A controlled study in 2012 in a pelagic area in the Gulf of Alaska, USA (O'Connell et al. 2015) found that attaching acrylic beads next to fishing hooks did not reduce sperm whale Physeter macrocephalus predation on catches of target sablefish Anoplopoma fimbria. Catch rates of sablefish when sperm whales were present did not differ significantly between fishing gear with and without beads attached next to hooks (data not reported). The number of whale vocalizations associated with predation events (rapid clicks followed by a pause) also did not differ significantly between fishing gear with and without beads (data not reported). In March–August 2012, four commercial fishing vessels deployed 24 ‘long line’ fishing lines each divided into five experimental units. Each unit (comprising 4 x 183 m sections of gear with 168 hooks on each) was randomly assigned as a treatment (25 mm acrylic sphere ‘beads’ attached next to hooks) or control (no beads). An observer on board the fishing vessels recorded sablefish catches during hauls of 32 units of fishing gear in which whales were present. Acoustic recorders attached to each of the 24 fishing lines recorded sperm whale vocalizations.

(Summarised by: Anna Berthinussen)