Assessing interactions between dolphins and small pelagic fish on branchline to design a depredation mitigation device in pelagic longline fisheries

Published source details Rabearisoa N., Bach P. & Marsac F. (2015) Assessing interactions between dolphins and small pelagic fish on branchline to design a depredation mitigation device in pelagic longline fisheries. ICES Journal of Marine Science, 72, 1682-1690.
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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 2011 in coastal waters in the Indian Ocean, off Reunion Island, near Madagascar (Rabearisoa et al. 2015) found that attaching catch protection devices made from streamers to fishing lines reduced Indo-Pacific bottlenose dolphin Tursiops aduncus and spinner dolphin Stenella longirostris predation on fish bait, but only during the first two hauls. Fishing lines with streamers attached had a lower proportion of fish partly or fully removed by bottlenose dolphins (15–26%) or spinner dolphins (3–15%) than lines without streamers (bottlenose dolphins: 50–68%; spinner dolphins: 24–65%) during the first two hauls. The proportion of partly or fully removed fish on lines with and without streamers did not differ significantly for four subsequent hauls with bottlenose dolphins present (with: 8–40%; without: 10–24%) and one subsequent haul with spinner dolphins present (with: 3%; without: 18%). Twenty ‘long line’ fishing lines (500 m long) baited with small fish were deployed in coastal waters. Each had 40 branch lines with streamers attached and 40 without. Streamers were 8 x 1 m lengths of tarpaulin (four of which were weighted) attached to the branch line above the fish. Fish status (intact, partly, or fully removed) on each branch line was recorded during six hauls with bottlenose dolphins present and three hauls with spinner dolphins present in March–June 2011.

(Summarised by: Anna Berthinussen)