Physical and psychological deterrence strategies to mitigate odontocete by-catch and depredation in pelagic longline fisheries: progress report

Hamer, D.J., Childerhouse, S.J.
Journal/Publisher Name
Progress report to Pacific Islands Forum Fisheries Agency, World Wildlife Fund South Pacific, and Pacific Islands Tuna Industry Association

Two devices were designed to prevent odontocetes from depredating caught fish and putting themselves at-risk of becoming bycatch. One device used physical deterrence by shouding the fish with a barrier and the other used psychological deterrence by utilizing prior negative experiences of temporary entanglement in fishing gear. Both devices fit on a branchline at a distance from the hook and descend towards a caught fish using a line tension trigger mechanism. All interactions occurred on control branchlines that were not fitted with a deterrent device, suggesting the potential of this technology to deter depredating odontocetes. The impact on fish catch rates, size, and survival was negligible.