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Movements and dive behaviour of a toothfish-depredating killer and sperm whale

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posted on 2022-11-29, 05:07 authored by J R Towers, Paul Tixier, K A Ross, J Bennett, John ArnouldJohn Arnould, R L Pitman, J W Durban
Depredation of demersal longlines by killer and sperm whales is a widespread behaviour that impacts fisheries and whale populations. To better understand how depredating whales behave in response to fishing activity, we deployed satellite-linked location and dive-profile tags on a sperm and killer whale that were depredating Patagonian toothfish from commercial longlines off South Georgia. The sperm and killer whale followed one fishing vessel for >180 km and >300 km and repeatedly depredated when longlines were being retrieved over periods of 6 and 7 d, respectively. Their behaviours were also sometimes correlated with the depths and locations of deployed gear. They both dove significantly deeper and faster when depredating compared with when foraging naturally. The killer whale dove >750 m on five occasions while depredating (maximum: 1087 m), but these deep dives were always followed by long periods (3.9-4.6 h) of shallow (<100 m) diving. We hypothesize that energetically and physiologically costly dive behaviour while depredating is driven by intra- and inter-specific competition due to the limited availability of this abundant resource.

History

Journal

ICES journal of marine science

Volume

76

Season

Jan-Feb

Pagination

298 - 311

Location

Oxford, Eng.

ISSN

1054-3139

eISSN

1095-9289

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2018, International Council for the Exploration of the Sea