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Fisheries interaction data suggest variations in the distribution of sperm whales on the Kerguelen Plateau
conference contributionposted on 2019-01-01, 00:00 authored by Paul Tixier, Dirk Welsford, Mary-Anne Lea, Mark Hindell, Christophe Guinet, Anais Janc, Gaetan Richard, Nicolas Gasco, Guy Duhamel, Rhys Arangio, Maria Ching Villanueva, Lavinia Suberg, John ArnouldJohn Arnould
The emergence of longline fishing for Patagonian toothfish (Dissostichus eleginoides) on the Kerguelen Plateau over the past two decades is concomitant with the development of depredation-type interactions by sperm whales (Physeter macrocephalus). Through a unique collaboration between the French and the Australian fisheries operating respectively around Kerguelen, and Heard Island and McDonald Islands (HIMI), this study preliminarily investigated the spatio–temporal variations of the rate of occurrence of sperm whale depredation on the Kerguelen Plateau. Between 2011 and 2016, sperm whales depredated toothfish on 29.1% of all longline sets and over 49.4% of the fished area. The probability of vessels to experience depredation decreased with the latitude and decreased in winter. Vessels operating in Kerguelen experienced significantly higher rates of occurrence of sperm whale depredation (33.2 ± 4.5% of sets; 48.2 ± 7.2% of the area) than vessels operating in HIMI (3.1 ± 1.2% of sets; 5.4 ± 2.0% of the area) over the 2011–2016 period, but also during any season of the year. The results suggested that heterogeneity in the distribution of sperm whales is likely a key driver of depredation. The Kerguelen Plateau fisheries represent a unique opportunity to investigate the spatial factors influencing this distribution, and therefore to predict the occurrence of depredation.