Assessing the impact of toothed whale depredation on socio-ecosystems and fishery management in wide-ranging subantarctic fisheries

Tixier, Paul; Burch, P; Massiot‐Granier, Félix; Ziegler, Philippe E.; Welsford, Dirk; Lea, Mary‐Anne; Hindell, Mark A.; Guinet, Christophe; Wotherspoon, Simon; Gasco, Nicolas; Péron, Clara; Duhamel, Guy; Arangio, Rhys; Tascheri, R; Somhlaba, Sobahle; Arnould, John P. Y.

doi:10.1007/s11160-020-09597-w

Cited by 32 publications

(33 citation statements)

References 55 publications

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“…Interaction may also lead to a predator dependency on the fishery (Tew Kai et al 2013). In some fisheries, depredation by marine mammals results in reduced revenues (Hansel man et al 2018, Tixier et al 2020). Killer whales that were feeding near fishing vessels mostly targeted the fish outside the net (A. Rikardsen & E. Mul pers.…”

Section: Discussionmentioning

confidence: 99%

Killer whales are attracted to herring fishing vessels

Mul

Blanchet

McClintock

et al. 2020

Mar. Ecol. Prog. Ser.

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Marine mammals and fisheries often target the same resources, which can lead to operational interactions. Potential consequences of operational interaction include entanglements and damaged or reduced catches but also enhanced foraging opportunities, which can attract marine mammals to fishing vessels. Responsible fisheries management therefore requires detailed knowledge of the impact of these interactions. In northern Norway, killer whales Orcinus orca are frequently observed in association with large herring aggregations during the winter. We use a combination of biotelemetry and fisheries data to study if, to what extent and at what distances killer whales are attracted to fishing activity. Twenty-five satellite transmitters were deployed on killer whales at herring overwintering and spawning grounds, often near fishing vessels. Over 50% of the killer whale core areas of high usage overlapped with the fisheries core areas, and individual whales spent up to 34% of their time close to active fishing. We used a 3-state hidden Markov model to assess whether killer whale movements were biased towards fishing activities. Of the overall whale movements, 15% (CI = 11-21%) were biased towards fishing activities, with marked heterogeneity among individuals (0-57%). During periods of active fishing, whale movements were biased towards fishing events 44% (CI = 24-66%) of the time, with individual percentages ranging from 0 to 79%. Whales were more likely to be attracted when they were within 20 km. This information can be used in fishery management to consider potential consequences for fishers and whales.

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Section: Discussionmentioning

confidence: 99%

Killer whales are attracted to herring fishing vessels

Mul

Blanchet

McClintock

et al. 2020

Mar. Ecol. Prog. Ser.

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“…For example, intentional shooting of common bottlenose dolphins in the Mediterranean Sea and southern sea lions off Brazil and Chile was reported between 2015 and 2019 (Machado et al, 2016; Pardalou & Tsikliras, 2018; Pont et al, 2016; Sepúlveda et al, 2018). Similar practices were heavily detrimental for killer whale populations in Alaska and the Southern Ocean (Busson et al, 2019; Matkin, 1988; Poncelet, Barbraud, & Guinet, 2010; Tixier et al, 2017). In the Amazon Basin, retaliatory killing, paired with by‐catch, was described as the main driver of rapid declines of Amazon river dolphins and Tucuxis populations (Alves, Zappes, & Andriolo, 2012; Loch, Marmontel, & Simoes‐Lopes, 2009).…”

Section: Ecological Effectsmentioning

confidence: 99%

When large marine predators feed on fisheries catches: Global patterns of the depredation conflict and directions for coexistence

et al. 2020

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The sustainable mitigation of human-wildlife conflicts has become a major societal and environmental challenge globally. Among these conflicts, large marine predators feeding on fisheries catches, a behaviour termed "depredation," has emerged concomitantly with the expansion of the world's fisheries. Depredation poses threats to both the socioeconomic viability of fisheries and species conservation, stressing the need for mitigation. This review synthesizes the extent and socio-ecological impacts of depredation by sharks and marine mammals across the world, and the

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“…During this same period, Marion Island experienced decreases in penguin population sizes but increases in fur seal and southern elephant seal population sizes (Crawford et al 2003, Hofmeyr et al 2006, Bester et al 2011. Furthermore, although seasonal and not year-round, the current legal fishery at Îles Crozet is estimated to be bigger (11 845 versus 4373 longline sets between 2006 and 2018) with more depredation taking place (21% (179 tonnes) versus 6% (15 tonnes) of total catch per year) when compared to the fishery surrounding Marion Island where stocks were substantially impacted by illegal fishing prior to 2006 (Boonzaier et al 2012, Tixier et al 2020. Depredating, and non-depredating, killer whales at Îles Crozet are therefore exposed to different natural and artificial resources, which, in addition to a disrupted social structure, could account for differences in their fecundity and survival rates.…”

Section: Modelmentioning

confidence: 99%