Sperm whale depredation on longline surveys and implications for the assessment of Alaska sablefish

Hanselman, Dana H.; Pyper, Brian J.; Peterson, Megan J.

doi:10.1016/j.fishres.2017.12.017

Cited by 26 publications

(21 citation statements)

References 23 publications

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“…The success of this approach depends on the fishing region, the target species and the capacity of fishers to use different gear. For example, a switch from longlines to pots was recently allowed in the sablefish fishery the Gulf of Alaska to prevent sperm whales from depredating catches (Hanselman, Pyper, & Peterson, 2018).…”

Section: Gear Modificationmentioning

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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Section: Gear Modificationmentioning

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 frequencies of killer whale–fisheries interactions reported in the present study (16–85% of the fishing days per year) are high and comparable to those reported in areas of severe depredation by the species such as the Crozet Islands (on average 43.5% of the longline sets, Tixier et al, 2016 ). The interactions in the blue-eye trevalla fisheries, therefore, are likely to result in large amounts of fish being removed from longlines with potentially significant impacts on the local fishing industry, fish stocks and the killer whale populations involved ( Peterson et al, 2014 ; Tixier et al, 2015 ; Peterson & Hanselman, 2017 ; Tixier et al, 2017 ; Hanselman, Pyper & Peterson, 2018 ). In Amsterdam/St.…”

Section: Discussionmentioning

confidence: 99%

“…However, the impacts of killer whale depredation in these fisheries have yet to be properly assessed. Consequently, priority research efforts should be directed towards estimating the amount of blue-eye trevalla removed by killer whales ( Gasco et al, 2015 ; Hanselman, Pyper & Peterson, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

“…The amount of fish or bait odontocetes removed from longlines imposes increased fishing time and displacements to achieve quotas and/or to implement strategies of avoidance ( Peterson et al, 2014 ; Thode et al, 2016 ). Secondly, the amount of depredated fish is often inaccurately assessed or unaccounted when setting catch limits, resulting in biased fish stock assessments ( Peterson et al, 2013 ; Peterson & Hanselman, 2017 ; Hanselman, Pyper & Peterson, 2018 ). Finally, depredation may negatively impact the conservation of depredating odontocete populations, primarily through death/injuries from interactions with fishing gear and lethal response from fishers ( Matkin & Saulitis, 1994 ; Gilman et al, 2007 ; Hamer, Childerhouse & Gales, 2012 ; Tixier et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

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Killer whale (Orcinus orca) interactions with blue-eye trevalla (Hyperoglyphe antarctica) longline fisheries

Tixier

Lea

Hindell

et al. 2018

PeerJ

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Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale (Orcinus orca) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla (Hyperoglyphe antarctica) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010–16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation.

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“…; Hanselman et al. ). The conservation‐related consequences of depredation are complex, and perhaps even more critical.…”

mentioning

confidence: 99%

Genetic Identification of Species Responsible for Depredation in Commercial and Recreational Fisheries

Drymon

Cooper

Powers

et al. 2019

N American J Fish Manag

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Depredation, the partial or complete removal of hooked fish (prey) by a nontarget predator species, is a cryptic interaction that negatively affects predators, prey, and fishing industries. However, these interactions are rarely observed, rendering positive identification of the predator nearly impossible. We therefore tested a genetic method for predator identification. Depredated remains from sharks and bony fish were sampled with buccal swabs. Genetic material was isolated from the swabs, which we hypothesized contained oral cells from the predator. A portion of the cytochrome‐c oxidase subunit I locus was amplified using prey‐specific blocking primers and sequenced in high depth using a metagenetics approach. We sequenced haplotypes from the remains of four sharks, where the predator was visually confirmed, and four bony fish, where the predator was unknown. For all interactions with known predators, our technique suggested the correct predator species. For all interactions where the predators were unknown, our technique suggested species previously confirmed as perpetrators in depredation events. Our findings provide a basis for the development of a genetic technique for predator identification, while highlighting challenges to be overcome before predator identification can be applied to large‐scale fisheries.

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Sperm whale depredation on longline surveys and implications for the assessment of Alaska sablefish

Cited by 26 publications

References 23 publications

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

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

Killer whale (Orcinus orca) interactions with blue-eye trevalla (Hyperoglyphe antarctica) longline fisheries

Genetic Identification of Species Responsible for Depredation in Commercial and Recreational Fisheries

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