The effect of prey abundance and fisheries on the survival, reproduction, and social structure of killer whales (Orcinus orca) at subantarctic Marion Island
The effect of prey abundance and fisheries on the survival, reproduction, and social structure of killer whales (Orcinus orca) at subantarctic Marion Island
Most marine apex predators are keystone species that fundamentally influence their ecosystems through cascading top-down processes. Reductions in worldwide predator abundances, attributed to environmental and anthropogenic-induced changes to prey availability and negative interactions with fisheries, can have far-reaching ecosystem impacts. We tested whether the survival of killer whales (Orcinus orca) observed at Marion Island in the Southern Indian Ocean correlated with social structure and prey variables (direct measures of prey abundance, Patagonian toothfish fishery effort, and environmental proxies) using multistate models of capture-recapture data spanning 12 years (2006 to 2018). We also tested the effect of these same variables on killer whale social structure and reproduction measured over the same period. Indices of social structure had the strongest correlation with survival, with higher sociality associated with increased survival probability. Survival was also positively correlated to Patagonian toothfish fishing effort during the previous year, suggesting that fishery-linked resource availability is an important determinant of survival. No correlation between survival and environmental proxies of prey abundance was found. At-island prey availability influenced the social structure of Marion Island killer whales, but none of the variables explained variability in reproduction. Future increases in legal fishing activity may benefit this population of killer whales through the artificial provisioning of resources they provide.
de Bruyn, Nico
3257867f-eda3-4ddf-baa3-aaf692de19bb
Jordaan, Rowan
4d8c99fa-ad76-4da5-a9f3-f9dd8a634ae4
Oosthuizen, Chris
1b94648f-2c36-4d46-bc75-ca5b394a3f98
Reisinger, Ryan
4eaf9440-48e5-41fa-853f-d46457e5444e
de Bruyn, Nico
3257867f-eda3-4ddf-baa3-aaf692de19bb
Jordaan, Rowan
4d8c99fa-ad76-4da5-a9f3-f9dd8a634ae4
Oosthuizen, Chris
1b94648f-2c36-4d46-bc75-ca5b394a3f98
Reisinger, Ryan
4eaf9440-48e5-41fa-853f-d46457e5444e
(2023)
The effect of prey abundance and fisheries on the survival, reproduction, and social structure of killer whales (Orcinus orca) at subantarctic Marion Island.
Zenodo
doi:10.5061/dryad.905qfttr3
[Dataset]
Abstract
Most marine apex predators are keystone species that fundamentally influence their ecosystems through cascading top-down processes. Reductions in worldwide predator abundances, attributed to environmental and anthropogenic-induced changes to prey availability and negative interactions with fisheries, can have far-reaching ecosystem impacts. We tested whether the survival of killer whales (Orcinus orca) observed at Marion Island in the Southern Indian Ocean correlated with social structure and prey variables (direct measures of prey abundance, Patagonian toothfish fishery effort, and environmental proxies) using multistate models of capture-recapture data spanning 12 years (2006 to 2018). We also tested the effect of these same variables on killer whale social structure and reproduction measured over the same period. Indices of social structure had the strongest correlation with survival, with higher sociality associated with increased survival probability. Survival was also positively correlated to Patagonian toothfish fishing effort during the previous year, suggesting that fishery-linked resource availability is an important determinant of survival. No correlation between survival and environmental proxies of prey abundance was found. At-island prey availability influenced the social structure of Marion Island killer whales, but none of the variables explained variability in reproduction. Future increases in legal fishing activity may benefit this population of killer whales through the artificial provisioning of resources they provide.
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Published date: 19 May 2023
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Local EPrints ID: 477238
URI: http://eprints.soton.ac.uk/id/eprint/477238
PURE UUID: 9595452c-58f6-4145-92e6-b23e0e3974c4
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Date deposited: 01 Jun 2023 16:52
Last modified: 02 Jun 2023 01:56
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Contributors
Contributor:
Nico de Bruyn
Contributor:
Rowan Jordaan
Contributor:
Chris Oosthuizen
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