Killer whales and marine mammal trends in the North Pacific : a re-examination of evidence for sequential megafauna collapse and the prey-switching hypothesis


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dc.contributor.author Wade, Paul R.
dc.contributor.author Burkanov, Vladimir N.
dc.contributor.author Dahlheim, Marilyn E.
dc.contributor.author Friday, Nancy A.
dc.contributor.author Fritz, Lowell W.
dc.contributor.author Loughlin, Thomas R.
dc.contributor.author Mizroch, Sally A.
dc.contributor.author Muto, Marcia M.
dc.contributor.author Rice, Dale W.
dc.contributor.author Barrett-Lennard, Lance G.
dc.contributor.author Black, Nancy A.
dc.contributor.author Burdin, Alexander M.
dc.contributor.author Calambokidis, John
dc.contributor.author Cerchio, Sal
dc.contributor.author Ford, John K. B.
dc.contributor.author Jacobsen, Jeff K.
dc.contributor.author Matkin, Craig O.
dc.contributor.author Matkin, Dena R.
dc.contributor.author Mehta, Amee V.
dc.contributor.author Small, Robert J.
dc.contributor.author Straley, Janice M.
dc.contributor.author McCluskey, Shannon M.
dc.contributor.author VanBlaricom, Glenn R.
dc.date.accessioned 2007-12-19T16:22:07Z
dc.date.available 2007-12-19T16:22:07Z
dc.date.issued 2007-10-26
dc.identifier.citation Marine Mammal Science 23 (2007): 766–802 en
dc.identifier.uri http://hdl.handle.net/1912/1936
dc.description This paper is not subject to U.S. copyright. The definitive version was published in Marine Mammal Science 23 (2007): 766–802, doi:10.1111/j.1748-7692.2006.00093.x. en
dc.description.abstract Springer et al. (2003) contend that sequential declines occurred in North Pacific populations of harbor and fur seals, Steller sea lions, and sea otters. They hypothesize that these were due to increased predation by killer whales, when industrial whaling's removal of large whales as a supposed primary food source precipitated a prey switch. Using a regional approach, we reexamined whale catch data, killer whale predation observations, and the current biomass and trends of potential prey, and found little support for the prey-switching hypothesis. Large whale biomass in the Bering Sea did not decline as much as suggested by Springer et al., and much of the reduction occurred 50–100 yr ago, well before the declines of pinnipeds and sea otters began; thus, the need to switch prey starting in the 1970s is doubtful. With the sole exception that the sea otter decline followed the decline of pinnipeds, the reported declines were not in fact sequential. Given this, it is unlikely that a sequential megafaunal collapse from whales to sea otters occurred. The spatial and temporal patterns of pinniped and sea otter population trends are more complex than Springer et al. suggest, and are often inconsistent with their hypothesis. Populations remained stable or increased in many areas, despite extensive historical whaling and high killer whale abundance. Furthermore, observed killer whale predation has largely involved pinnipeds and small cetaceans; there is little evidence that large whales were ever a major prey item in high latitudes. Small cetaceans (ignored by Springer et al.) were likely abundant throughout the period. Overall, we suggest that the Springer et al. hypothesis represents a misleading and simplistic view of events and trophic relationships within this complex marine ecosystem. en
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Blackwell en
dc.relation.uri http://dx.doi.org/10.1111/j.1748-7692.2006.00093.x
dc.subject North Pacific en
dc.subject Killer whale en
dc.subject Steller sea lion en
dc.subject Sea otter en
dc.subject Harbor seal en
dc.subject Fur seal en
dc.subject Ecosystem en
dc.subject Predation en
dc.subject Whaling en
dc.subject Population dynamics en
dc.title Killer whales and marine mammal trends in the North Pacific : a re-examination of evidence for sequential megafauna collapse and the prey-switching hypothesis en
dc.type Article en
dc.identifier.doi 10.1111/j.1748-7692.2006.00093.x

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