Pollock Conservation Cooperative Research Center
2005 Awarded Research Projects
Predation on Northern Fur Seals in the Pribilof Islands: A Baseline Study Local and Traditional Knowledge Survey and Fishery Logbook Program
Kate Wynne, Bruce Robson, Desiree Lekanof,, Michael. Brewer, Andy Malavansky, Aquilina Lestenkof and Amanda Merklein
Award: $66,479
Estimated completion: November 30, 2006
Abstract
During 2006, the St. George Island Traditional Council, in collaboration with the St. Paul Island Tribal Government, Community and Ecology Resources and the University of Alaska, Fairbanks collected baseline information on the distribution and behavior of predators on northern fur seals in the Pribilof Islands region. We used two methods to collect data; a logbook program in the local halibut fishery, and a local and traditional knowledge (LTK) survey. Emphasis was placed on assessing current and historical trends in the location, numbers and seasonality of killer whale and Steller sea lion observations, as well as the frequency and extent of observed predation events. During the 2006 commercial halibut fishery, 15 boats from St. Paul and 3 boats from St. George participated in the logbook program, representing nearly complete coverage of the local fleet. From mid-June through late-September, fishermen from ten boats reported 21 sightings of killer whales in both the near-shore waters around the Islands and at the continental shelf break, however no direct predation events were observed by local fishermen. A total of 48 LTK interviews were conducted and interviewees reported 29 sightings of killer whales during 2006. Predation on northern fur seals by both killer whales and Steller sea lions was reported during LTK interviews in observations spanning the period from 1976 to the present. Gear interactions with killer whales were reported by fishermen on local vessels, however killer whale depredation on halibut longline gear was only observed in the distant waters near the continental shelf break and not in the near-shore waters around the islands. Our results are consistent with the characterization of killer whale ecotypes in the eastern North Pacific and more recently in the eastern Aleutian Islands. Killer whale observations in the near-shore waters of the Pribilof Islands were consistent with the transient ecotype; they were observed in small groups, were observed preying on marine mammals and did not interact with fishing vessels or appear to consume fish. Killer whales encountered by Pribilof fishing vessels near the continental shelf-break were consistent with resident killer whales; they occurred in larger groups, interacted with fishing vessels and ate fish from halibut longlines.
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