Pollock Conservation Cooperative Research Center

2006 Awarded Research Projects

Local and traditional knowledge of interactions between fishermen and Steller sea lions

Gordon Kruse and Henry Huntington

Abstract

Abundances of marine mammal populations changed dramatically in the Bering Sea and Gulf of Alaska over the past century. Some of these changes are attributed to known ecological or human-caused events, but considerable uncertainty surrounds others, such as the decline of the western stock of Steller sea lions in the 1970s and 1980s. In the case of sea lions, one factor that has been identified but poorly studied is mortality from shooting by fishermen and others. Documenting information about the nature and extent of such shooting, together with its spatial and temporal characteristics, may provide valuable insights into the causes of the decline and the potential for recovery. In addition, commercial fishermen and regional residents are likely to have a great deal of knowledge about historical ecological events and conditions, including climate regime shifts, which have not been documented to date. Ecological knowledge is particularly sparse prior to routine fish stock assessment surveys in the 1970s (Bering Sea) and 1980s (Gulf of Alaska). Interviews that we conducted with selected fishermen and regional residents in the Kodiak, Cold Bay/Sand Point, and Seattle areas have added much information to our knowledge base. A preliminary reconstruction of mortality by fishery based on these interviews suggests that, apart from the Shelikof Strait trawl fishery in the 1980s, shooting practices do not appear to have changed appreciably from the 1950s to the 1970s. Thus, shooting mortality appears to be unable to account for a major portion of the unexplained mortality during 1974-1990. We are currently in the final stage of our project in which we are analyzing fishery data in combination with our newly acquired information on shooting to more fully investigate hypotheses about shooting-related mortality as a potential leading cause of the decline of the western stock of Steller sea lions. The final stage of our analysis was held up by a lengthy delay in obtaining data from the Alaska Department of Fish and Game, which experienced a loss of staff and a crash of the computer system containing the landings database. However, as of mid January 2009, we are in receipt of all requested data and we will complete our project and Final Report in the coming months. As our conclusions are pending the completion of these our analyses, we request that our work should be considered preliminary and not cited.

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