Using Mark Recapture Techniques to Estimate Local Abundance and Movement of Atka Mackerel, an Important Steller Sea Lion Prey in the Aleutian Islands

This study will examine local abundance and movement of Atka mackerel an important prey species of Steller sea lions in the Aleutian Islands.  Groundfish stocks in Alaska are managed at large scales, however important ecological interactions, such as predation, spawning and habitat selection occur on local scales.  This study intended to study the interactions between fisheries and Steller sea lions at these local scales.

In 2000, the National Marine Fisheries Service concluded that the Alaska groundfish fishery posed a threat to the recovery of the endangered Steller sea lion population.  Protection measures were put in place, including Trawl Exclusion Zones and fisheries closures in Critical Habitat around sea lion rookeries and haulouts.  This talk will give an overview of a multiyear study assessing the small-scale abundance, movement, and local exploitation rates of Atka mackerel, the dominant prey of sea lions in the Aleutian Islands, in relation to management boundaries such as Trawl Exclusion Zones.  We accomplished this goal through tagging, releasing and recovering Atka mackerel at several sites in the Aleutian Islands from 2002-2012.  The results of this study were included into a multi-species food web model including Steller sea lions to estimate prey consumption at these local scales.