Developing a pinniped foraging hotspot map

Investigators: Scott Pearson (WDFW) and Beth Gardner (UW)

This project uses the latest developments in hierarchical distance models to build predicted density surfaces for harbor seals and California and Steller sea lions in the U.S. portion of the Salish Sea. This work will result in a series of maps depicting pinniped in-water densities by season that will identify hotspots, cold-spots, and intermittent cold/hotspots of density. This product is a continuous density surface map (not haul-out estimates) that accounts for imperfect detection and is broad in spatial, seasonal, and temporal scope. The project team will refine existing maps to not only identify high density areas but also areas where harbor seals are likely targeting juvenile salmon by integrating harbor seal dive location and dive profile information with the broader survey data. Finally, they will evaluate the relative influence of ecological and oceanographic variables (e.g., tidal currents, distance to river mouth, distance to haul out, etc.) on pinniped abundance and distribution, and ultimately identify areas of highest predation risk for salmon.

A CA sea lion snacks on a salmon, while a gull hopes to get a piece!