The fact that the commercial catches of herring before 1960 were in excess of what we see in total biomass today suggests that herring was once the dominant nearshore species in the Gulf of Alaska. Historical data show that sea lion and seabird populations thrived during the periods of high herring abundance. Whereas, our methods will address the fishery competition for herring as a hypothesis, there still remains the need to conduct research into the climate-influenced physical mechanisms that could have played a role in the demise of the herring stocks. This article presents the first measurements of sea lions herding and feeding on herring at night. We are currently conducting our second year of synoptic measures sea lions and prey fish that includes a feasibility study of using nighttime airborne lidar and daytime airborne predator searches to find overwintering aggregations of herring along Alaska's rugged shorelines 60 that we can transfer our approach and technologies to other areas efficiently.
Early results suggest that our large scale search capabilities are feasible.
We will also address a host of directional hypotheses and determine the magnitude of the differences through numerical techniques. This research is a prerequisite for understanding underlying mechanisms of overwinter survival and mortality of Steller sea lions. Funds are requested to support two years of data collection and analysis to continue the collaborative research effort started in 1993 in PWS with the first herring surveys and expanded in 2000 to Steller sea lions.