Monster Seminar JAM - The Fishery Interaction Team: Investigating the Potential for Commercial Fishing to Compete with Endangered Steller Sea Lions for Shared Prey
Dr. Libby Logerwell, Resource Ecology & Fisheries Management, NOAA/NMFS
The Fishery Interaction Team (FIT) at the Alaska Fisheries Science Center (National Marine Fisheries Service, USA) was formed in 2000 to investigate the potential impact of commercial fishing on the spatial distribution and abundance of marine fishes. FIT researchers are presently interested in interactions between commercial fisheries and endangered Steller sea lions. Specifically, we are conducting experiments to determine whether commercial fishing operations potentially impact the foraging success of sea lions either through disturbance of prey schools or through direct competition for a common prey. The objectives of our current research projects are to: 1) test the hypothesis that commercial fishing results in depletion or disruption of prey fields at the spatial scale of tens of nautical miles and the temporal scale of weeks, and 2) evaluate the efficacy of management measures designed to mitigate competition between commercial fishing and sea lions. This presentation will provide a brief overview of our three field investigations and summarize results to date. Particular attention will be paid to the results of our research on the efficacy of trawl exclusion zones in the Aleutian Islands. Trawl exclusion zones were put into place around several sea lion rookeries in response to concerns about localized depletion of Atka mackerel, the primary prey of sea lions in the Aleutians. In order for the zones to be effective at maintaining sufficient prey for Steller sea lions there should be little movement of fish from inside to outside the zones and the abundance of fish within the zones should be high. Results to date suggest that in some areas there is little fish movement from inside to outside the exclusion zones and fish abundance inside is high. In other areas, the opposite appears to be true fish movement is high and abundance inside exclusion zones is low. These differences may be due to differences in the size and location of trawl exclusion zones between areas. The implications of these results for the design of protective measures such as trawl exclusion zones and marine protected areas will be discussed.
Date and Time:
January 29, 2004,
11:00 am - 12:30 pm