Killer whales depredating on survey longline.

The problem of depredation (removal of fish from fishing gear) by killer whales and sperm whales is common during the AFSC longline survey. Killer whales often depredate on sablefish in the Aleutian Islands, Bering Sea, and Western Gulf of Alaska. Sperm whale depredation is most common in the Eastern and Central Gulf of Alaska. Both species take fish off the longline during retrieval, resulting in loss of catch and gear damage. Research is being conducted during the longline survey to better understand depredation. Depredation rates by sperm whales during the survey have been estimated and photographic identification of sperm whales is done to help understand the number and movements of sperm whales in the Gulf of Alaska. Sperm whales have been tagged from the survey using satellite tags to better understand movement and diving behaviors and genetic biopsies have been collected to investigate stock structure. In addition, depredation events and the presence of whales are recorded during the survey, which will help determine if depredation is increasing over time.

Satellite tagging of sperm whales.

Contact:
Chris Lunsford
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries

Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
Chris.Lunsford@noaa.gov