Trip reports: Pup and juvenile Steller sea lion captures in southeast Alaska and Prince William Sound October-November 2003

Gelatt, Tom

The ADF&G Steller sea lion program has been capturing young sea lions from long-term study areas in Southeast Alaska and Prince William Sound for studies focused on identifying causes of population decline through the study of immunology, toxicology, body composition, movements, and to collect samples for pathology and archival. Since 2000 these trips have been scheduled to sample animals at times and from places that are needed to fill sampling regimes. During February 2004 we attempted to capture sea lions in Lynn Canal and Frederick Sound, Southeast Alaska. Between 18-27 February the R/V Medeia was used to support 12 scientists capturing sea lions near Benjamin Island and Grand Point in Lynn Canal. This was a the second half of a collaborative project with Ben Wilson and Mary-Anne Lea of the University of British Columbia who were interested in investigating how juvenile sea lions pursue and catch their prey. To achieve this, we again focused our captures on large juvenile sea lions to increase the probability that they were weaned and independent from their mothers. However, unlike our trip in October where we were able to catch animals > 1 year and > 200kg, this time we were unsuccessful in capturing any sea lion > 150kg. We primarily captured smaller 8-month old pups (n = 20) and yearlings (n = 5). A variety of satellite and VHF telemetry devices and sonic tags were attached to the 5 yearlings and two pups received a vhf tag.. We used tooth eruption and body size to age the animals as: young of the year and 20-month old .Nine pups of the pups were recaptures of animals handled in October or June-July, 2004. In addition to instrumenting, all of the animals had a suite of physiological samples collected.