2010 Surveys of Steller Sea Lions in Alaska

April 26, 2010

NMFS conducted surveys in summer 2010 to assess abundance, trends, and distribution of Steller sea lions (Eumetopias jubatus) in Alaska. An aerial photographic survey to assess adult and juvenile (non-pup) sea lions was conducted from southeast Alaska through Amchitka Pass in the Aleutian Islands from 7 June to 3 July 2010 using a NOAA Twin Otter aircraft. A second aerial survey was conducted from 10- 13 July 2010 from the southwestern tip of the Kenai Peninsula through southeast Alaska to obtain a replicate, ‘late’ non-pup count to assess movement between the threatened eastern and endangered western distinct population segments (DPSs, or stocks) during the breeding season. An additional objective during the aerial surveys was to estimate pup production at sites surveyed at least 10 days after the mean sea lion birth date (which ranges between 4-14 June in Alaska). NMFS also counted pups and non-pups (on-site counts) at five rookeries and haulouts in the western Aleutian Islands on 22-24 June and counted pups at the Walrus Island rookery (near the Pribilof Islands in the Bering Sea) on 16 July using the USFWS RV Tiĝlâx.