Southwest Fisheries Science Center (U.S.)

Aerial photographic surveys targeting California sea lions conducted during July 2011- 2015 were used to describe inter-island and intra-island distributions of California sea lions, northern elephant seals, Pacific harbor seals, and Steller sea lions within the Channel Islands. Age/sex class counts were made for California sea lions, Steller sea lions, and northern elephant seals, but not for Pacific harbor seals. Each island was subdivided into areas to document intraisland distribution of each species. California sea lions were found at all of the Channel Islands. However, San Miguel Island, San Nicolas Island, Santa Barbara Island, and San Clemente Island accounted for 99.8% to 99.9% of California sea lion pups counted, with San Miguel Island and San Nicolas Island having the most pups and non-pups of those four islands. In July 2015, when all islands were surveyed for elephant seals, 2790 elephant seals (61.3% of Channel Islands total) were at San Miguel Island, 932 (20.5% of total) at San Nicolas Island, and 816 (17.9% of total) at Santa Rosa Island. There were 1367 Pacific harbor seals counted at the Channel Islands in July 2015, and a single Steller sea lion was counted at San Nicolas Island in 2013.

https://doi.org/10.7289/v5/tm-swfsc-578

Technical Memorandum