Aerial and Ship-Based Surveys of Northern Sea Lions ('Eumetopias jubatus') in the Gulf of Alaska and Aleutian Islands during June and July 1990

摘要

In the 1989 aerial survey of adult and juvenile northern sea lions (Eumetopias jubatus) from the Kenai Peninsula to Kiska Island, Alaska 24,953 animals were found hauled out at 87 sites. This represented a decline of 63% from the 67,617 animals recorded for the same area in 1985. The speed and intensity of these declines led to an emergency listing on 5 April 1990 of the northern sea lion throughout its range as 'threatened' under the Endangered Species Act (55 Fed. Reg. 12645). The report summarizes the most recent northern sea lion survey information--results of 1990 aerial and ship-based surveys in Alaska. Counts were made of adult and juvenile northern sea lions at rookeries and haul-out sites from the Kenai Peninsula to Kiska Island in the central Aleutian Islands, and also of pups at rookeries from Chirikof Island in the central Gulf of Alaska to Kiska Island. These 1990 surveys repeat the National Marine Mammal Laboratory (NMML) 1985 and 1989 surveys (Loughlin et al. 1986; Merrick et al. 1987; Loughlin et al. 1990; Merrick et al. 1990).