Spatial Delineation of Western Distinct Population Segment Steller Sea Lion Rookeries and Major Haulouts in Alaska
This report updates the locations of all rookeries and major haulouts used by western Distinct Population Segment (WDPS) Steller sea lions in Alaska.
NOAA Technical Memorandum NMFS-F/AKR-21
Since the early 1970s, the National Marine Fisheries Service (NMFS) has identified Steller sea lion rookery and haulout locations in Alaska from the air, ships, and on land, and obtained their locations using LOng RAnge Navigation (LORAN) coordinates and nautical charts. Over the last 20 years, coordinates collected at sites along with satellite imagery have allowed scientists to more accurately update and pinpoint rookery and haulout sites. NMFS conducts aerial surveys to count sea lions hauled out at these sites during the summer breeding season, which allow biologists to use today’s GPS technology and detailed satellite imagery to update historical site locations. This report updates the locations of all rookeries and major haulouts used by western Distinct Population Segment (WDPS) Steller sea lions in Alaska. In addition, we summarize the process used to update coordinates and delineate site extent. Older, less precise geolocation data for many of these sites have been previously identified in Federal regulations: 50 CFR § 224.103 (Special prohibitions relating to endangered Steller sea lion protection); 50 CFR § 226.202 (Critical Habitat for Steller sea lions); and the 50 CFR § 679.22 fishery restriction regulations. Since some of these regulations were developed with less accurate (than present) techniques for identifying geolocations of sites, the 2008 Recovery Plan for Steller sea lions includes a threats-based recovery criteria to correct erroneous locations for rookeries and major haulout sites designated as critical habitat and rookeries listed in the ESA special prohibitions regulation. The work documented in this memo provides such updated location data. Steller sea lion rookeries (N=51 in Alaska) as described in this report are sites where there is at least one count of 50 WDPS newborn pups, since 1973. Major haulouts (N=139) as described in this report are sites that are not rookeries, and have had significant historical counts of WDPS Steller sea lions: at least one count of 200 or more during the breeding season or at least 100 during the non-breeding season, since 1973. To classify major haulout sites for WDPS Steller sea lions in southeast Alaska, historical counts were used to calculate the proportion of Steller sea lions at these sites that were from the WDPS. See March 2008 Steller Sea Lion Recovery Plan.
Steve Lewis, NMFS, Alaska Regional Office, Sustainable Fisheries, Lowell Fritz and Kathryn Sweeney, NOAA Alaska Fisheries Science Center, Marine Mammal Laboratory