NATIONAL MARINE MAMMAL LABORATORY (NMML)

Alaska Ecosystems Research Program

Steller Sea Lion Pup Survey Cruise

The Alaska Ecosystem Program counts Steller sea lion (Eumetopias jubatus) pups at rookeries and haulouts in the Aleutian Islands through the eastern Gulf of Alaska to monitor population trends. Specific sites visited alternate between odd and even years to reduce disturbance of the animals. At select rookeries, pups are handled to assess condition and health status, and some are marked permanently for studies estimating survival and other vital rates. Sites are also observed for the presence of previously marked sea lions.

The Alaska Ecosystems Research Program conducted a Steller sea lion pup survey cruise in the central Aleutian Islands through the eastern Gulf of Alaska from 20 June through 7 July in the 2004 field season. Specific cruise objectives were to count numbers of pups at 22 rookeries and haulouts between Adak Island (in the central Aleutian Islands) and Outer (Pye) Island (in the eastern Gulf of Alaska); handle and sample pups at 11 sites, brand pups at Marmot and Sugarloaf Islands; collect freshly-dead pups from Kasatochi Island for a UAF radionuclide persistence study; collect scats for dietary analysis; and search for previously branded and tagged sea lions. Observations of other marine mammals encountered during transits or near rookeries were recorded and entered onto platform of opportunity forms by ships crew.

Program activities in 2004 year were coordinated with aerial surveys conducted by the Southwest Fisheries Science Center; rookery and haulout observations in the Shumagin Islands by the Aleutians East Borough; field-camp based observations at Ugamak and Marmot Islands, and similar pup monitoring activities in southeast Alaska by the Alaska Department of Fish and Game (ADF&G), and in Russia under contract to North Pacific Wildlife Consultants with NMML and in collaboration with the Alaska Sea Life Center.

By Brian Fadely

California Current Program

San Miguel Island Research

Population assessment studies of California sea lions at San Miguel Island, California, began in April and will continue through October 2004. The studies focus on the description of age-specific distribution and estimation of age-specific survival and reproduction. In April, juvenile California sea lions were captured and instrumented with satellite telemetry instruments as part of a study to describe the distribution of different age and sex classes of California sea lions on San Miguel Island. The animals frequented San Miguel Island and foraged in the Southern California Bight. The study indicates that juveniles and adults feed in different foraging areas.

In early May, a 3-month field season began to continue the long-term studies on the population status of California sea lions. Daily counts of pups and adults indicate that the pup production will remain high in 2004. Resighting effort to determine survival and reproductive rates of branded California sea lions began on 20 May and will continue through August. At the end of June, observers had 3,425 sightings of branded California sea lions representing 676 individuals between ages 1 and 17.

Collections of dead California sea lion pups were conducted in early May to document the effects of domoic acid toxicity on newborn California sea lions as part of the NOAA Ocean and Human Health Initiative research program. Collections of dead pups will continue in July, August, and September to document the level and causes of California sea lion pup mortality.

In May, daily pup counts and resighting effort of tagged adults were conducted for northern fur seals at San Miguel Island, California to assess the population status and survival rates. The pup counts indicate that pup production will be high and may have finally recovered from the significant decline that occurred during the 1997-98 El Niņo event.

By Sharon Melin


Harbor Seal Surveys

The year 2004 is the first year since 1999 that Washington State harbor seals from both the coastal and inland stocks will be counted. Aerial surveys of the coastal harbor seal stock were flown during the June pupping season; surveys of the inland stock will be flown in August. Estimated counts of the coastal stock are 1,600 greater than estimate of K (carrying capacity) in Washington State for 1978-1999. The estimated coastal total of 13, 019 harbor seals is about 15% higher than expected and equal to peak numbers seen in the early 1990s. In 1999, both stocks were very close to the predicted K. Counts from photos of both stocks will be completed in the fall and will determine if the counts are as high as the estimates and if a similar increase has occurred in the inland stock.

By Harriet Huber

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AFSC Quarterly Research Reports Apr-June 2004