NATIONAL MARINE MAMMAL LABORATORY (NMML)

Workshop on Alaska Harbor Seal-Vessel Interactions

Biologists from the National Marine Mammal Laboratory's (NMML) Polar Ecosystems Program attended a workshop aimed at coordinating studies of the potential disturbance of harbor seals by vessel traffic, sponsored by the Alaska Native Harbor Seal Commission, in Yakutat, Alaska, 14-15 November 2002. Vessel disturbance studies are currently under way in the ice fields emanating from the tidewater glaciers of Disenchantment Bay (Yakutat Bay), Glacier Bay National Park, Aialik Bay (Kenai Fjords), and Tracy Arm (in Southeast Alaska). The floating ice calved from these glaciers provides stable platforms on which harbor seals rest and give birth to young. These areas are also frequented by private boats, tour boats, and cruise ships because of their unique natural beauty and wildlife.

The first day of the workshop was devoted to presentations on the status of current studies by researchers from NMML, the University of Alaska Southeast, and the Alaska SeaLife Center. The second day involved a discussion of the technical aspects of the studies (e.g., study design, data collection, and technological and analytical approaches) and how to enhance comparisons between sites by expanding or adapting methodologies.

The local Yakutat Tlingit Tribe has raised concerns that cruise ship traffic in Disenchantment Bay may be adversely affecting harbor seal populations, in turn degrading the tribe's subsistence resource. NMML biologists studied interactions between harbor seals and cruise ships in Disenchantment Bay during the pupping season (May to July) of 2002. The first report detailing the methods and accomplishments, including the first findings related to shipboard observations, is expected in January 2003.

By John Jansen, Peter Boveng, and John Bengtson.
 

CALIFORNIA CURRENT ECOSYSTEM PROGRAM

A study of the incidence and impact of hookworm infections in California sea lion pups was continued with sampling trips in October, November, and December 2002 at San Miguel Island, California. The study began in June 2002, and preliminary results indicate that hookworm infections are a significant source of pup mortality during the first 6 months of life. Preliminary estimates of the pup mortality indicate that up to 40% of the pups die in the first 6 months of life.

The pathology associated with the mortalities changed over time. Mortalities occurring in July were due mostly to starvation or anemia as a result of hookworms. Between August and December, however, mortality was more often due to systemic infections caused by intestinal bacteria released into the body cavity after hookworms punctured the intestinal wall. The study will continue in January and February 2003 to determine the age at which hookworm infections are no longer a significant source of mortality for California sea lion pups and to determine a pup mortality rate for the 2002 cohort.

By Sharon Melin.
 

CETACEAN ASSESSMENT AND ECOLOGY PROGRAM:

Ecology of Southeast Alaska Killer Whales

Research on the abundance, distribution, and stock structure of Southeast Alaska killer whales was conducted in May and September 2002. Surveys included all inland waterways of Southeast Alaska, ranging from Juneau to Ketchikan. Logistic support was provided by the NOAA ship John N. Cobb. The research efforts represent the continuation of a long-term project initiated by NMML scientists in 1989 to characterize the natural history of Southeast Alaska killer whales.

Abundance and trends of this species have been established through photo-identification methodology. Comparison of photographic matches among geographical areas has allowed researchers to determine short- and long-range movements and habitat use. Killer whale stock structure has been determined through genetic research employing biopsy sampling techniques. Three eco-types known to inhabit the study area are termed resident, transient, and offshore types. Blubber obtained during the biopsy sampling has been analyzed for contaminant levels by scientists at the Northwest Fisheries Science Center. Contaminant levels in Southeast Alaska killer whales will be compared to those in killer whale samples collected throughout the North Pacific. By following whales for extended periods of time, we also have collected valuable data on dietary preferences by different whale pods and calculated transient whales' kill rates of various species of marine mammals occupying the Southeast Alaska study area.

By Marilyn Dahlheim
 

Alaska Beluga Whale Committee Meeting

Rod Hobbs attended the 13th annual meeting of the Alaska Beluga Whale Committee (ABWC) in Anchorage, Alaska, 19-20 November. The ABWC represents native subsistence beluga whale hunters throughout Alaska and beluga whale scientists. Each year a meeting is held to review harvest data and the latest research results. Hobbs presented information on movements of tagged beluga whales in Cook Inlet and the recent abundance estimate of the Cook Inlet stock. A highlight of this year's meeting was the presentation of the NOAA Environmental Hero award to the organization. ABWC President Ross Schaeffer received the award on behalf of the organization. The award was given to the ABWC in recognition of its unique approach to user-based management and its successful mix of scientific expertise and hunters' traditional, ecological knowledge.

By Rod Hobbs.

AFSC Quarterly
Research Reports
Oct.-Dec. 2002