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
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
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
By Rod Hobbs.
quarterly Oct-Dec 2002 sidebar
Auke Bay Lab