on Pacific Walrus
There are many on-going projects within the walrus section. Listed below
are just a few of the activities that keep us busy.
Population Census (pdf)
Pacific Walrus Population Survey
The U.S. Fish and Wildlife Service, in collaboration with the U.S. Geological Survey and Russian scientists from GiproRybFlot and ChukotTINRO, conducted a range-wide survey of the Pacific walrus population in March and April of 2006. The primary goal of the survey was to estimate the size of the Pacific walrus population across its spring range, the ice-covered continental shelf of the Bering Sea.
U.S. and Russian scientific crews coordinated aerial survey efforts on their respective sides of the international border. The study area was partitioned into survey blocks, and a systematic sample of transects within each block was sampled with an airborne thermal scanner using standard strip-transect survey methods. The amount of heat produced, or thermal signature, was recorded for each walrus group that was detected by a thermal scanner. A sample of walrus groups along a scanned transect was photographed using a high-resolution digital camera. Counts of walruses in photographed groups were used in a generalized linear model to determine the relationship between thermal signatures and the number of walruses in a group. This model will be used to estimate the number of walruses in groups that were not photographed but were detected by the thermal scanner.
Only walruses that are hauled out on ice can be detected in thermal imagery. Therefore, the population estimate derived from thermal scanning will be corrected for the proportion of walruses that was in the water and unavailable to the thermal scanner. Immediately prior to the aerial survey, a Russian icebreaker was used to access the Bering Sea pack ice, and satellite-linked transmitters were deployed on 46 walruses. The transmitters recorded locations and contained wet-dry sensors that recorded when walruses were hauled out on ice or were in the water. Transmitter data will be used to estimate the proportion of the population that was in the water and not available for detection by the thermal scanners. Data analysis and modeling are ongoing, and the final population estimate is being developed cooperatively by U.S. and Russian scientists. It will be released to the public in late 2008.
An accurate estimate of the number of animals harvested each year from the Pacific walrus population is important to the conservation and management of this species. It is necessary for managers to enumerate total annual removal to ensure that harvests are conducted at sustainable levels. Each year the USFWS and the Eskimo Walrus Commission (EWC) collaborate on two walrus harvest data and biological sample collection projects to gather information about the size and composition of the annual subsistence walrus harvest in Alaska (Visit the Marking/Tagging page for further details).
While the subsistence walrus harvest in Alaska is fairly well documented, the economic crisis in Russia led to the deterioration of harvest monitoring programs to the point where harvest estimates were no longer considered accurate or reliable. Since 1999, the U.S. Fish and Wildlife Service and the Eskimo Walrus Commission have sporadically sponsored a walrus harvest monitoring project in Chukotka. The project is designed to collect walrus harvest information from the eight primary walrus hunting villages in Chukotka utilizing a network of local Native harvest monitors. Russian collaborators in the project included: Chukotka TNIRO, the Naukan Production Cooperative, Yupik Eskimo Society of Chukotka, and the Union of Traditional Marine Mammal Hunters. Participating villages include New Chaplino, Siriniki, Enmelen,Yanrakynnot, Lorino, Uelen, and Inchoun and Enurmino. Each year American and Russian representatives exchange harvest data and discuss pertinent walrus conservation and management issues.
Walrus Satellite Telemetry Tagging
IN September 2007, Russian biologists from Chukotka TINRO in partnership with local hunters deployed satellite telemetry tags on 11 female walrus at the Cape Vankeerem coastal haulout on the northern Chukotka coast. These satellite tags documented the late September movements down the Chukotka coast as well as short foraging trips radiating out from a haulout at Cape Serdtse-Kamen.
In the late summer of 2007, our colleagues from the U.S. Geological Survey, Alaska Science Center in partnership with the North Slope Borough, Department of Wildlife Management and local hunters, deployed satellite telemetry tags on nine walrus offshore from Barrow Alaska. Data from these tags allowed researchers and managers some insight into walrus response to the record sea ice retreat event of 2007. http://alaska.usgs.gov/science/biology/walrus/chukchi_telemetry.html We plan to deploy several more transmitters during the summer of 2008.
Last updated: September 10, 2008