U.S. and Russian Federation Complete Largest Survey of Ice-associated Seals
A team of researchers from the U.S. and Russia has completed the largest survey ever for seals that live in sea-ice habitat. The survey, conducted in April and May of 2012 and 2013, will provide the first comprehensive estimates of abundance for bearded, spotted, ribbon, and ringed seals in the Bering Sea and Sea of Okhotsk.
Scientists conducted the aerial survey using three airplanes—two operating from Alaska and one from the Russian Far East. They flew 90,000 kilometers (56,000 miles) of survey track, covering an area of ice more than twice the size of the state of Texas. Because ice-associated seals live in vast and remote pack ice regions where weather can be cold and unpredictable, aerial surveys are the safest and most cost-effective way to study them in their natural environment and enable scientists to cover large areas in a relatively short amount of time.
Figuring out how to efficiently and safely survey the region for seals has been a focus for scientists at the NOAA Alaska Fisheries Science Center and a multi-agency team of Russian collaborators for several years. Scientists now have some new tools in their toolbox.
“Emerging technology and analytical methods have finally made it feasible to enumerate these charismatic but elusive wildlife species,” said Peter Boveng, leader of the Polar Ecosystems Program at NOAA’s Alaska Fisheries Science Center that conducted the U.S. portion of the project.
Spring is the best time to survey because the seals concentrate within the ice pack and spend more time on the ice (where they can be seen and counted) while they give birth to pups, nurse, and molt their coats. Both U.S. and Russian scientists used advanced thermal imaging to detect the warm bodies of seals against the background of the cold sea ice. High-resolution digital images were also collected to help identify the species of seals detected by the thermal imagers; more than 1.8 million photos were collected by the U.S. team. New statistical approaches were also developed to tackle the unique challenges posed by the rapid shifting and melting of ice that occurs annually during the spring months.
Springtime in the Bering Sea is important not only for seals, but for many other species and the Alaska coastal communities that depend upon them. The seal survey team communicated regularly with Alaska Native villages to ensure that the surveys did not conflict with subsistence hunting activities, particularly bowhead whaling and walrus hunting around the communities on St. Lawrence Island and in the Bering Strait.
The results of this study will contribute to the scientific understanding of these unique marine mammals and will be used to identify, evaluate and resolve conservation concerns as required by the Marine Mammal Protection Act. The results will also help to assess the risk posed by loss of sea-ice habitat from ongoing and anticipated warming of the Arctic climate, a key concern addressed in status reviews that NOAA has conducted on all four species under the Endangered Species Act.
The project was funded by NOAA and the Bureau of Ocean Energy Management.
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