|An aerial survey photograph of an adult male ribbon seal in the Bering Sea.|
A U.S.-Russia team of researchers has designed a large-scale, springtime aerial survey using advanced imaging systems and modern statistical techniques to provide the first comprehensive estimates of abundance for ice-associated seals. The survey, scheduled to begin mid-April 2012 (depending on weather conditions), will include nearly 19,000 nautical miles of track lines over U.S. waters and 11,000 nautical miles over Russian waters. This effort, supported by NOAA, the Bureau of Ocean Energy Management (BOEM), and several Russian institutions, constitutes the largest survey effort undertaken to estimate the abundance of these important seal species. The survey will last into May, and a second survey is planned during the same time in 2013.
Our knowledge about ice-associated seals is sparse. Studying seals in the Bering Sea and Arctic waters poses many challenges that limit the ability for scientists to learn about these special animals. Four species of ice-associated seals are found in the Bering Sea: ribbon seals, spotted seals, bearded seals and ringed seals. The Bering Sea’s remote location, along with the cold and unpredictable weather, limits scientists’ ability to study these animals in their natural habitat. 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.
Aerial surveys are the best way to study ice-associated seals in their natural environment while covering large areas in a relatively short amount of time. Spring is the best time to survey because the seals concentrate within the Bering Sea pack ice and spend more time on the ice, where they can be seen and counted, while they have pups, breed and molt. 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 that may occur due to 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.
To reduce the disturbance to seals, the surveys will be conducted from altitudes of 800-1,000 feet. In the U.S. surveys, two types of aircraft will be used: a NOAA-owned and operated Dehavilland Twin Otter aircraft and a chartered long-range Aero-Commander 690. Typical survey flights will last between five and seven hours and originate from Nome, Bethel, Dillingham, and St. Paul.
Because the aircraft will be flying at altitudes too high for the human eye to identify species, high-resolution (2 cm/pixel) digital cameras will capture images to be analyzed back in the lab for species identification. Thermal sensors will be used in tandem with the digital cameras to pinpoint the seals, thus reducing the number of images that will need analyzing.
“The most novel thing about the survey is the pairing of the two imaging devices. The thermal or infrared cameras are good at detecting the warm seals on ice, but not for identifying the species of the seals. The high-resolution digital camera, provides photos that can be used for species identification, and counting seals. By putting the two together, an efficient system is created where the thermal camera finds the seals and the photo camera allows us to ID the seals.” explained, Peter Boveng, one of the principal investigators of the survey.
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 will be communicating regularly with Alaska Native villages to ensure that the surveys do not conflict with subsistence hunting activities, particularly bowhead whaling around the communities on St. Lawrence Island and in Bering Strait.
Updates from the surveys will be available on this website after survey completion.
Principal investigators: Peter Boveng, Michael Cameron, and Erin Moreland.
For more information on the Polar Ecosystems Program's research activities visit the our polar page at http://www.afsc.noaa.gov/nmml/polar/