Science Spotlight

Why it's important:

After having declined dramatically between the mid-1970’s and the early 2000’s, the abundance of Steller sea lions in the Western stock has stabilized or started to increase. This is not the case for Steller sea lions in the Western and Central Aleutian Islands and in the nearby Commander Islands of Russia, where Steller sea lion numbers continue to decline. This may be due in part to low reproductive rates, which has led to controversial fishing regulations in the Aleutian Islands. Studies of Steller sea lions from the Medny Island rookery in the Commander Islands may provide valuable insights for comparison to the western Aleutians because the Commander Islands have been protected by a 30 mile no-fishing zone since the late 1950s. Dr. Vladimir Burkanov (former Visiting Scientist at the Alaska SeaLife Center, now affiliated with the National Marine Mammal Laboratory at NOAA’s Alaska Fisheries Science Center and the Kamchatka Branch of the Russian Academy of Science’s Pacific Institute of Geography) has been leading a comprehensive program on the biology of Steller sea lions in the Russian far east for over 20 years.

Since 2005 we have been working closely with Dr. Burkanov and other collaborators from Russia and the U.S., conducting observations of branded sea lions, and unlike the Aleutian Islands where no vital rates data exist, we have direct measurements of Steller sea lion survival and birth rates at this and 7 other rookeries in Russia. We are studying the factors that might affect these rates, such foraging ecology, fishing activity and environmental conditions as well as presence of potential competitors (e.g. northern fur seals) and predators (killer whales) to compare Medny Island to rookeries in the Russian Kuril Islands where populations are increasing. Our results should lead to insights about the causes of declining populations and the potential for fisheries interactions, and should be very applicable to the search for an understanding of the Steller sea lions situation in the western and central Aleutian Islands.

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