For 30 years, Alaska's northern fur seal population has not increased. But the ocean mammals are appearing in growing numbers in one unlikely place-a small island that forms the tip of an active undersea volcano. Bogoslof Island is distant and unpopulated. It sits in the eastern Bering Sea. Openings on the ground there release mud, steam and sulfurous gases, but northern fur seals find the island to be a good place for giving birth and raising their young.
It is unclear why the seals have chosen to live on an active volcanic island instead of other unpopulated islands in the area. "The surface is covered with these big blocks, some as big as 10 meters in length, which were exploded out of the vent,” said Chris Waythomas, a U.S. Geological Survey research scientist.
Northern fur seals get their name from their extremely thick fur; they have about 60,000 hairs per square centimeter. When Russian Emperor Alexander II needed money and decided to sell Alaska to the United States in 1867, fur was one of the future state's known valuables.
Most of the world's northern fur seals live in the eastern Bering Sea area. They live in the ocean from November to June and return to land in summer, when they breed and nurse pups. Between 1950 and 1988, the northern fur seal population dropped from 2.1 million to 1.1 million. Scientists do not know why they have not made a comeback. Northern fur seals were first seen on Bogoslof in 1980. NOAA researchers have since carried out periodic studies of the population.
Volcanic activity on Bogoslof has remained mostly stable. But Gelatt's crew chose not to camp there during their week-long visit in August. They feared an explosion could shoot up huge rocks. Instead, they made day trips from a secured boat. The crew counted the number of seals and examined whether images taken from above by an unpiloted aircraft could be used in future counts.