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BookmarkScienceDaily (May 24, 2001) — GALVESTON - It's an act that would rival the best work of Siegfried and Roy: How are 2,000-pound Steller sea lions disappearing so quickly?
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The Steller sea lion, the largest of all sea lions, has suffered declining numbers that threaten its existence. In some parts of the world, its numbers are now only 15 percent of what they were in 1970, which is why it has been placed on the endangered species list.
Texas A&M University at Galveston researchers Markus Horning and Jo-Ann Mellish are on a quest to find out why the animal's future is in doubt, and with the help of an $800,000 National Science Foundation grant and a $1 million National Marine Fisheries Service grant, they may be able to unravel at least some of the riddle.
Horning will use satellite-linked, close-range imaging to monitor the lumbering creatures, whose numbers are quickly dwindling, especially around the Gulf of Alaska and near the Aleutian Islands, ground zero for many Stellers.
Horning will place several digital cameras with transmitters near Steller breeding grounds. He hopes to get an accurate census count of just how many Stellers are out there, and with help of the images, calculate the body size of those photographed.
"The body size will tell us the approximate age of the animal, which in turn can tell us several things," Horning explains. "The body size can tell us if the Steller is getting an adequate food supply. If no young Stellers appear to be growing much larger, that might indicate some sort of nutritional stress, such as not enough food supply to begin with. "Also, the percent of fat stored in the animal can tell us about its eating habits and its food supply."
A possible cause of less-than-ideal food supply: overfishing in the area.
Researchers have for years believed that commercial fishermen in the area have netted huge supplies of pollock and mackerel, the Stellers' primary food source. Fewer fish ultimately could lead to fewer Stellers, a cycle that may have gotten out of sync for the last 30 years.
"If there is nutritional stress, is it because of overfishing? That's one big question we hope to answer," Horning adds. There are two kinds of Stellers - the Eastern stock and the Western stock, so named because they inhabit those areas of the Gulf of Alaska. The Eastern stock population has remained stable, Horning says.
But the Western stock has diminished greatly - from 170,000 in 1970 to only about 25,000 today. Its decline parallels those of other endangered animals in the area, such as the sea otter, harbor seal and Orca whale.
"The Gulf of Alaska and Behring Sea are two of the most important ecosystems in the world," Horning adds. "We hope to find some answers. The decline in Steller sea lions and other species could be potentially devastating to the area."
