Featured Image Credit:NOAA
By Alice Morris
Scientists have been studying northern fur seals on Alaska’s St. Paul Island for many decades. But a recent decline in fur seal pups has many experts worrying about the species’ future.
According to a recent study, northern fur seal pup numbers are at their lowest since 1915.
Seattle’s Marine Mammal Laboratory visits the Pribilof Islands, a group of volcanic islands in the Bering Sea, every other year to estimate the seal pup population size.
Rod Towell, a scientist who has been involved in these counts since 1992 says the decline in numbers has been noticeable.
“I’m not going to say it was full coverage, but it looked like a moving carpet in a sense,” Towell said of his early visits to the islands. “There was a movement all across the rocks. You can see them, but there’s seals moving everywhere. Whereas now it looks more patchy.”
Towell estimates that pup numbers are about half of what they were 25 years ago.
Why the sudden decline in populations?
Scientists aren’t entirely sure, but they’re taking action to find out.
“There hasn’t been commercial pressure on St. Paul Island since 1984,” says Towell of the puzzling decline. “The fur market has gone way down. We haven’t seen any real obvious mortality pressure on this population since then.”
Scientists hope that another existing research project may provide some answers.
Starting in the late 2000s, researchers began tagging individual fur seal pups on St. Paul and St. George Islands. By studying those individuals, Towell hopes to uncover what portion of the population is under the most pressure and how pup mortality rates change from year to year.
Another study that began in 2016 uses a device called the “Saildrone” to survey prey populations in the Bering Sea. Scientists hope that a better understanding of the fur seals’ available food supply may help explain current population trends.
Fur seals aren’t the only animals suffering on St. Paul Island either.
Puffin populations have been declining in recent years and, in the final months of 2016 a staggering 300 puffins washed up dead on the island, most likely the result of a food shortage.
Many experts call for more comprehensive studies of fur seals moving forwards.
The Scientific and Statistical Committee, which advises the North Pacific Management Council, believes more collaboration between the NPMC and the Marine Mammal Laboratory could help manage and protect the island’s marine mammals.
“There is a report that the fur seals are declining steadily, particularly on St. Paul Island,” the SSC notes. “But there is little information on progress that may have been made in determining when and where in their life cycle threats to fur seal survival and successful reproduction are occurring.”
Learn more about northern fur seals and current conservation efforts at http://www.fisheries.noaa.gov/pr/species/mammals/seals/northern-fur-seal.html – conservation.