Northern fur seals are thriving on an Alaskan island that's the tip of an active undersea volcano.
Numbers of fur seals continue to grow on tiny Bogoslof (BOH-gohs-lawf) Island, a remote mass at the tip of an active undersea volcano in the Aleutian Islands.
The tip of the volcano forms a tiny island in the eastern Aleutians and northern fur seals in growing numbers use its beach as a rookery to give birth and raise pups.
The volcano two years ago spewed ash into the path of jetliners. Hot mud, steam and sulfurous gases continue to spit up from vents on the island.
Eruptions in 2016 and 2017 showered the landscape with rocks and killed all vegetation.
They also shrank and grew the island. Explosions destroyed acres of Bogoslof only to have fragmented material blown from lava vents create new real estate. The island remains about 0.5 square miles (1.2 square kilometers).
Despite the volcanic activity, the island has become a popular place for northern fur seals, known for their stocky bodies, small heads and thick coats. And researchers say the animals are giving birth in growing numbers.
Federal researchers visited the island in August to assess breeding fur seals.
Tom Gelatt of the National Oceanic and Atmospheric Administration says biologists in 2015 estimated 28,000 pups on the island. He says the 2019 estimate likely will be more than 36,000 pups.
Geographically speaking, the island is not a particularly unusual place for the seals known for their thick coats to hang out.
Most of the world's roughly 1.1 million northern fur seals breed in the eastern Bering Sea. The animals live in the ocean from November to June and head for land in summer to breed and nurse pups.
But why the seals chose volatile Bogoslof over the dozens of other uninhabited Aleutian Islands is unclear.
Fur seals were first spotted on Bogoslof in 1980, and NOAA researchers have since conducted periodic checks on the population.
By 1988, four years after the commercial harvest ended on St. Paul Island, the northern fur seal population had declined by more than half from its 1950s estimated population of 2.1 million animals
The eastern Bering Sea population of northern fur seals numbers about 635,000, with their main breeding ground on St. Paul Island, 240 miles (390 kilometers) northwest of Bogoslof.
A California stock in the San Miguel, Channel and Farallon Islands is estimated at 14,050 animals. Other northern fur seals live in Russian waters, though it's unclear how many.