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Seals and volcano booming on Bogoslof Island

January 13th 8:18 pm | Jim Paulin, The Bristol Bay Times-Dutch Harbor Fisherman Print this article   Email this article  

Just like Bogoslof Island itself, the northern fur seal population on the volcanic dot of a rock has "boomed" and "skyrocketed," according to a federal marine mammal expert.

Marine mammal scientists hope to take a look this summer to see if the northern fur seal population keeps thriving on Bogolsof Island, assuming the volcanic island in the Bering Sea hasn't self-destructed, according to biologist Tom Gelatt of the National Oceanic and Atmospheric Administration's Alaska Fisheries Science Center in Seattle.

"In summer 2017 the NOAA scientists will be surveying Steller sea lions in the western and eastern Aleutians? Whether or not we visit Bogoslof will depend on the condition of the island at that time and the volcanic activity? A lot could happen in the next six months to that little rock," Gelatt said.

And even if its not code red, the highest volcanic alert level, "I don't think I'll be camping on it," he quipped.

In 2015, scientists doing a "pup count" of newborn baby seals saw continued growth of the population that occupies the island only during the summer and early fall, and spends the rest of the year at sea.

The estimated pup count was about 27,000 newborns, a 21 percent increase since the last survey five years earlier. Adding in the adults brings the island's seal population to around 70,000, and is now larger than St. George's.

What's most amazing, he said, is that northern fur seals didn't even live on Bogoslof until 1980, and since then the population, in decline elsewhere in the Bering Sea especially on St. Paul, has "skyrocketed" on the tiny island about 60 miles northwest of Unalaska

"It's a little rock with a lot of life and a lot of puffins," he said, saying the seabirds live on a grassy ridge in the middle of the island.

"It's boomed," Gelatt said, referring to the seal population, and not the island itself, though Bogoslof has been booming with volcanic eruptions, with 10 blasts lasting between 30 and 60 minutes from Dec. 16 to Jan. 3, and more seismic restlessness reported earlier this week.

Ash clouds have risen to 35,000 feet, and ash has been tracked as far away as Nebraska, according to the Alaska Volcano Observatory, which described the island as the summit of an underwater volcano rising 6,000 feet from the ocean floor to sea level, though with a land elevation of only 300 feet.

Bogoslof is a tough island to keep an eye on, according to AVO, even with electronic ears in Unalaska, Dillingham and Sand Point.

"Bogoslof is not monitored by a local, on-island geophysical network, which limits our ability to forecast activity at this volcano. AVO is using seismic and infrasound (pressure) sensors from Okmok and Makushin volcanoes on neighboring Umnak and Unalaska Islands to monitor activity, as well as more distant infrasound sensors in Dillingham and Sand Point. Due to the distance from Bogoslof, these sensors can detect signals produced by large explosive events, but they are not sensitive enough to detect lower-level signals that could help forecast imminent eruptions. Since the pressure waves move at the speed of sound, there is a delay of tens of minutes between eruption onset and detection at distant infrasound sensors. In addition, storms are common in the Aleutians during this time of year, and seismic and infrasound signals are often masked by wind-generated noise," according to AVO.

"Near-real-time satellite data are being used to detect explosive eruptions, to estimate volcanic cloud height and to track the dispersion of the resulting volcanic clouds. These data can also detect highly elevated surface temperatures from lava effusion or hot ash deposits, but none have been observed to date. Data from the World Wide Lightning Location Network provide near-real-time automated alerts of lightning strikes near Bogoslof that have been shown to be indicative of explosive activity at the volcano," according to AVO.

Jim Paulin can be reached at jpaulin@reportalaska.com

 

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