Too many wolverines are dying in and around Chugach State Park, according to biologists with the Alaska Department of Fish and Game.
At the moment, the population remains robust, area wildlife biologist Rick Sinnott and regional furbearer biologist Howard Golden said in a news release. But they warned it cannot continue to support the killing of four wolverines per year, as happened during the most recent trapping season.
Fish and Game could recommend the state Board of Game close the short trapping season, but the agency has not taken that step yet.
Wolverines are notoriously elusive and wide-ranging animals, constantly on the move across ranges that stretch 100 square miles or more. They are rarely seen by people.
But the biologists said new counting techniques enabled them to get a better handle on the number of the animals living in the Chugach Mountains.
A mid-April aerial survey by Fish and Game estimated 18 wolverines in the mountainous survey area between the Knik River and Portage Creek. That translates to a population density of 12.7 wolverines per 1,000 square miles, similar to wolverine density in more remote parts of Alaska.
"This is the most precise wolverine estimate ever conducted in Alaska," said Earl Becker, the biostatistician who designed the technique and participated in the Chugach wolverine count.
The bad news, according to the biologists, is that an 18-animal population can't support losing four animals per year. Six wolverines were taken the previous winter.
"The average annual harvest rate during the past two winters is about 23 percent -- three times what is thought to be sustainable," the biologists noted.
Because of wolverines' slow reproductive rates, biologists believe they can be harvested on a sustained-yield basis at a rate of 7 percent to 8 percent -- or one to two wolverines per season.
As troubling as the small size of the local population is the fact trappers have taken more female than male wolverines, Golden said.
"Across the state," he said, "trappers report about 60 percent males in their harvest. But eight of 10 wolverines trapped in the Anchorage area in the past two winters have been females."
High proportions of females in the harvests indicate the population may be over-trapped, Golden said, and will make it harder to rebound.
Biologists speculate the local population has held its own only because other wolverines have migrated into the area.
And while Sinnott found that heartening, "the high harvests of the past two years probably cannot be sustained," he said.
Contact Craig Medred at 257-4588. |
