Fairbanks -- The state would like to expand its aerial wolf control program to protect the Interior's largest caribou herd from predators.
The Fortymile caribou herd at 43,000 animals has stopped growing after numbers nearly doubled in the past eight years, according to the Fairbanks Daily News-Miner.
"The growth of that herd has stopped and the reason is more animals are dying," said information officer Cathie Harms with the Alaska Department of Fish and Game in Fairbanks. "We're relatively confident that the increase in mortality is due to predation."
The state would like to expand the aerial wolf-control program, now approved in five areas of Alaska, to cover the Fortymile herd's entire range, Harms said.
The department submitted a proposal outlining such a program to the Alaska Board of Game earlier this month during a meeting in Fairbanks, but the Game Board tabled it and all other predator control proposals until a special meeting in May.
Fish and Game is proposing to expand the existing aerial wolf control program in Units 12 and 20E and annex parts of Units 20B, 20D and 25C into the plan. The goal is to build the herd up to between 50,000 and 100,000 with a harvest of 1,000 to 15,000 caribou a year. The harvest is currently capped at 850 animals.
The Fortymile herd has been the focus of a recovery plan for the past 10 years.
It is believed to have numbered as many as 500,000 animals during the 1920s and at least 50,000 during the 1950s and early 1960s before plummeting to a low of about 5,000 caribou by the early 1970s. The herd grew to about 23,000 over the next 20 years and remained at that level until the recovery plan was put in place.
The plan included the sterilization of 15 pairs of breeding wolves and relocating more than 100 other wolves, as well as intensified trapping efforts and hunting restrictions.
The plan worked. The herd grew to 43,000 by 2003 and has fluctuated between 41,000 and 43,000 since.
"The population in the last couple years seems to have plateaued," said state wildlife biologist Jeff Gross with the Department of Fish and Game in Tok.
The sterilized wolves did their jobs, defending their territories from intruders without reproducing, which resulted in fewer wolves over a period of several years. While the herd reaped the temporary benefits of fewer predators on its range, it was just a matter of time before other wolves replaced the wolves that were sterilized or moved, Gross said.
"They're moving in and repopulating," he said. "We're seeing pack sizes of six to eight wolves or better. We're probably approaching pre-control levels but I don't know if we're there yet."
The wolf population in the new proposed control area is estimated at 210 to 225 and Fish and Game is proposing to reduce the population to no less than 50 wolves.
"All the information available indicates that wolves are the primary predator in this herd and the primary factor limiting herd growth," Gross said.
The 30 sterilized wolves are gone, likely either killed by other wolves or trapped.
"We don't have any confirmation that there are any sterilized wolves left alive," said Gross. "Our (radio) collars have all gone off the air."