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Decline of Unimak Caribou Concerns State Wildlife Managers


ANCHORAGE – Faced with the imminent and perhaps irreversible decline of caribou on Unimak Island, the Department of Fish and Game has developed a plan to restore this once valuable subsistence resource.

The plan would include selective harvest of wolves on caribou calving grounds and trans-locating bull caribou to supplement the herd. The Alaska Board of Game was recently briefed on the situation by Lem Butler, area management biologist from King Salmon. The plan will be considered for implementation by the Board at its March meeting in Fairbanks.

The Department has met with and discussed the proposed action with the U.S. Fish & Wildlife Service, which administers most of the land area of Unimak Island as part of the refuge system in Alaska. 

The latest count in the fall of 2009 found fewer than 300 caribou on the island. More worrisome, only five bulls per 100 cows were found.   Many of those bulls may be nearing the end of their life span.

“To our knowledge, bull:cow ratios below 10:100 have not been previously reported in Alaskan caribou herds,” Division of Wildlife Conservation Director Doug Larsen wrote in a Dec. 22 letter to Izembek National Wildlife Refuge Manager Nancy Hoffman who administers refuge lands on Unimak Island.

The scarcity of bulls is even more problematic due to the poor calf survival recently observed. In the most recent fall survey, a total of only seven calves were found, only two of which were males.

“Translocating bull caribou from the SAP (Southern Alaska Peninsula) caribou herd to the UCH (Unimak caribou herd) to increase pregnancy rates, coupled with a limited wolf reduction program to increase recruitment is the most effective way to quickly stabilize the declining population,” Larsen wrote.

We are encouraged by the success of our management of the SAP herd, where the removal of a relatively small number of wolves over the past two years has dramatically boosted calf recruitment from less than one calf to more than 40 calves per 100 cows, Larsen noted.

Wolves are common on the island of 1,571 square miles, and are frequently observed during caribou surveys. There is no official estimate of wolf numbers on the island but areas of similar size, habitat, and prey base on the Alaska Peninsula would indicate 20-30 wolves in 3-5 packs. Wolves would only be reduced on calving areas on the western 58% of the island

The majority of the island, 36 miles southwest of Cold Bay, is within the Alaska Maritime National Wildlife Refuge. The purposes of the refuge include conserving fish and wildlife in their natural diversity, specifically including the conservation of caribou. The purposes of the refuge also include managing it for opportunities for continued subsistence uses by local residents. 

As recently as 2002, the Unimak herd numbered more than 1,200 with 54 bulls and 31 calves per 100 cows. Calf recruitment was down to 7:100 cows by 2005 and was only 3 calves per 100 cows in 2009. The bull:cow ratio, and subsequent pregnancy rates, held up through 2007, but both have dropped precipitously in the last two years.  Biologists attribute the low pregnancy rate to the scarcity of bulls, which renders some females unable to find mates. Hunting for subsistence and other uses has been closed under both state and federal regulations since 2009 after state biologists detected a significant decline in the number of bulls.

Larsen noted that caribou on Unimak have been identified as traditional subsistence animals for local residents by the Federal Subsistence Board. About 70 people live year-round in False Pass on the eastern end of Unimak Island and many more live in nearby communities that have historically utilized the herd. 

Although USFWS has conducted several predator control programs to protect and enhance bird populations in recent years, virtually no predator management programs have been conducted to protect ungulates on national wildlife refuges in Alaska.  However, Larsen also noted that the current situation on Unimak is critical. If action is not taken soon, there is a high likelihood of losing this herd for use by local subsistence users and others for many years to come.

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