FAIRBANKS (AP) -- The latest aerial survey indicates the Western Arctic caribou herd, the state's largest, is now estimated at 430,000 animals.
That would be down by about 30,000 from the last survey done in 1996.
But biologists with the Alaska Department of Fish and Game say it's not clear if the herd has declined or if it was under-counted due to cloudy conditions during the aerial survey.
''In a way, it's a moot point. The herd is very, very large.'' said John Coady, Alaska Department of Fish and Game western regional supervisor for the Division of Wildlife Conservation. ''And it's not crashing.''
The 1999 estimate, released last week, suggests the herd declined by about 30,000 animals since the last survey in 1996. Biologists say such a decline, if indeed true, is healthy for the herd.
The caribou roam an area slightly smaller than the state of Montana -- 140,000 square miles stretching from the Arctic Ocean to the lower Yukon River to the trans-Alaska pipeline. The herd has remained stable at more than 400,000 for more than 10 years.
''The herd is probably at or near all-time historic highs,'' Coady told the Fairbanks Daily News-Miner. ''Decline is inevitable. And a gradual decline is socially and biologically preferable to a drastic decline or crash.''
The agency has surveyed the herd 11 times since 1970 with a large-format camera attached to the belly of a plane. Normally the plane flies low over the herd, but last year the caribou clustered close to the Arctic Ocean, and fog prompted biologists to fly higher on rare clear days to capture more of the herd at one pass.
The trade-off was smaller images, making caribou calves harder to separate from cows.
''Whether in fact the herd really has declined, or whether this just reflects our inability to see animals on the photographs, we don't really know,'' Coady said. Fish and Game took 500 photos during the nearly 100 hours they spent flying over the herd.
Plus the herd is so big biologists may have missed portions, Coady said. ''Because it covers such a very, very large area, there may be 5,000 or 10,000 animals in this valley or that valley that we never saw.''
The western Arctic herd crashed in the mid-1970s, dropping from 240,000 animals to 75,000. Some combination of mild winters, improved range quality and lighter predation have fostered the growth, though biologists are not sure exactly why the herd has grown.
Some 50 villages are within the herd's migration route, making the caribou a staple in the diet of most Northwest Alaska villagers. Fish and Game estimates hunters from those villages harvest about 23,000 animals from the herd each year.
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