This mist-shrouded island 13 miles off southwest Alaska is a haven every summer for thousands of bull walruses, but the noise of civilization may be driving them away.

The puffing, snorting, hissing mammals heave their 2 tons of bulk from the Bering Sea and poke their way with their huge tusks into the crowd, each seeking a spot to rest between seven- to 10-day feeding expeditions. Their favored places for hauling themselves out of the water are called haulouts.The Pacific walruses here and in lesser numbers at the six other islands of the Walrus Islands State Game Sanctuary are partly protected by the weather and the location, which make this a difficult and expensive place to visit.

The nearest town is 33 miles by charter boat. Summer weather is characterized by wind, rain and high waves that make approach by floatplane or small boat hazardous.

But with increased commercial bottomfishing and the prospect of oil exploration and development in salmon-rich Bristol Bay, all that isolation and privacy may fade, and that has some professional walrus watchers concerned.

"Walrus are pretty sensitive to disturbance," said Lloyd Lowry, a marine mammal specialist with the Alaska Department of Fish and Game in Fairbanks.

"There's more than a little concern that the noise caused by the fishery has influenced the haulout. People on the island say they sometimes can hear the radios on the bridges of the boats."

The game technicians on Round Island this summer, Polly Hessing and Judy Brandt, said they counted as many as 180 boats in the area during a peak fishing period in May.

Although the vessels were outside the two-mile limit around the sanctuary, they made enough noise to force the women to close the windows in their cabin so they could sleep.

The walrus population on Round Island varies considerably from year to year.

"In the mid-1970s, we had as many as 15,000 animals there," said Ken Taylor, a state biologist in Dillingham. "In the last two years, the herd has gone down. It was 4,400 last year and about 4,500 now. The difficult thing is there are so many reasons for the numbers to go up and down."

Changes in the weather, variations in the food chain and increased noise are believed to affect the number of walruses summering on Round Island.

"Two years does not a trend make, but we are becoming concerned," Lowry said. "Walrus are fairly traditional about where they haul out. So are sea lions. They (walrus) came back from virtually no animals in the '40s, to peak counts in the late '70s.

"But there are several other places they could go and we don't know if the herd is simply splitting up or what it's doing."

While the males are piled up on beaches as far south as Kodiak Island and Yakutat Bay, the females and their young remain with the pack ice north of the Bering Strait and into the Arctic Ocean.

"We've got a lot of haulouts on the Alaska coast that are empty now and I think because of boat traffic," said Taylor.

Thirty permits a day are available for people wishing to visit Round Island. Access is restricted to a narrow corridor fronting a grassy campground.

Although walruses get top billing, the treeless island also supports 450,000 seabirds, primarily common murres, black-legged kittiwakes, cormorants, parakeet auklets, horned and tufted puffins and gulls. Red fox are unafraid of people and often share trails with campers.

The Pacific walrus herd is believed to comprise some 234,000 animals, a return to its 18th century levels after commercial hunting severely depleted its numbers.