Twice a year, in a timeless ritual, northern Alaskan Eskimo whaling captains brave frigid waters, ice floes and flailing flukes to hunt the bowhead whale.

Now they are struggling with a more modern difficulty: the U.S. tax code.

The code, according to the Alaskan Eskimo Whaling Commission and its supporters in Washington, has put the captains in such a financial bind that it eventually could threaten the hunt--the mainstay of the Alaskan Eskimos' subsistence culture.

To set that right, Sen. Frank H. Murkowski (R-Alaska) has turned to a native inside-the-Beltway custom: taking care of a tiny local problem in a giant tax bill. Along with dozens of big-ticket items, such as billion-dollar breaks for multinational corporations, tax bills moving through Congress contain numerous small provisions.

In addition to items benefiting rural Alaska airports and seaplanes, Murkowski inserted a tax break for the whaling captains in the draft of the tax bill passed yesterday by the Senate Finance Committee.

At a cost of about $300,000 to the U.S. government over the next 10 years, the whaling provision is hardly a blip in the $792 billion in tax cuts in the huge measure. But Murkowski says it will help preserve Alaska's native culture.

The fix deals with a cultural dilemma. By custom, Eskimo whaling captains engage in a communal event, not a commercial activity. Those chosen for the honor of leading a hunt supply everything, from warm clothing and food for the crew to the projectiles and explosives that kill the whales.

But instead of recouping the costs by selling the whale, the captain is repaid only in meat and muktuk--blubber and skin--and, by custom, donates most of the meat to his community. The Internal Revenue Service won't allow the captain to write off the expenses against non-whaling income, or to take a charitable deduction.

The community, according to the IRS, isn't set up as a legal charity, and the value of the whale meat would be hard to calculate in any case. To rectify that, Murkowski's provision would allow a charitable deduction of up to $7,500.

"Our laws just don't relate well to that [subsistence] custom," said Charles A. Kleeschulte, Murkowski's spokesman.

When clothing and equipment were mostly handcrafted and food was taken from local stores of whale meat, out-of-pocket expenses for Eskimo whaling captains were minimal. But as civilization modernized their communities, whaling captains had to buy more equipment and lay in canned food and produce from stores. Expenses run into the thousands of dollars, said Jessica Lefevre, general counsel to the Alaska Eskimo Whaling Commission.

"Your place in the community is defined by your relationship to a whaling crew, and a successful captain has high status," she said. But costs have been rising, and few of the captains are wealthy.

The 150 registered captains range from construction workers to officials in local government, though only a small percentage of those take part in the spring and fall hunts, Lefevre said.

A similar break for the captains was dropped from a 1997 tax bill.

Environmental groups are wary of depleting the bowhead whale population but have not vigorously opposed subsistence hunts in the Arctic Ocean and Chukchi Sea. The hunts are carefully regulated by treaties and whaling conventions that limit the take to fewer than 20 whales a year.

"The whales are what buffalo were to the Plains Indians," Lefevre said. A small tax break, she suggested, is a price worth paying to avoid the mistakes of the past.

CAPTION: Two Eskimo women cut whale blubber for cooking. For Alaskan natives, whale hunting is not a commercial enterprise. (1987 PHOTO)