lenn Fredericks, 46, an Athapascan Indian, has worked as a swimming-pool equipment installer, a carpenter and boss of his own small construction firm. But today, as one of a few native Alaskans in control of a slice of land bigger than all of New England, he is president of a corporation worth $8 million.

Fredericks and more than 80,000 other Alaskan Eskimos, Indians and Aleuts this year received the last installment of 44 million acres and nearly $1 billion granted them by the Alaska Native Claims Settlement Act Congress passed in 1971. Not only has the enormous stipend turned Fredericks into a big businessman, but it also has brought unaccustomed tensions to the sleepy native villages he represents.

Oil wells on the Artic north slope, seafood canning companies on the southern panhandle and timber operations in the rich forests of the interior are among the dozens of enterprises snapped up by Alaska's natives, who as a consequence are now often called just "shareholders." Real estate agents looking at good property in Anchorage or travelers checking into the state's best hotels find themselves dealing with native-run enterprises.

Yet the money and land have put enormous pressures on Frederick's Kuskokwim Corp. and the other native companies that officially hold the new assets. To keep the money and land from crumbling away in the normal wear and tear of taxes, expenses and corporate takeover attempts, they must invest the money and start developing the land.

Only 900 shareholders live in the little southwestern Alaska villages that make up Frederick's corporation, Georgetown, Napaimute, Sleetmute, Crooked Creek, Chauthbaluk, Aniak, Lower Kalskag, Upper Kalskag, Red Devil and Stony River, and they find the new demands hard to accept.

"They are so used to living off the land, taking just enough to get by," Fredericks said, sipping coffee in his small, barren office in downtown Anchorage, "and it is very hard for the old people to understand that we must develop in order to make a profit."

Many of the 13 major corporations, as well as the smaller village corporations and amalgams like Frederick's Kuskokwim that are a part of them, have already stumbled in the race to ensure profits.

"We lost a lot of money in the beginning with some businesses," Fredericks said, recalling a mapping and photography firm that had to be sold at a loss. Bad investments by some villages near Bethel have wiped out nearly all their funds, he said.

Under the terms of the Native Claims Settlement Act each native in the state received 100 shares of stock that cannot be sold until 1991. About 80,000 natives are covered by the act, including about 20,000 who live outside Alaska.

Although Kuskokwim paid its shareholders a $100 per share dividend last year, and will double that this year, most corporations have refrained from paying dividends to guarantee their financial health by the crucial 1991 date. Many natives who live in poor circumstances grumble about the lack of immediate income from their shares.

"The great danger is that in 1991 some third parties could come in and buy them off, control the vast amount of land that they own," Fredericks said. "Once you sell that share, you are a non-native. We cannot do anything for you."

To keep their shareholders on their side, the corporations are maneuvering to provide jobs and other opportunities. Byron Mallott, 39, a Tlingit Indian who is board chairman of Sealaska Corp., justified his heavy investment in the high-risk, low-return fishing business to Alaska Industry magazine: "To do a classic financial investment analysis, some folks must scratch their heads and say 'Those guys are crazy!' "

But he noted that panhandle Indians traditionally have earned their living fishing, and "When you factor in the positive effect you have on shareholder employment, you can . . . justify that kind of investment decision."

Mallott's Sealaska, the largest of the native corporations, with $144 million in revenues last year, made it into Fortune magazine's top 1,000 corporations, the first Alaska-based company to make the list.

Mallott and his board hired a non-native, former International Telephone & Telegraph Corp. executive Mike Chittick, 38, as president, a decision that brought criticism from some shareholders. The criticism has been muted by the company's initial success.

Chittick, in an interview, acknowledged that the need to improve employment and services for shareholders makes the native corporations unique, but said, "We still have to be competitive in the marketplace, just like any corporation."

Still, the social concerns and small-town backgrounds of the native corporation executives may be helping the morale of even non-native employes.

At the Nana Camp hotel, a thriving hostelry for oil workers run by the Eskimo Nana Corp. on the North Slope, hotel staffers Don Kirkpatrick and Edna Foxglove, both 28, sipped beers and talked about why they liked working for Nana.

"I feel like it's family," said Kirkpatrick, a non-native from New Mexico. "That's the way I feel," said Foxglove, an Eskimo from Selawik, far to the west.

Some seemingly unprofitable native occupations also may turn into good businesses.

The Nana Corp. invested in reindeer herds because that was a traditional pursuit of its shareholders, though it didn't hope to see much return on its investment. But, suddenly Orientals, who have long believed in powdered rhinoceros horn as an aphrodisiac, turned to reindeer antlers as a substitute. The Nana reindeer herds now bring in more than $300,000 a year.