For the hardly fishermen fo this rusty old whaling port, the salt breeze tastes of hope. A long siege is ending.

On Tuesday, the United States takes control of fishing rights in 2.2 million square miles of ocean, thus halting the 15 year foreign domination fo American coastal fisheries.

No longer will massive Soviet and Japanese fleets be permitted to sweep through offshore fishing grounds here like giant vacuum cleaners. The highly mechanized foreign vessels, which have decimated whole species of fish in the last decade, henceforth will yield to the smaller independent trawlers of American seamen.

Since the law was passed last year to extend U.S. jurisdiction 200 miles out to sea, fishermen from Massachusetts to Alaska have predicted are juvenation of their ailing industry.

"The Gold Rush mentality has hit." said Dan Arnold, a craggy-faced, bearded fisherman who heads the Massachusetts Inshore Draggermen's Association. "New boats are being built. New money and new people are going into fishing."

More important, the 200 miles limit represents a major effort to conserve a dwindling food supply - that one-tenth of the world's fish which live off U.S. shores.

Twenty years ago, America's rich coastal fishing grounds were thought to be inexhaustible. But in the early 1960s, foreign fishing fleets began to systematically harvest them with sophisticated trawlers, electronic equipment and huge factory ships to process the catch.

Small outdated American boats could not compete with the subsidized foreign vessels. By the early 1970s, Russian, Japanese, Polish, East German, South Korean and other foreign fishermen were hauling in 79 per cent of the fish within 200 miles of U.S. shores.

Today, according to the National Marine Fisheries Service, a federal agency, "overfishing off U.S. coasts has seriously depleted approximately 20 species and threatened others." In the Atlantic, haddock, herring, cod, halibut and mackerel catches have declind to less than 10 per cent of former yields.

"Five years ago, I'd catch 700,000 pounds of fish a year," said Arnold, who skippers a 57-foot trawler off Marshfield, Mass. "Today I'm not doing more than half that.

"Twenty years ago, there was an abundance of fish. But the foreign fleets came in and slaughtered several year classes [generations]. The fishing has never been the same."

The 200-mile-limit law, which replaces a series of loose internaional treaties, brings offshore fishing under U.S. government protection for the first time. Eight regional councils, composed of state, federal and fishing industry repersentatives, are drawing up management plans for 75 species of fish.

Under the law, American have the first shot. if the councils find a surplus of certain species, foreign vessels may apply for permits to harvest what American fishermen don't want.

Today there is only a limited market among America's fussy fishermen for such species as mackerel, pollock, hake and squid, which are heavilly fished by foreigners.

To enforce the new law the Coast Guard is acquiring several new ships and planes. If foreign vessels are caught exceeding their quotas or fishing outside of designated areas, their vessels may be seized and fines and jail sentences can be imposed.

The immediate effect of the law will be reduce the foreign catch by about a third. The Senate Department expects to issue licenses to about 1,000 foreign vessels. The licenses will set quotas and specifying the geopgraphic area each country's ships may fish.

On the East Coast, foreigners won't be allowed to fish for cod, haddock or yellowtail flounder. In the Pacific, king carbs and shrimp will be reserved for U.S. fishermen.

American fishermen while acknowledging it will take at least five years for amy stocks to rebuild, see an opportunity for expansion.

Roy Enokson, 37, a New Bedfordman who owns two boats, is building a third, a 100-foot trawler which wil cost $750,000. "Now, with the 200-mile limit, there will be something to fish for," he said.

The nes protectionism is expected to aid the depressed U.S. seafod processing industry. Ron Tichon, whose family owns one of a dozen procesing companies in New Bedford, said his plant has operated at a third of capacity since 1970.

The fish were not available," he said. "We don't average two boats of fish a day. We could handle 10." If the 200-mile limit stimulates American fishing, his plant could operate at capacity in five years, Tichon said.

John Burt, head of the 1,000-man New Bedford Fishermen's Union, sees the new law as "a big opportunity." "The foreigners have had a free for all," he said. "When the species started to play out, our men sold their boats and came ashore. Now we're building back slowly. We'll get a better shot at our fish out there."

American seafood consumption has doubled in the last decade. More than 70 per cent is imported, creating a balance-of-trade deficit of $1.3 billion a year. The 200-mile limit could turn this around, fishermen say.

According to the National Marine Fisheries Service, 46 per cent of U.S. imported fish comes from the waters off American shores. Now that foreign competition for those fish will be reduced, American fishermen will be more likely to catch them.

"We're also going to fish more of the underrecognized species like squid, hake and mackerel," said Howard Nickerson, head of the New England Fisheries Steering Committee, a private group. "The American public is getting more seafood conscious. We can export squid to the Spaniards."

Whether the 200-mile limit is enough to change the nation from a seafood importer to a seafood exporter remains to be seen. The fishermen think it is but question whether species such as mackerel and squid should be declared in surplus and opened to foreign fishing.

However, the State Department maintains that until a market develops here, or the U.S. fishing industry organizes itself to harvest and export those species, foreign vessels may continue to fish off American shores.

Arguments are already developing over the quotas allowed to foreigners. The government is bending over backwards to accomodate foreign nations even though they have behaved very badly during the first three months of this year," said Christopher Weld, head of the National Coalition for Marine Conservation.

"The Japanese have been fishing for squid, but they've taken up 55,000 metric tons of butterfish in the process. The Rusians have been grabbing off mackerel in excess of their quotas."

American fishermen are wary of the regional councils' power to regulate them as well as the foreigners. "Some stocks are so depleted that even the remaining U.S. fishing could continue to depress them unless some regulation is applied," said William Gordon of the fisheries service.

A General Accounting Office report recently recommended limiting American fishermen's entry in certain fishing grounds. Not only commercial fishermen, but the nation's 30 million recreational fishermen could be affected by such a limitation.