The shrimp boats are a-coming -- no, make that the shrimp boats have arrived -- carrying the venerated recipe for American legislative gumbo.

It works this way:

Hire a high-powered Washington law firm to plead your case. Mix with market research to show the shrimp industry nearing collapse.

Stir with a fancy reception, featuring heaps of succulent shrimp and ample drink for legislators who may rescue you. Top off with a congressman, who will introduce a bill and hold quick hearings.

Following that recipe, a newly formed Shrimp Harvesters Coalition of the Gulf and South Atlantic States came to town this week to promote the American Shrimp Industry Development Act.

The bill, examined yesterday at a House Merchant Marine Subcommittee hearing, was confected by Washington lawyer-lobbyist Leigh S. Ratiner and an old friend, Rep. John B. Breaux (D-La.), who happens to be chairman of the panel.

The shrimpers' story is that rising fuel and labor costs, in combination with lower-priced imports of shrimp, are devastating the American shrimping fleet based in the southeastern and gulf states.

What they want from Congress, when the political currents seem to be running in an opposite direction, is protection of a degree that few industries have dared seek in recent years.

The bill would impose a five-year quota on shrimp imports, then tax them with a 30 percent ad valorem levy. A fourth of the tariff money would provide low-interest loans to start shrimp harvester cooperatives to increase marketing clout. Marketing boards would be set up to promote the eating of shrimp.

Although prices keep shrimp beyond the reach of the average American consumer, the industry is a big-time contributor to the economy. It employs some 34,000 people in harvesting and processing and puts an estimated $1.4 billion into the national economy.

The United States is the world's largest consumer of shrimp, yet American fishermen produce only about half of the supply. The rest, more than $700 million worth each year, comes from foreign fleets.

The foreign catch now enters the United States without restrictions, with Mexico, the chief foreign supplier, reaping the biggest benefits, mostly because of lower fuel and labor costs.

Al Silchenstedt, president of the coalition, told Breaux' subcommittee that the U.S. industry is on the verge of bankruptcy if Congress doesn't intervene.

Executives of shrimp processing firms opposed the coalition's plan, but the strongest objections came from the Reagan adminstration, which argued that the proposal represents unsavory and dangerous trade restrictions.

Breaux said he would continue to try to persuade Congress that the shrimpers need help quickly.

The shrimp, you might say, has become a prawn in a political fight.