The Supreme Court, citing the potential "balkanization" of the American fishing industry through state residency requirements yesterday struck down a Virginia law that barred nonresidents from taking menhaden from the Chesapeake Bay.

The court was unanimous in over-turning the 1975 law that also prohibited foreign-owned U.S. corporations from fishing within the three-mile ocean limit or in the bay.

"A number of coastal states have discriminatory fisheries laws, and with all natural resources becoming increasingly scarce and more valuable, more such restrictions would be a likely prospect, as both protective and retaliatory measures," the court said in a decision written by Justice Thur-good Marshall.

Justices William H. Rehnquist and Lewis F. Powell Jr. concurred in the judgment but dissented from the breadth of majority's opinion.

"Each state's fishermen eventually might be effectively limited to working in the territorial waters of their residence . . . Such proliferation of residency requirements for commercial fishermen would create precisely the sort of balkanization of interstate commercial activity which the Constitution was intended to prevent," the court said.

The suit against Virginia was filed by Seacoast Products Inc. and two of its subsidiaries. The company was taken over by a British corporation in 1973, an action that subsequently was approved by the federal government.

Seacoast's captains, crews and shore workers are almost all U.S. citizens and the company is solely engaged in catching and processing menhaden, an inedible but commercially valuable fish that is turned into oil, fish meal and animal food. Seacoast's ships hold federal fishing licenses.

Two menhaden, a prolific member of the herring family, constituted 44 per cent of the total commercial catch by U.S.fishing craft in 1975.