The Potomac River Fisheries Commission today ordered a sharp curtailment of sport and commercial fishing for rockfish on the Potomac River in 1984 in an effort to replenish dwindling stocks of the fish.

The multi-jurisdictional commission's action ended three years of dispute over regulations designed to promote the spawning of rockfish, also known as striped bass. The commission held open the possibility of extending the restrictions beyond 1984, depending on how well the fish recover.

The decision comes as a compromise for marine ecologists who want an absolute ban, on the one hand, and commerical fishing interests fighting regulation of their livelihood, on the other.

The new restrictions will bar the use of gill nets on the Potomac from Jan. 1 to Feb. 15 and from April 1 to May 31. It will also prohibit keeping rockfish caught by hook during those same periods.

In addition, the commission voted to halve the permissable width of gill nets from 1,200 to 600 feet and enlarge their mesh to 3 3/4 inches. Currently, the mesh is allowed to be 2 1/2- to 3 1/2-inches, depending on the season. A gill net is set upright in the water and is designed to catch fish by entangling their gills in the mesh.

The commission also declared a moratorium on licenses for gill nets, effectively holding their number at the current total during the times next year when gill-netting is allowed. This year, 186 individuals were licensed to set up gill nets.

The catch of rockfish on the Potomac has dwindled from 1.5 million in 1965 to 136,053 last year.

The net restrictions came as a partial victory for scientists at the Maryland Department of Natural Resources and the Virginia Institute of Marine Sciences, who favored closing the river entirely to rockfishing next season.

But the six-week "window" beginning Feb. 15 was a significant concession to watermen, according to Kirby A. Carpenter, executive secretary of the commission, allowing them to drop nets as the fish head up the river to spawn.

Still, it was an angry group of fishermen from the Dumfries and Cherry Hill area of Virginia that stamped out of the commission meeting today, complaining that the backbone of their livelihood, as one said, "has just been shot to hell."

"We're going to have to sell dope, that's all," said William Allen Dent III, who's caught rockfish all but six of his 31 years. Robert N. Reamy Jr., president of Nomini Seafood Co., a Montross, Va., wholesale packing company, said his business relies heavily on rockfish and he expects to be hit hard next year. "And I just built a new factory," he said.

Joe Fletcher, an owner of Fletcher's Boat House in Washington, D.C., a spot prized for sport rockfishing, said the regulations could put a crimp on his business.

"It ain't going to help business," he said. " 'Course, they got to enforce it."