Maryland officials, citing a seven-year reproductive tailspin for the state fish, striped bass, are invoking a ban on all fishing for stripers in spawning waters of the Chesapeake Bay from March 15 through June 1.

Louis Phipps, deputy secretary of the state Department of Natural Resources, invoked emergency powers to outlaw fishing in all waters at the head of the bay north of Worton Point and in waters out to the mouths of the Chester, Choptank, Nanticoke, Wicomico, Pocomoke. Transquaking, Manokin and Patuxent rivers and in parts of the Potomac.

Commercial fishermen, stunned by the sudden decision, say it will cost them millions of dollars. They intend to fight the ban in court and in the state legislature.

About 1,300 Marylanders hold commercial fishing licenses, and according to Larry Simms, head of the Watermen's Association, almost all of them regard the spring as the time "we make our living."

The Chesapeake is a key spawning ground for stripers, or rockfish, as they are known locally.Brood fish come from north and south to lay their eggs in brackish waters at the head of the bay or in its tributaries.

Said Simms, "The markets are glutted with rock now. They're catching them in the Carolinas and in New York and off New Jersey. They're on their way here to spawn."

Rockfish have been in decline in the bay for several years, since the effect of a huge spawn in 1970 started to wear off. There hasn't been another top spawning year since the catches have declined steadily over the last several years.

The commercial fishermen contend it's water quality, not fishing pressure, that's hurting the prized eating fish. The scientists agree, in part, but maintain that they've got to do what they can to keep the fish from disappearing altogether.

Says Ben Florence, DNR biologist and rockfish specialist, "We still have a substantial spawning population. Our concern is with favorable spawning conditions. But we need to protect the fish we've got left so they'll still be here if and when we have proper spawning conditions."

According to DNR figures, the commercial rockfish catch has dropped from 5 million pounds in 1973 to 1.2 million in 1977. Florence said 86 percent of that harvest comes between February and May, mostly in March and April.

The commercial fishermen dispute the totals, contending that for a variety of reasons not all fish taken are reported to authorities.

Anyone who has fished for rock regularly over the last 10 years knows there is trouble.

The commercial fishermen are angriest, they say, because the ban was imposed without warning last weekend. "Our people already have bought their equipment for the spring. They've invested $5,000 to $20,000 apiece," said Simms.

He said Phipps has estimated the ban will cost watermen $1 million. "We'd say you could more than triple that at dockside, not counting related industries."

Phipps took the action under authority granted DNR by the legislature in 1966 to regulate fishing for stripers in spawning areas. He resorted to emergency powers, according to sources, in order to bypass the 45-day waiting period necessary for public comment on new regulations.

The emergency measures must be approved by a state administrative executive legislative review committee, which has slated a meeting at 7 p.m. Thursday at the Legislative Services Building in Annapolis.

The commercial netters will fight the move there, Simms said, and also will seek a court injunction preventing the ban.

The ban would extend only to the spawning areas, and fishing would still be permitted in the main body of the bay.

That doesn't do the netters any good, said Simms. "We don't have the equipment to fish the open bay."

State officials and the Watermen's Association met Wednesday to try to iron out differences. Both sides claim they expressed a willingness to compromise, but that the other side was intransigent.

Says Simms: "Our view is it's the water quality and the shape the fish are in that's to blame. What good is it to take away our livelihood if other states are going to take the fish and other states are going to poison them?"

Says Phipps, "It's a drastic step, but we don't know any other way. It's time that drastic steps be taken."