Maryland Gov. Harry R. Hughes is asking Virginia state officials to halt the incursion of Florida fishing boats into the lower Chesapeake Bay before the bay's dwindling bluefish population is depleted.

In a letter sent Friday to Virginia Gov. Charles S. Robb, Hughes warned that Maryland charter boat operators and recreational fishermen were seeing "a drastic decline in the number of bluefish caught in Maryland waters."

Hughes said the Florida boats, using sophisticated ocean-fishing techniques that include the use of huge nets, had already caught 545,000 pounds of fish in the lower Chesapeake this year. Maryland regulations ban such net fishing, but without a similar Virginia regulation the Florida fishermen are snaring entire schools of bluefish before they ever reach Maryland waters, Maryland officials said.

Robb's staff chief, David McCloud, said yesterday the Virginia governor had not officially received Hughes' letter but would have a reply shortly. However, Bill Bonds, a Virginia fisherman who serves on Robb's task force studying the problem, accused Robb of "sitting on his hands and doing nothing."

"We've got to have some action," said Bonds, who directs the Smith Point Charter Boat Association. He urged Virginia's Maritime Resources Commissioner, James E. Douglas, to use his emergency powers to stop the Florida boats from entering the Chesapeake at Virginia.

James B. Coulter, Maryland's natural resources department secretary, said the problem was that new European markets for bluefish had encouraged Florida fishermen to take their sophisticated ocean fishing techniques into the Virginia portion of the Chesapeake.

The Florida fishermen use spotter planes to track large schools of bluefish from the air, before the boats move in to drop 40-foot-deep "gill" nets into the water. Smaller motor boats then herd the fish into the nets. "This is something like catching fish in a bowling lane," Coulter said. "It cleans up everything."

Courts have struck down state laws reserving fishing rights to state residents, but states still are allowed to regulate the type of fishing equipment used.

The group of Virginia charter boat captains are urging local counties to pass resolutions to pressure Robb and Douglas to ban gill net fishing in Virginia. Bonds said he may soon begin circulating a petition urging a ban.

Coulter said Maryland's watermen need the restriction both for economic and conservation reasons. "It leaves some fish for the next generation," he said.