Capt. Mike Sullivan has come up with a new wrinkle on fishing shows _ a seminar on how to fish the Chesapeake Bay, running two days the last weekend of February in downtown Washington.

Sullivan, who runs the charter boat Miss Dolly out of Chesapeake Beach when he isn't running his printing business in Largo, is convinced that he and other charter skippers need to spread the word about what they do and how they do it.

Some of his colleagues think he's nuts. One captain told Sullivan he was digging his own grave. "He said if we tell everybody how to fish, then they won't need us," said Sullivan. "I told him I don't possess that much knowledge. If I gave it all away, I still couldn't hurt myself.

"And I asked him if we knew everything, how come we learn something new every time we go out there?"

The seminar will be from 7 to 11 p.m. on February 27 and noon to 4 on February 28, at the Holiday Inn at Sixth and C streets SW. The $2.50 admission covers both days, which means that if you learn anything at all, you've stolen it.

Sullivan has about a dozen captains scheduled to speak at the Friday-evening session, among them Ed Darwin on rockfishing in the Upper Bay; Sullivan on reading the depth-finder; Charles Mariner on bottom- fishing Tangier Sound; Monty Webb on black drum fishing at Cape Charles; Mark Middleton on spring trolling for big rockfish, and Mopy Barber on chumming for blues off Point Lookout.

At the Saturday session Sullivan plans to have about 60 Bay captains on hand to answer specific questions about fishing tactics, rigging and techniques. Also, he said, there will be tackle displays by manufacturers, booths where bucktails and rubber eel lures are made and other displays.

It's all an experiment, as are about half the things Sullivan does when he's fishing. He's an avowed risk-taker. If the seminar's a smashing success, he's pledged to donate the profits to Children's Hospital.

"We're not trying to make any money," he said. "We're just trying to teach the public about Bay fishing, with the hope that by doing it, the captains can enhance their business." For details call 336-1710.