The Chesapeake Bay has always been considered worth fighting over. The 10,000-year-old puddle, left behind by the last ice age, has been plundered by scalawags from Bluebeard to the British Navy.

This summer was no exception. From the middle of May, when some commercial fishing boats from Florida dropped their nets into the Virginia side of the bay to capture whole schools of bluefish, until last week when that fishing method was restricted by state regulation, there have been enough water wars to keep a team of mediators working full time.

The major fights have been over fishing rights. In one clash between Maryland and Virginia oystermen, two brothers from Crisfield were shot by four men in a Virginia-registered boat. Other squabbles, between biologists, environmentalists and industrial users have been less violent, but equally emotional.

The most pleasant disagreement has concerned the real or imagined existence of Chessie, which witnesses have described as a dark-colored, 40-foot-long something or other with a head the size of a football and a body as thick as a human thigh. In May, a 40-year-old computer salesman videotaped Chessie as it snaked through the bay near Kent Island.

The Enigma Project, a Baltimore-based group which studies paranormal events, claimed the film was authentic. But in August a group of Smithsonian Institution scientists judged the tape too blurred for any accurate identification.

"We and they don't know what it is, but we do know it is something," said Michael Frizzel, a researcher with Enigma.

Sport fishermen and charter boat captains had more time than they would have liked this summer to talk about Chessie. Fishing was generally lousy. Rockfish, the premier sport fish of the bay just a few years ago, were scarcer than good news again this summer. To make matters much worse, the normally plentiful bluefish disappeared for weeks at a time.

Given those circumstances, the appearance in May of four Florida fishing boats, using a controversial bluefish netting technique in Virginia waters, created an uproar.

"If we can't catch bluefish, we're out of business," said Bob Stoner of the Northern Neck Charter Boat Association two weeks ago at a public hearing in Newport News, Va., that considered imposing restrictions on commercial fishermen.

Sport fishermen objected to the gill-net encirclement technique because they considered it too effective. After airplanes have located a school of bluefish, nets up to 1,500 feet long are dropped to the bottom of the bay, then drawn into a circle to trap the entire school. Fishermen complained that the technique depleted breeding stock of bluefish, spot, trout and rockfish. This summer the Florida boats, working for a Virginia company, caught 760,000 pounds of bluefish, which represented about a third of the total commercial bluefish catch in 1981.

The Virginia Marine Resources Commission initially voted in July against enacting any restrictions on the gill-netting technique. But two days later, after a storm of protest from sport fishermen and pressure from Virginia Gov. Charles S. Robb, the commission reversed itself and adopted emergency restrictions.

Last week, the commission met again and imposed permanent restrictions on the fishing technique. The new regulations allow gill nets to be used only if they are 200 feet apart and go no deeper than 330 inches. James Douglas Jr., commission chairman, resigned two days after the final regulations were announced.

"He got himself caught in some fishing nets," said one official with the commission.

Randall Franklin Burke, 25, and his brother Ronald William Burke, 21, got themselves caught in a cross fire between a court order opening Virginia waters to Maryland crabbers and some Virginia watermen who didn't approve of lifting that century-old ban.

The two Crisfield men were half a mile within the Maryland border, after a fishing trip in Virginia, when they were ambushed by another boat carrying four men armed with rifles and a shotgun. Randall Burke was wounded in the back and arms and Ronald Burke in the right arm and face. Both were hospitalized, but released the same day.

While fishermen were shooting and shouting this summer, scientists were probing and measuring the general health of the bay. The results were not encouraging.

A $27 million federal study showed that America's largest estuary was suffering from long-term pollution and dwindling marine life. Scientists blamed agricultural runoff from farms, sewage from increased population around the bay and industrial pollution for declines in several species of fish and ducks.

Lest we leave you with a bitter taste, here is something positive reported by L. Eugene Cronin, director of the Chesapeake Research Consortium in Annapolis, at the 46th North American Wildlife and Natural Resources Conference held in Washington last year.

"The bay has long been fractioned between states and among federal regions and districts. Now, it is increasingly regarded by the public, studied by scientists, and managed by agencies and by regional cooperative bodies, as a single physical, chemical and biological system, with all parts inextricably linked."