There were television cameras to the left of him, reporters at his heels and a big fish on his line. In the 10,000-year history of the Chesapeake Bay, few fish had been yanked from the water into such celebrity.

"It's bigger than the prince," said Maryland Gov. Harry Hughes, appraising the 14-pound blue-fish that, coincidentally, was the first caught during a state-sponsored public relations outing last week to celebrate the bay's bounty.

Maryland's Office of Seafood Marketing sponsors the "Day on the Bay" each year for dozens of travel and outdoor writers to remind them how lovely the bay looks from a fishing boat and how delicious is its seafood, especially when it's free.

This year's promotion was especially earnest because it came only two days after the first reports of a massive, $27 million study of the bay were published that point to serious pollution problems and dwindling marine life.

The six-year Environmental Protection Agency study of the bay uncovered evidence that nitrogen and phosphorous wastes, most coming from runoff from farm fields and construction lots, are suffocating the upper part of the bay. Aquatic grasses, which are a crucial habitat for much of the bay's wildfowl, have declined markedly in the last 10 years.

The same decline is evident in commercial-catch figures for striped bass, the most coveted fish in the bay. In 1973, fishermen caught 7.3 million pounds. In 1980 the catch had dropped to 2.5 million pounds.

"If we wait 20 more years . . . it may be too late to reverse the situation," Kent S. Price, a University of Delaware marine biologist who worked on the EPA study, said last week.

Maryland's seafood officials are more aware than most that the bay has its problems. In the past, they have led the call for more funds to protect the Cheseapeake. But this week, while trying to show off the bay's best profile, they went on the offensive to counter what many felt were overly pessimistic predictions.

"I am pleased to report that the productive shellfish-growing areas of Maryland are now among the cleanest in the nation," said Hughes at a dinner that night before the fishing outing. "In spite of periodic laymen's predictions of poor oyster harvests, Maryland waters have been able to maintain an oyster yield in excess of two million bushels per year."

The state of the bay involves a lot more than pride. An estimated 25,000 people in Maryland have jobs directly related to the $130 million a year seafood industry. Bait sellers, charter boat captains, marina operators -- all depend on the bay for at least part of their livelihood.

Because stakes are so high, the recent decline in fish catches has provoked general alarm and finger pointing. Scientists are blaming coal-fired electric power plants and automobiles, for example, for the buildup of suspected cancer-causing substances in sediments of the upper bay. Sport fishermen and charter boat captains, disappointed by this summer's bluefish catch, are complaining about a new, more efficient net-fishing technique used by a commercial fish company.

Fass Brothers, a Hampton, Va., company, began this spring using a circle gill-net method that captures whole schools of fish, particularly bluefish. Sport fishermen asked the Virginia Marine Resource Commission to ban the method, which has already been outlawed in Florida and by the South Atlantic Fisheries Council for offshore fishing.

Last week, VMRC officials refused to prohibit the commercial method, noting that such a ban could harm the seafood industry. But Robert Craft of the VMRC did say the circle net technique "has the potential of being a major problem if it is extended to more people and other fish."

The bluefish catch this year has also been affected by heavy June rains that have caused unusual amounts of fresh water to flow into the middle bay. Last week, charter boat captains taking Hughes and sports reporters out for a day of fishing warned that many of the bluefish had moved farther south to avoid the fresh-water runoff.

The warning proved accurate. Although the governor caught his bluefish just minutes after dropping his line, it was the last he would catch all day. His wife, Patricia, hooked another one a few hours later but lost it before it could be reeled to the boat. Anglers on 15 other boats involved in the "Day on the Bay" outing had fishing luck ranging from mediocre to poor.

But with the sun shining brightly and the sky an almost cloudless blue, it was as pleasant a day as any not to catch fish.