Seven days a week, as dawn sneaks over the skyscrapers, lobster boats set out from a small dock wedged between a power plant and giant chemical storage tanks.

Threading their way through tugs and tankers, Boston Harbor's lobstermen are no anachronism: last year 55 boats hauled in nearly 1 million pounds, more than any other port in the country.

But this year, from Maine's granite coast to the New Jersey shore, the lobster harvest has declined drastically -- in some areas by as much as 60 percent.

Biologists fear that the thorny crustacean, symbol of New England's bounty, is threatened by overfishing. In the past two decades, lobstermen turned from single-pot fishing to trawling -- each boat laying up to 1,000 or more traps strung in lines of 20.

In Maine, the number of pots has tripled since 1967, to more than 2 million. But the state's 9,000 lobstermen are catching about the same amount -- 22 million pounds a year -- as they did two decades ago.

In Boston Harbor, even a newcomer like Tom Kearney notices a difference. Tying up his 36-foot wooden trawler, Kearney, 30, recalled the "good old days" when he bought his boat three years ago.

"It was easier to get a pound a trap on a two-day set," he said. "Now I get an average of half a pound." Using a hydraulic winch, Kearney hauls up half of his 750 pots every other day.

Three-pound lobsters, commonplace in the time of the Pilgrims, are now rare. Ninety percent of lobsters meeting the minimum size of about 1 pound are harvested each year, creating a dangerous shortage of reproducing females in coastal waters, according to state fishery experts.

A move is afoot to enact federal legislation to increase the minimum size to about 1 1/2 pounds or to 3 1/2 inches measured from the eye socket to the end of the back shell.

However, opposition from lobstermen and restaurateurs, coupled with competing state interests -- Maine lobsters take longer to grow than those in warmer southern New England waters -- have stymied such legislation.

Down the dock from Kearney, Paul Urbanus, 42, hammered at his pots, the oak-slatted and netted contraptions used since the 1880s.

"There's a need for conservation," he said. "We don't want to crowd the bottom." Urbanus runs 800 traps, a voluntary limit set by the Boston Harbor Lobsterman's Association in an effort to preserve the species and avoid a repetition of the turf wars in which lobstermen cut each other's lines and raid each other's pots.

A former auto mechanic, Urbanus said his catch is down 30 percent this year from last year. But autumn is the lobsterman's most productive season in a fishing year that normally lasts from May to November, and he cautions, "The year isn't over yet."

Even if it doesn't get better, Urbanus said he will survive.

"Maybe I won't go on a Caribbean cruise this winter," he said.

With the dockside price here at $2.50 a pound for their catch, lobstermen can average a net annual income of $40,000, Kearney said.

Beyond the bad news of the season, Boston's lobstermen have had to worry about their survival as their city has evolved from provincial capital to booming financial center of New England.

Condominiums, restaurants and boutiques have sprouted on the waterfront, crowding them off docks where their grandfathers fished.

Last year the Roman Catholic archdiocese found them the dock by the Boston Edison plant in South Boston. The utility has plans to use the lobstermen's new site as a coal storage yard, however. Again, they are faced with a move.

While coastal lobstering is suffering, deep-water lobstering, with large boats 25 to 75 miles offshore, is prospering. A new industry since the 1960s, deep-water lobstering accounts for a third of the catch. By some accounts, deep-water lobsters have reproduced enough to replenish the dwindling supply of coastal lobsters. Biologists fear, however, that as deep-water lobstering expands, coastal lobster populations could crash.

Nonethless, lobstermen, on the whole, are cautiously optimistic. This year's poor catch resulted from the blizzard of 1978, which washed thousands of young lobsters ashore, they say.

Roy Tate, executive director of the Massachusetts Lobstermen's Association, says a summer that was cooler and wetter than usual was a factor.

"When the water is cold, lobsters go into a reduced level of activity and don't come out of their burrows as they would if the water were warmer and the salinity level were up," he said.

Boston's lobstermen are hoping that this year, as last year, the catch will be saved by an Indian summer allowing them to fish as late as December.

Whatever the weather, lobstermen are philosophical about nature's cycles and the unpredictability of their secretive prey.

"It is probably just one of those years where the lobsters aren't where they normally are," Tate said. "Maybe next year will be better."