Waterman Bubby Powley, 66, crabs before sunrise on the Chesapeake Bay. He’s been fishing for more than 40 years. (Linda Davidson/The Washington Post)

At 4:41 a.m., Bubby Powley looked at his watch, looked at the thin, pink glow to the east, and looked at the dark water sliding past his boat. According to Maryland state law, he was allowed to start catching crabs exactly one hour before sunrise, and that was right . . . about . . .

“Now. Dontcha think, Monroe?” Powley said, hitting a lever on a boom that lifted his first batch of the day from the Chesapeake Bay. The sprightly 66-year-old swung the basket inboard, where his culler of 42 years, Monroe Dorsey, 68, a slim cigar clenched under his white mustache, dumped a few dozen wriggling crustaceans into a fiberglass basin.

It was a pretty good haul in what so far has been a very good crab harvest. Dorsey measured male after male with a plastic caliper and tossed those of five inches or more into one of the six and a half bushels Powley would sell later that day to a wholesaler.

The summer is getting off to a promising start along America’s biggest estuary — the center of a beleaguered, multibillion-dollar commercial fishery. Scientists are predicting a robust blue crab season, with an annual survey showing big numbers of crustaceans beginning their annual south-to-north march across the bay’s floor. Fishermen report a marked improvement in water quality. And with every haul of his basket, Powley has to clear his rig of huge clumps of eelgrass, a vital marker of the ecosystem’s health that had been missing for years.

“It’s a little too soon to go overboard and declare victory,” said Bill Goldsborough of the Chesapeake Bay Foundation, “but it’s a positive sign.”

But out on the water an hour before dawn, it’s hard for the Chesapeake’s weathered and wary watermen to exult. After decades of declining catches, reams of new regulations and endless market fluctuations, those who still pull their living from the bay know that every silver lining has its cloud.

“We’ll know whether it’s a good year in November [when the season ends],” said Powley, who has been fishing off Hoopers Island in Dorchester County for more than 40 years, just as his father, grandfather and great-grandfather did.

He has seen a season start out with the traps and trotlines brimming with crabs only to peter out in the doldrums of midsummer, as it did in 2012. Location can be key, as migrating crabs congregate in some nooks of the bay and leave others empty of commercial quantities. The best years, watermen say, are when the Chesapeake has a big harvest and other parts of the country don’t.

“Everybody’s got crabs this year, from New York right on down to Georgia,” said John Buchanan, a lifelong fisherman who crabs on the Tred Avon River near Oxford, Md.

Monroe Dorsey measures freshly caught blue crabs to see if they are large enough to harvest. State officials say crabs should be abundant this year, but the strong supply is already driving down the price. (Linda Davidson/The Washington Post)

Already, they can feel the pinch that bites harder than any crab claw: When the catch goes up, the price goes down. Full-timers are finding it easy to fill bushel after bushel. And part-timers, drawn by reports of easy pickings, are trailering in boats and leaving the wholesale docks groaning with crabs. At the beginning of June, Powley was making $100 for each bushel of No. 1 males. Within three days, the price fell to $80. A week after that, $70.

“Any waterman will tell you it’s not what you catch, it’s what you make,” said Buchanan, who estimates that 90 percent of the boats he sees are part-time license-holders working weekends and vacations. The boat tied up two slips from his belongs to a Talbot County deputy sheriff.

“They come in for the gravy and still have a job to fall back on,” he said. “The full-timer waterman, though — that’s getting less and less.”

The lean years have taken a toll on Chesapeake fishermen, according to Tom Horton, an environmental studies instructor at Salisbury University and a frequent chronicler of the bay’s signature waterman culture. He estimates that their numbers have fallen from 10,000 or more in the 1990s to fewer than 3,000 who are active today.

Overfishing of crabs, oysters and rockfish squeezed out many. And while the massive multi-state effort to restore those fisheries is showing signs of success, its restrictions — on the hours they can fish and the amounts they can land — have chased plenty of watermen to other jobs.

“The people I know who still make a full-time living off the water are the ones who thank God every day they have a wife who is a nurse at the hospital,” Horton said.

Powley, whose own wife worked in the Dorchester County Clerk’s Office for years, said he’s grateful for the long career he has had on the back of the Maybe Baby, his 42-foot Chesapeake work boat. For four decades, he ran crab pots, the high-capacity wire cages that could produce 150 bushels a morning in the days before restrictions.

Now semi-retired, he and Dorsey meet at the dock every morning at 3:30 and crab for nine hours — the maximum allowed by law — with three 2,500-foot trotlines, a piece of bait tied every six feet.

“It gets in your blood,” he said, a dark silhouette in a white bib as the sky grew rosy behind him. “I still love watching the sun come up every morning.”

He tweaked the vertical tiller at the side of his boat as he steered along his middle trotline. In the water, the thin cord rose from the five-foot bottom. The crabs zipped by as pale blurs, clinging fatally to their hunk of chicken or cow lip until they were knocked into the basket.

Monroe Dorsey releases undersized blue crabs from Bubby Powley’s boat. The two have fished together for 42 years. (Linda Davidson/The Washington Post)

At the end of the line, Powley hoisted the basket, dumped it and steered for the buoy that marked the next run. Dorsey sorted the catch into Jimmies (males), sooks (females) and peelers (the molting “soft-shell” crabs they sell for 75 cents apiece). Those too small went back over the side.

The big ones can deliver a nip even through his neoprene gloves. “When you been at it as long as I have, you don’t pay it no mind,” he said, shaking another tenacious Jimmy from his finger.

On July 15, when the size limit shifts by a quarter-inch, Dorsey will pull out the 5.25-inch caliper. In October, the workday will expand by an hour. It takes 26 clauses to detail the hours and dates governing legal crabbing through the season.

“It’s all so regulated, half the time the [Department of Natural Resources officers] don’t know the rules — they have to call Annapolis,” Powley said.

There is a grudging acquiescence to the tight controls that watermen face in the modern age. They complain but comply, assuming that no one understands the bay more than those who spend their lives on it. Some occasionally credit “management” with making things better.

“The water is as clear as I’ve seen it,” said Nick Crook, a 29-year-old waterman who lives on Kent Island, Md. “I think the pollution controls are having a positive effect.”

But generally, commercial fishermen attribute the ebb and flow of the animal populations they chase to natural cycles. They tend to dismiss the predictive power of the winter crab survey conducted by the state. Powley argues that the sea grass is back because of the power dredging for oysters they allow near Hoopers Island.

When Dorsey finished his sorting, he would light another cigar and step across the boat to work on the next day’s bait. Each case of beef lips has to be packed in salt to brine overnight. Every afternoon, he and Powley spend three more hours stripping the lines of old bait and tying on another 1,300 or so fresh chunks.

A case of cow lips is $135, giving him two days of bait per line. Fourteen gallons of diesel runs about $35. In all, it cost Powley about $300 to pull away from the dock that morning, not counting insurance, his crab license and the $18,000 he recently spent to resurface the bottom of the Maybe Baby.

Seafood vendor Derek Hall, right, helps Bubby Powley unload nine bushels of blue crabs. Although watermen are making less per bushel, they are able to round out their year with other catches. (Linda Davidson/The Washington Post)

After tying up, Powley sold his six bushels of big males, three bushels of culls (skinnier males destined for the picking house) and two dozen peelers for a take of about $650.

“It’s a lot of work, and it seems like not as many people are willing to do it full-time,” Powley said as he picked sodden clumps of grass from his net.

That sea grass used to float in patches “by the acre” when Powley started out crabbing with his father. He’s glad to see it back, even though it means more work cleaning his gear. The grass provides a critical nursing habitat for baby crabs, and its return is a sign of a recovering bay and, hopefully, a more stable fishery.

Two new crab-processing plants have opened this season on the Eastern Shore, according to Bill Sieling of the Chesapeake Bay Seafood Industries Association. And although watermen are making less per bushel of crabs, they are increasingly able to round out their year with other catches, including oysters in the fall and rockfish (striped bass), once banned from being fished in the bay. As Powley crabbed on the Honga River, his brother was texting him photos of the menhaden he was catching in the Patuxent River.

Crook, the waterman who lives on Kent Island, is making such good money from a growing market in soft-shell clams that he has yet to bring out his crab pots. Each day, he dispatches up to 15 bushels of clams to a wholesaler in a refrigerated truck. They are in Boston by 6 a.m. and fetch $80 to $100 a bushel.

“It’s all a balancing act. You’ve got to see what you can make the most money at,” said Crook, whose father has already switched to crabbing.

Still, however encouraging the future of fishing might be, Powley knows that crabs and clams are unreliable creatures. His own son did not become the family’s fifth generation of watermen. Instead, he is president of a German-based filter manufacturer in Cambridge, Md.

“Looks like I’ll be the last one,” Powley said. “I sent him to college.”