For nearly 50 years, a man named Dise has been pulling up to a Crisfield dock to sell oysters to a man named Todd.

The Dises, of Tangier Island, catch the oysters, setting sail early on frigid mornings for beds in the Pocomoke and Tangier sounds. The Todds see to it that the oysters are cleaned, shucked, packed and shipped out on time for family dinners.

This winter, the Dise is longtime waterman Dan Dise with his crew on the Castella. The Todd is Casey Todd, owner of MeTompkin Bay Oyster Company in Crisfield, though sometimes Casey’s son Josh meets the boat instead. Casey Todd, 60, has bought oysters and crabs from Dan Dise’s father and his uncles. Casey Todd’s father, I. T. Todd Jr., bought them from Dise’s grandfather. And Casey Todd’s grandfather, Ira Thompson Todd Sr., bought them from Dise’s great-grandfather.

“There is a connectedness here that goes back generations,” Casey Todd said. “And I think it’s going to go on another 50 years.”

You don’t have to go back that many years to reach a time when Todd was pessimistic. You just have to go back to 2007, when his son Josh joined the business after graduating with a business degree from Washington College. That year, nearly all of the oysters that MeTompkin shucked at its waterside operation in Crisfield came not from boats but from trailers. Two or three truckloads at a time pulled up from Louisiana with Gulf of Mexico oysters. That year, Todd said, only one waterman worked out of Crisfield, and he wasn’t catching much.

Today, 40 boats work out of Crisfield. Business has picked up so much that a local metal craftsman, Robert “Pickle” Paden, has made more than 50 new oyster dredges. Last year, Paden said, he made about 30. And those numbers don’t factor in the dredges watermen bring in for repairs.

After decades of disease and overharvesting, years of uncertainty and one truly devastating season, oysters are coming back in the Maryland part of the Chesapeake Bay. Last year, Maryland watermen harvested 422,000 bushels that brought a dockside value of $14 million — the highest in at least 15 years, according to the Maryland Department of Natural Resources. It remained a far cry from the 2 million to 3 million bushels harvested throughout the 1970s and 1980s, before oyster diseases took their toll. But it was far better than in 2002, when the harvest was only 20,000 bushels and many oystermen hung up their dredges.

The wild oyster has been on an upswing since 2011, the year Casey Todd began saying goodbye to the trailers and hello to more watermen whose names he’s known for five decades. The last trailers came from the Gulf in 2011. After that, Louisiana faced an oyster crisis of its own, courtesy of Hurricane Katrina and the Deepwater Horizon oil spill. Now, Louisiana shucking houses are importing Chesapeake Bay oysters.

Todd never liked relying on the trailers, but he did what he had to do to keep his shucking house open. Many others went out of business. Now, Todd says, he’s happy to write checks to families he knows.

Scientists attribute the recent success of wild oysters in the Chesapeake to an excellent spat set in 2010 and favorable weather conditions. But Todd thinks it’s something else: Today’s oysters have learned to live around the devastating oyster diseases of the past. They are survivors.

That faith prompted Todd to double down on oysters. At his shucking house along Tangier Sound, a dozen or so men shuck between 200 and 300 bushels a day from the public wild fishery. Two years ago, he also started an aquaculture operation on 400 acres of leased bottom in the Big Annamessex River. With oyster larvae from the University of Maryland Horn Point Laboratory and shells from his shucking operation, Todd has plans to grow oysters. He hasn’t harvested any oysters from the operation yet, and he’s not sure when it will be profitable.

“This is a lifetime project,” Todd said.

Todd isn’t kidding about that. He has photographs from 1982 with Don “Mutt” Meritt, now director of the Horn Point Laboratory, and Don Webster, an aquaculture specialist with Maryland Sea Grant. In them, Meritt is trying to teach Todd how to set oysters on shell in large tanks. One photo features the “spatmobile,” a vehicle that delivered oyster spat to the tanks.

The technology didn’t have much application in those days; leasing Bay bottom for private oyster reefs was illegal in nearly every Maryland county, and watermen opposed attempts to change the law. Plus, disease was so rampant then that many oysters did not live.

But by 2010, the law was changed, and the door was opened. By then, Stan Allen at the Virginia Institute of Marine Science had bred a disease-resistant oyster in his lab, and the wild populations were showing resilience.

When the tide turned, Webster, Meritt and Todd were all still around. Thirty years after they first tried to set oysters in MeTompkin’s tanks with the spatmobile, the trio have gotten to witness a genuine aquaculture operation there.

“He was one of the first people in line the day leasing opened in 2010,” Webster said. “The Todd family has been in the seafood business for multiple generations and we look forward to having them here for many more to come.”

The aquaculture operation is also a hedge against nature, in case the wild oysters once again encounter trouble. Todd remembers a story his father told him about a man on the Delaware Bay who went by the name of Whippy Hand. Whippy harvested oysters, and Campbell’s Soup was his main customer. In the 1950s, the company wanted to integrate its suppliers and offered to buy Whippy’s operation for several million dollars. He said no. Several years later, the oyster parasite MSX hit, and Whippy Hand was out of business.

The lesson of Whippy Hand is never to become complacent. There seems little risk of that with the Todds, hardy Scotsmen who have long lived around the waters of the Chesapeake Bay.

Casey Todd’s father was the last boy born on Holland Island. I. T. Todd Jr. founded MeTompkin and worked there until he retired in 2010, at the age of 92. He died in 2013.

I. T.’s father worked in the seafood business in Crisfield, where he’d moved his family in the 1920s after it became clear that Holland Island was sinking into the Bay. But Todd Sr. wanted something different for his son; he sent him to college to earn a degree in accounting. After that, young I. T. was drafted and fought in World War II. He came home and started MeTompkin.

Like his own father, I. T. encouraged Casey Todd to find something else, something easier. Todd earned a law degree. But when he graduated, he went to work for his father.

Casey Todd gave his son, Josh, the same advice. Josh didn’t listen, either, and so four generations of Todds have stayed in the seafood business in Crisfield. Casey’s brother, Mike Todd, also works for MeTompkin. He focuses on the soft-shell crab side of the business.

I. T. was right. It has been hard. Especially in 2012, when Superstorm Sandy’s winds threw Crisfield’s town dock into MeTompkin’s plant and did $150,000 worth of damage. Employees rebuilt the plant and were back in business before long.

Yet, Todd never doubts he made the right decisions — both to stay at MeTompkin, and to invest in its future.

“The world could use more oyster people,” Casey Todd said. “We don’t need any more lawyers.”