Baby oyster boom spawns a mystery The bay: A bonanza of baby oysters off Kent Island puzzles bay watchers. "We don't have a clue," says an expert.

May 12, 1998|By Heather Dewar | Heather Dewar,SUN STAFF

Lawrence Murphy has been a waterman for 28 of the Chesapeake Bay's leanest years, but he still believes in a generous and forgiving Mother Nature. And this spring in the waters of Eastern Bay near Kent Island, he has been raking in a unique harvest that seems to prove him right:

Baby oysters in amazing and mysterious abundance -- so many that 800 million of them are being gathered to help Maryland's Department of Natural Resources re-establish failing oyster bars on the Western Shore.

If the youngsters take hold, the transplanted colonies could contribute to a potential turnaround for the struggling fishery and improve the overall health of the bay.

Scientists can't explain the stupendous outpouring of oysters spawned in the waters of Eastern Bay and a few other hot spots last summer. But they're delighted with Eastern Bay's spring bonanza of thumbnail-sized oysters cemented to old shells -- about 5,000 in every bushel, compared to a good year's rate of 1,000 "spat" per bushel and a bad year's rate of zero.

"It's a tremendous spat set unlike anything we've seen for the past 30 years," said biologist Chris Judy, acting director of the Maryland Department of Natural Resource's oyster program. "Some watermen say they've never seen anything like it in their lives.

"And why is it happening? We don't have a clue."

Murphy thinks he does. "I think Mother Nature is saying if we take care of her, she's going to keep on taking care of us," said the Tilghman Island native, who is helping DNR transfer young oysters from Eastern Bay to the waters off Anne Arundel County. "It seems like every year is a little better than the last."

Oysters were once the mainstay of the bay's seafood industry, with an average harvest of 2.2 million bushels a year in the 1970s. But diseases have ravaged the bay's shellfish beds since 1987, and in 1994 the harvest fell to an all-time low of about 80,000 bushels.

That spelled hardship not only for the watermen, but for the health of the Chesapeake. Oysters provide food and shelter for hundreds of bay creatures, including many varieties of commercially valuable fish.

And they play a vital role in keeping the bay clean, since a healthy adult oyster can filter 50 gallons of water a day. A %J hundred years ago, scientists think oysters were abundant enough to filter the bay's total volume of water in three to six days; now it takes nearly a year.

Harvests have been creeping upward for the past four years, to 260,000 bushels in the season that ended Mar. 31. Scientists aren't sure what has changed, but think the increase may be due to the offspring of disease-resistant oysters reaching market size.

But reproduction rates have been erratic -- as low as a bay-wide average of only two spat per bushel in 1996. Last year the Chesapeake's average shot up to 277 per bushel, largely based on Eastern Bay's big output, though some areas produced no spat at all.

The water's relatively low salinity is the main factor in oysters' spawning success, Judy said, but Eastern Bay's salinity hasn't varied much for the past three years, "so there's got to be something else going on that we don't know about."

This year, the state is spending $570,000 raised from watermen's license fees to supplement six commercial oyster bars between the Chesapeake Bay Bridge and Herring Bay in southern Anne Arundel County. The transplants involve about 500,000 bushels of young oysters attached to old shells from Eastern Bay.

If the young oysters beat disease, many of them will end up as food for fish and waterfowl. Those that survive "should be ready for harvest in two or three or four years, and they'll provide ecological benefits in the meantime," Judy said.

Another 800 bushels are to be planted today at Horn Point Bar, a Severn River oyster bed that has long been off-limits because of pollution, with the sole aim of helping to restore the river's water quality.

With the assistance of the Chesapeake Bay Foundation and other private groups, DNR is hoping to do more oyster reseeding to restore the environment.

"This is really about jump-starting the recovery of the oyster population," said Thomas V. Grasso, the foundation's Maryland director. "It means a healthier bay habitat overall."

Aboard the Nora W, Murphy's World War II-vintage workboat, crewmen Kyle Wood and Greg Opie used a heavy steel dredge to rake up spat-encrusted oyster shells from the shallow waters of Eastern Bay. Before dawn yesterday, the shells covered the 83-footer's foredeck, piled to just below the pilot house windshield.

By midmorning, Murphy had swung the Nora W's bow into the wind over Hackett Point, an oyster bar just off the Severn's mouth. Wood and Opie used a fire hose to blast the stacked shells with a jet of seawater, washing them over the side of the boat.

At 88 cents a bushel and $1 a mile to the Nora W's crew, the seeding work is a good deal, said Opie. "It's easy work and it does us some good," he said. "There's more oysters for us in a few years' time."

Pub Date: 5/12/98

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