Unlocking secrets of bay's blue crab

In a basement laboratory tucked amid the tourist attractions of Baltimore's Inner Harbor, two Israeli-born scientists are unlocking the mysteries of the Chesapeake Bay blue crab.

Over the past five years, Yonathan Zohar and Odi Zmora have spent most of their waking hours poring over tanks filled with the snapping crustaceans and their tiny offspring at a University of Maryland lab on Pratt Street. They feed the crabs homemade algae tailored to their life stage. The researchers control the water temperature, light and salinity, and document the crustaceans' every move as they shed their shells, mate and reproduce.


And once the young crabs are strong enough, the scientists pack them on boats and release them in secluded coves near the Chesapeake Bay.

Zohar and Zmora are leading a team of researchers from the University of Maryland Biotechnology Institute and four other institutions around the country in an effort to do what no one thought could be done -- raise crabs in a hatchery, then put them in the bay and watch how they live.


The goal is eventually to increase the population of crabs reproducing in the Chesapeake Bay -- a feat that scientists say has not been accomplished in any body of water anywhere in the world.

Some doubt that it will work. Not only would the hatchery have to produce many millions of crabs to make a difference in the bay, but past attempts to restock the world's waterways with hatchery-raised fish have been expensive disasters.

"If we think of it in the whole big picture of things, we're attempting to do something that history has shown has produced failure after failure," said Donald F. Boesch, president of the University of Maryland Center for Environmental Sciences, a sister institution. He questions whether it is wise to pour so much federal money into the gamble. The project has received $12 million over the past five years at the request of Sen. Barbara A. Mikulski, a Maryland Democrat.

The director of the biotechnology institute's Center for Marine Biotechnology is undaunted. With the future of the blue crab at stake, Zohar said, the biggest failure would be not to try.

"I keep telling people, one reason I came here was because of the crabs," he said. "In light of what's going on in the bay, this is one stone that should not remain unturned. Even if it is not going to work, we're going to learn ... a tremendous amount about the biology of the blue crab."

Since he began the Blue Crab Advanced Research Consortium, Zohar has recruited some of the nation's top experts to answer key questions about the blue crab, Callinectes sapidus, including where it migrates, how fast it grows, and whether it would be a good species for aquaculture. His work is influencing regulations, including a new rule to create a 94-square-mile sanctuary in Virginia for pregnant females.

"They have done things in the lab that nobody thought could be done," said Eric Schwaab, deputy secretary of the Maryland Department of Natural Resources. "They really have learned a lot in a very short period of time that has all kinds of implications for our management efforts."

Even though the blue crab has been a staple of the seafood economy for centuries, biologists and watermen didn't know a lot about it. Unlike the bay's oysters, which have been in trouble for decades, there wasn't much urgency in studying the blue crab. Crabs were not dying of diseases the way the oysters were. And the fishery did not appear to be in trouble -- harvests in Maryland alone are measured in the tens of millions of pounds, according to the Department of Natural Resources, and provide income for more than a thousand watermen.


But several years ago, studies in Virginia and Maryland began to indicate a steady decline in the number of juvenile crabs in the bay. Both states put in fishing restrictions in hopes of reducing harvest pressure and protecting the spawning stocks. Some scientists talked of going a step further -- if they could figure out why the stocks were declining, they might be able to bring them back.

Zohar, a Jerusalem-born, Paris-educated endocrinologist, seemed an unlikely choice to lead the effort. He'd never even seen a blue crab until he was in his 30s, and he'd spent most of his career studying fish. But in 2000, when Zohar was testifying before the Maryland General Assembly about stock enhancement techniques for fin fish, then-Del. C. Richard D'Amato of Annapolis asked him if he could do the same thing to shore up crabs.

Zohar replied that he thought it was possible. D'Amato helped him get $100,000 to try. Phillips Foods, the Baltimore-based seafood company, kicked in $300,000.

Zohar began assembling an all-star team of researchers. He persuaded Zmora, a fish nutrition expert, to leave his post at an Israeli lab in the Red Sea resort of Eilat and move to Baltimore to set up the algae kitchen. Until he walked into the Columbus Center, Zmora had never seen a live blue crab.

Closer to home, Zohar tapped Anson "Tuck" Hines, director of the Smithsonian Environmental Research Center in Edgewater, who has studied the blue crab for 28 years; Romuald Lipcius, a renowned crab biologist at the Virginia Institute of Marine Science; and David Eggleston, who was looking at stock enhancement at North Carolina State University.

"To be honest, I didn't think it could be done," Eggleston said. "I didn't think you could, one, raise crabs in a hatchery, and two, put them in the water and make them stay. ... It's a complicated life cycle. It requires a tremendous amount of attention."


Raising crabs in a hatchery is difficult because they endure nine larval stages in three weeks -- each requiring a precise temperature and food. And crabs are cannibalistic -- the hard ones eat the soft ones, which have shed their shell to grow.

In the bay, the life cycle is even more complex. Crabs burrow into the bay bottom during winter, then begin to mate in May. Pregnant females migrate to salty waters near the bay's mouth to spawn. Their tiny larvae are swept out into the ocean. If the babies can survive for about 60 days, they will be mature enough to return to the bay.

The effort to raise crabs in the hatchery was not entirely unprecedented. The Japanese have been raising the swimming crab for decades. But that species has only four larval stages. And the Japanese have been largely interested in developing a put-and-take fishery, not in doing research.

Hines, who had looked at the work in Japan, thought the hatchery would succeed. But he wondered what the researchers could learn about the crabs once they were put in the water. Wouldn't they swim away?

It turned out that the crabs like the secluded inlets near the Smithsonian's property along the Rhode River, which is surrounded by old-growth forests and summer cottages. Even though the river has hardly any of the bay grasses that crabs favor, the adaptable crustaceans settled in shallow water adjacent to marshes. Many stayed until they migrated to the spawning grounds, giving Hines and his team ample opportunities to study them.

The researchers also placed a few thousand adult crabs in the Rhode, labeled with numbered tags. Watermen who catch these crabs can turn them in for a reward of $5 to $50. About half of the crabs released have come back to the Smithsonian this way, helping to fill in blanks in scientists' understanding of migration patterns.


The research has challenged conventional wisdom. It has shown that crabs grow from larvae to mature adults in about five months, far faster than thought. It also revealed that though crabs mate only once, females hold on to the sperm and can produce multiple batches of eggs.

Boesch acknowledges that the group has learned valuable lessons but fears that Zohar's work is giving false hope to watermen that the species can be restored through a hatchery approach.

"It seems to me that before you make additional massive investments of public funds you have to ask the question, 'Would it actually work?'" Boesch said.

But Maryland Watermen's Association President Larry Simns, who supports Zohar's efforts, says restocking the bay with millions of crabs to support the current fishery was never the goal. The point, he said, was to learn enough about crabs to make good management decisions and to be able to act quickly if the bay population ever nears collapse.

"I felt like there was a lot we didn't know. And most of the time, it's better to know it than not to know it," Simns said. "We needed to be ahead of the curve if we had a crisis."

Hines said the scientists have not proved that they can enhance the stocks, but he hopes they will have the chance to try. "This isn't a quick fix -- that all you have to do is throw crabs in the bay and it will work," he said. "It's one tool in the repertoire of tools that need to be addressed."


Zohar can't help but smile when recalling the early days of his experiment. He's on to the next step -- taking DNA swabs from the crabs so researchers can determine how many make it to the next generation in the bay.

"In science, you need to dare, you need to go out of the box," he said. "I knew, deep in myself, that it was going to work. And it feels good that what we did here may make a real difference in the Chesapeake Bay."