May 2002 Update on Hatchery Research
 

Maryland’s beautiful swimmers are now finding themselves in condos at Baltimore’s Inner Harbor. The University of Maryland  Biotechnology Institute’s (UMBI) Center of Marine Biology (COMB), Phillips Foods and Seafood Restaurants (Phillips) and the Maryland Watermen’s Association are working together to learn more about the lifecycle of our Chesapeake blue crab, also known as Callinectes sapidus, or “beautiful swimmer.”

 The Program:

           The crab research program, called “Crab Restoration and the Bay” or C.R.A.B., unites both the financial and mental resources of several groups, including Phillips, the Maryland Watermen’s Association, UMBI’s COMB, the Smithsonian Environmental Research Center (SERC), and the State of Maryland, among others. Seed money from the State of Maryland helped COMB initiate the Blue Crab Research Program in the Fall of 2000. Maryland’s Dept. of Business and Economic Development has funded an additional $300,000

          Stephen Phillips, CEO of Phillips and a third-generation waterman, has contributed $300,000 toward the hatchery and will continue support through a fund-raising program at his seven restaurants. Phillips’ own crab scientist, Dr. Clive Keenan, will be part of the multidisciplinary team conducting the research. Leading that research effort is Dr. Yonathan Zohar, assisted by Dr. Moti Harel, both scientists with COMB. Dr. Anson Hines of SERC will also work with the researchers, and scientists along the Eastern seaboard have also contacted COMB to possibly collaborate on this project.

          The Maryland Watermen’s Association will help manage incoming grant money through its newly-created non-profit corporation and solicit available funding as the project continues. Additionally, the knowledge of watermen will be incorporated to help frame research questions and guide continued developments in the program. Jennie Hunter-Cevera, UMBI President, said she is glad to be working with the Watermen’s Association because she recognizes their researchers “need the wealth of indigenous information that the watermen have.”

 The Results:

           Fertilized females were gathered in the Winter from areas throughout the Bay, then placed in recirculating closed-loop tank systems at the COMB hatchery, located in Baltimore’s Columbus Center on Pratt Street. Researchers manipulated photo and environmental conditions to encourage spawning. In January, the first female spawned, followed by a second spawning in March and a third upcoming in early May. Contrary to current scientific opinion, researchers have discovered that females can spawn two and even three times - something watermen have been saying for years. The female also can release her eggs either all at once or in several batches, another new revelation. Each female can carry over 1 million eggs in her “sponge” or egg sack.

          Once hatched, the tiny larvae are placed in a tank and fed diatoms and zooplankton for several weeks until they molt eight times, maturing to the next life phase, called “megalopa.” In the first hatch, approximately 30,000 larvae started out in the tank, and approximately 25% of these made it to the megalopa stage. At this point, the small crabs are cannibalistic and must be moved into tanks with shelter for the maturing juveniles. COMB researchers are experimenting with different habitat environments to see which provides optimum protection for the hungry and predatory crabs.

          The megalopae become small juvenile crabs, and when they reach about 1/2 inch in length, they are moved to individual “condos,” or stapled rings in stacks of trays with continuously flowing water and nutrients. In the January spawning, released eggs matured to 35 mm juveniles in only 60 days, a growth rate much faster than what has been reported for blue crabs in the wild.

          About 5000 juvenile crabs from the January spawning are currently in the condo phase at the COMB hatchery. Project Manager, Dr. Moti Harel, explains that their small circular homes protect them, since “given the best food available, they will still eat each other.” The blue crab’s consistent desire to consume its brethren remains the primary challenge facing large-scale hatchery production. Separating millions of juveniles, then successfully providing food and flowing water to them will necessitate creative and cost-effective ideas as production expands.

Why do all this work?

          Faced with a steady and steep decline in the blue crab population, Maryland, Virginia and the Potomac River Fisheries Commission have all cut back on fishing effort to protect the existing population of spawning crabs. Without better knowledge of the crab’s lifecycle and habitat needs, fishery managers are handicapped in their decisions. Researchers hope this hatchery effort will answer questions about the blue crab’s environment, physiology and molecular structure that will enable managers to make better choices about how we can promote and protect a sustainable fishery.

          Researchers at COMB are basing some of their efforts on similar work done in the Japanese Seto Inland Sea. Their native crab, Portunus trituberculatus or swimming crab, is a relative to our blue crab. Their fishery crashed in the 1960’s, and COMB researchers attribute the stock’s comeback to an intensive hatchery and restoration program in which 55 million juveniles were raised and released annually.

          Ultimately, all the partners in this project seek the creation of a statewide, multidisciplinary study to sustain and enhance the Chesapeake blue crab. Such a program could include a network of hatcheries, along with standardized monitoring and habitat restoration.