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National news release

about research by Mitchell and Griffin (Sept. 2002)
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BELTSVILLE, Md., Feb. 12—Developing a pond shoreline treatment to control aquatic snails that spread disease to farm-raised catfish has won researchers Andrew J. Mitchell and Billy R. Griffin an award for technology transfer from the Agricultural Research Service.

ARS, the U.S. Department of Agriculture's s chief scientific research agency, will honor Mitchell, Griffin and other scientists today at a 1 p.m. ceremony at the agency's Henry A. Wallace Beltsville Agricultural Research Center.

Mitchell and Griffin developed their shoreline treatment at the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center in Stuttgart, Ark. Griffin recently retired from the center.

The researchers developed a method to stop a flatworm, known as Bolbophorus confusus, that can lead to serious economic losses for catfish producers. Eggs from the flatworm are shed from the American white pelican's intestinal tract into channel catfish ponds, where they hatch and form larvae that infect an intermediate host, the ram's-horn snail, or Planorbella trivolvis. Once the larvae multiply and mature inside the snail, they exit and find fish to infect. The cycle begins again when a pelican eats an infected fish and the flatworm reaches maturity inside the bird.

Cases of the disease were first seen in the Mississippi Delta in 1999. Fish infected with B. confusus develop small cysts in their flesh, often seen as bumps just below the skin. The disease can kill smaller fish, and it lessens the appetites of larger fish that survive. This retards the growth of the fish, making them unsuitable for market and susceptible to other diseases. Currently, there is no cure for infected fish.

Mitchell and Griffin developed technology targeting the ram's-horn snail. They produced a solution of copper sulfate and citric acid to apply to the shoreline of fish ponds using a specially designed nozzle. The snails are killed, but fish are repelled by the treatment and avoid the shoreline. The treatment disperses throughout the untreated pond water and becomes diluted to concentrations that are not toxic to fish.

The treatment has proven very effective at reducing the threat of the parasite to farm-raised channel catfish. The parasite has been found in catfish in Mississippi, Louisiana, Arkansas, and most recently California. The treatment is currently being used in Mississippi and Arkansas.

"The researchers have worked tirelessly to present their findings at several workshops and annual meetings to get the word out and into the hands of producers and suppliers," said Edward B. Knipling, acting administrator for ARS.

The researchers began work on the project in 1999, and the treatment was adopted by the fish industry in 2000 after approval by the U.S. Environmental Protection Agency. As a result, Arkansas has not had a serious snail infestation since the state began widely using it.

The scientists teamed up with private industry to develop data to support the EPA application for registration. They are working with Phelps Dodge Refining, Inc., of El Paso, Texas, to transfer the technology to new areas, including control of a serious protozoan parasite of fish. They also wrote articles for publication in newspapers, extension publications, trade journals and scientific journals, including the North American Journal of Aquaculture.

Mitchell has a B.S. in biology from Glassboro (N.J.) State College and an M.S. in fisheries from Auburn University. He lives in North Little Rock, Ark., with his wife, Sandy. They have three children and two grandchildren.

Griffin is a native of Prescott, Ark., where he resides with his wife, Marsha. They have four children and seven grandchildren. Griffin received a B.S. in biology from Arkansas Polytechnic College and an M.S. and a Ph.D. in microbiology from the University of Arkansas.