News Release

Harbor Branch Oceanographic Institution's Aquaculture Division Studies Viability Of Controlled Reproduction Of Southern Flounder In Captivity

Peer-Reviewed Publication

Harbor Branch Oceanographic Institution

FT. PIERCE, FL - According to the National Fisheries Institute, annual profits from farmed flounder exceeded $100 million in Japan last year. With the opening of the United States' first flounder hatchery in New England, optimism is high for that kind of success to be achieved in this country. At Harbor Branch Oceanographic Institution, research is underway by the Aquaculture Division to develop commercial viability for the southern flounder, Paralichthys lethostigma. This work is partially funded by the 1997 Disney Wildlife Conservation Fund Marine Awards Program.

Recently, a group of government (state and federal) officials, businessmen and biologists attended the Florida Marine Aquaculture Industry Development Workshop at Harbor Branch. They identified southern flounder as one of the leading candidates for aquaculture development in Florida's marine foodfish industry. The southern flounder is considered one of the top candidate species for commercial aquaculture development in the United States because it tolerates higher temperatures and lower salinities than most other flatfish species and, therefore, can be reared in a wider variety of environments. In addition, flounder species exhibit great potential for aquaculture development due to their excellent market demand and price.

The southern flounder is a left-eyed flatfish found along the U.S. East Coast from North Carolina to Florida. It is also abundant in the Gulf of Mexico from northern Mexico to Florida's west coast, but it is absent from southern Florida. Adults are found in coastal estuarine waters throughout the year, but undergo annual spawning migrations to offshore waters in late fall to early winter. Large individuals reach 60-91cm (23-26 inches), however, the largest unofficially captured southern flounder weighed 25 pounds! Fish caught in central Florida greater than 2lbs, 17 inches tend to be females. It has been suggested by researchers at the Texas Parks and Wildlife Department that females are faster growing, longer lived and reach a larger size than males. At Harbor Branch, we are also investigating whether individuals may be hemaphroditic, changing sex as they attain a larger size. This hypothesis that we have developed is based on data collected from wild caught fish.

Wild broodstock flounder were captured between November 1997 and January 1998 during their annual migration from their feeding grounds in the Indian River Lagoon to their offshore spawning grounds. The broodstock were photothermally acclimated in circular tanks in a maturation room at Harbor Branch. Salinity was raised to replicate the oceanic environment and to facilitate floatation and tank collection of fertile eggs. Four females and one male were implanted with hormonal pellets and began tank spawning 12 days post implantation and continued to yield fertile spawns for a period of 14 days. Fertile eggs were recovered from a tank egg collector over this period. The best six spawns were transferred to larval rearing tanks to commence an experimental larval rearing trial.

Although difficulties were encountered during the weaning phase of the project, Harbor Branch researchers are encouraged by broodstock spawning success and high larval survival rates through metamorphosis. Research will continue this fall on the controlled reproduction of southern flounder in captivity. Research efforts will focus on increasing the fecundity yield of the broodstock and increasing the survival rate of fry during weaning. Grow out trials in Harbor Branch's recirculating saltwater systems and in offshore cages managed by SeaFish Mariculture are planned for 1999.

There will be an "Advanced Techniques in Marine Finfish Aquaculture" Course offered at Harbor Branch this summer featuring flounder and snapper. The 14-day course includes the practical aspects of marine fish aquaculture from broodstock acquisition through growout methods. In addition, classroom lecture topics will cover fundamentals of nutrition, bioenergetics and disease control. The class will be taught by Dr. Daniel Benetti, July 13-26, with a tuition cost of $1,995. For additional information or to register for this course, please contact the ACTED program at Harbor Branch Oceanographic Institution at (561) 465-2400, extension 416.

Harbor Branch Oceanographic Institution, Inc. is one of the nation's premier not-for-profit oceanographic research and education facilities, dedicated to the exploration of the world's oceans, estuaries and coastal regions, for the benefit of all humankind.

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