Ardjosoediro, I., N. Lee, J. E. Supan, and T. R. Tiersch, Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70820

The oyster industry in Louisiana with an annual farm value of ~50 million dollars, represents an important economic and sociological component of coastal communities. Annual oyster production in Louisiana provides about two-thirds of the oyster production in the Gulf Region. The eastern oyster industry, however, is currently subjected to several problems including environmental pollution, saltwater intrusion with resulting marsh loss, oyster predation, increased harvesting pressure, and diseases. In addition, profits are lost during the spawning season due to poor meat yields. Commercial application of radiation has been proven in chemical, civil, electrical, and mechanical engineering. The use of radiation in agriculture started around 1940 when gamma radiation was applied to control livestock insect pests by inducing reproductive sterility. The possibility of producing sterile oysters through irradiation represents a potential benefit for the oyster industry.  Improved meat yields during spawning season could increase profits. Furthermore, hatchery production of seedstock could more readily take advantage of genetically modified oysters if irradiation prevented unwanted provided control of reproduction. The effects of gamma radiation on the spat of Crassostrea virginina were evaluated during this study. Spat were produced using standard procedures at the oyster hatchery at Grand Isle, Louisiana. The spat were 11.5 + 2.3 mm in length (mean + SD) and 9.5 + 1.9 mm wide. They were exposed to gamma radiation doses of 0, 10, 20, 30, or 40 krad at a rate of 1546 rad/min. The study lasted 8 months from September 1998, through April 1999. In a preliminary trial, gonadal development was evaluated histologically in April of 1999. Gametic stage and sex (male, female, hermaphrodite, or unidentifiable) were determined for each oyster. During this study all spat died when exposed to 20 krad and above. The remaining oysters (0 and 10 krad) were evaluated for gonadal development. The gametic development of the non-irradiated oysters was higher (mean gametic stage = 2) than that of the oysters exposed to 10 krad (gametic stage = 1.3) (Table 1). The occurrence of hermaphrodites was higher among the irradiated oysters (4 of 15; 27 %) than among the non-irradiated oysters (1 of 13; 8%).

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Texas Chapter of the American Fisheries Society
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