Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Forestry, Wildlife, and Fisheries

First Advisor

Terrence R. Tiersch


A major obstacle in culture of the Malaysian prawn, Macrobrachium rosenbergii, is the complex social structure whereby a few large males dominate the population and reduce production. The goal of this work was to induce reproductive sterility by use of gamma radiation as a means to increase production. Of the 62 publications related to the use of gamma radiation in aquatic species published between 1938 and 1996, 66% did not indicate performance of dosimetry (dosage verification). Samples were not rotated during irradiation in 98% of these studies, which introduces considerable variation in dose. A dosimetric study in this dissertation found a 19% difference in dose rate for a 4-cm difference in height, and a 55% difference for a 4-cm difference in width. Sample rotation reduced variations to 14% vertically and 19% horizontally. Whether the surrounding medium was air or water could cause 218% variation at a particular location. Irradiation of larvae, postlarvae and juveniles showed that survival was inversely correlated with dose of gamma radiation. A dose of 3.0 krad resulted in total mortality within 9 days for larvae, and within 12 days for postlarvae and juveniles. The survival of male and female juvenile prawns exposed to gamma radiation was not different. Irradiation at 0.5 krad during the juvenile stage did not produce sterility. Survival was not significantly different from that of the non-irradiated group. Irradiation at 1.0 or 1.5 krad during the juvenile stage resulted in males with no sperm or reduced numbers of sperm. Females irradiated at 1.0 and 1.5 krad did not produce eggs or produced 35,000 eggs. Males irradiated at 1.0 or 1.5 krad were not able to fertilize the eggs of non-irradiated females. Non-irradiated males were not able to fertilize eggs of females irradiated at 1.0 and 1.5 krad. The achievement of sterile Malaysian prawns by irradiation at the juvenile stage with 1.0 and 1.5 krad of gamma radiation did not result in increased production.