-4e fish as for man. In addition, the radiation dose to fish in the sea would be less than the dose to man on land because of the greater dilution of the radioactive contaminants by the mixing processes of the sea. For information on the lethal effect of radioisotopes in the sea upon fish, reference is made to observa- tions at the Bikini-Eniwetok test site where the United States has tested its largest nuclear devices. The levels of radioactivity are considerably greater in the BikiniEniwetok area than elsewhere in the oceans, and therefore the effects would be expected to be more evident. Dead fish have been observed in the vicinity of the detonation of nuclear devices at Bikini-Eniwetok, and although the cause of death was not known for sure, it is reasonable to believe the cause was more likely to have been from blast effects or radiation released at the instant of the detonation than from the radioisotopes in water. In the absence of the effects of blast,and heat, death to fish from ionizing radiations could ,be expected in the immediate vicinity of the detonation of a large device. However, death resulted solely from radioactivity in the water, mortalities would be expected to occur over an extended period of time and area, but this condition has not been if