-13Evaluation of Radioactivity in the Biological Samples Fish As part of the program to evaluate the residual radioactivity in the food items of the Marshall Islands, reef fish and some lagoon fish were collected from several areas in Rongelap and Ailinginae Atolls (Tables 3 and 4). The fish were collected by underwater det onations using Prima- cord or by poisoning with derris root. Some specimens were caught in the deeper waters of the lagoon with hook and line. The species selected for analysis were those commonly found in the Marshall Islands and included damselfish, groupers, parrot fish, squirrelfish, surgeonfish, goatfish, wrasse, snappers, mullet and tuna. The scien- tific names of the species are given in the appendix of UWFL-42. The tissues used for analysis of radioactivity were skin, muscle, bone, liver and other viscera. The latter included part of the stomach contents as well as part of the alimentary canal, in most cases. From the October 1255 collections only the muscle, bone and liver were used, as these three tissues represent, in the above order, the minimum, intermediate and maximum amounts of radioactivity found in the tissues and serve as the best examples of the trends. The itemized data for the October 1955 col- lections of tissues and specimens of fish are listed in Appendix B. The collections from Kabelle Island, which were taken over a longer period than those from the other islands, offer the best data for determination of the decline of radioactivity in the fish. The collections from this