They represent species of the small fish and any other prey of proper size. In the remainder of this report, common names rather fifth trophic level. than scientific names will be used for convenience. SAMPLE PROCESSING AND ANALYSIS Sample processing and analysis began with counting and partially thawing the fish from each location. was recorded. The total weight, length, and sex of each fish tissue, into muscle Each fish was dissected bone (cranial, thoracic, vertebrae, ribs, pelvic and pectoral girdle), skin and scales (fins discarded), stomach (gizzard) contents, liver, and remaining viscera that + eins PenneeEY Toate diigo og Ceaa eee generally included large and small intestines with contents, stomach wall, spleen, kidney, and mesenteries. The concentrations determined in the viscera samples are regrettably less descriptive than those for other tissues because of the matrix of organs and tissues represented. In some instances, however, a finer division of the visceral components was made. organ of the species from the same catch was pooled. Each separate tissue and It was necessary to pool tissues from a particular catch for analysis because of the low concentrations of transuranic radionuclides anticipated in edible muscle tissue. This resulted in the mixing of fish from several populations (weight classes) and of different sexes. Because mixing masked any differences in concentration related to weight (size), sorting of different size classes for processing was accomplished, in some instances, to assess the relationship of radionuclide concentration with weight. We were unable to relate any differences in concentrations of specific radionuclides with sex. the fish but not analyzed. Gills were separated from Our experience at Bikini and Enewetak Atolls showed that gills were frequently contaminated with sediment. Gills are not eaten and questionable information would be gained from their analysis because of the possible contamination. After the wet weight was determined, each pooled fish tissue sample was dried in ovens at 90°C to constant dry weight and ashed in muffle furnaces at 450°C. The only samples analyzed for ¢!0po9, not prepared in this way were the samples to be In those cases, wet tissues and organs were used. . The scientific objectives for the analysis of fish in the Marshall Island Program changed over the years. For example, initially fish were collected to assess the concentration of radionuclides in tissues of different species. of 5000561 | 7 |