Bioaccumulation of cesium-137 in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned nuclear reactor reservoir

Bioaccumulation of 137Cs was investigated in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned reactor reservoir, Pond B, Savannah River Site, Barnwell Co., South Carolina. The authors collected fish by trap-netting, and determined ages from pectoral spines. Muscle and other tissues were assayed for 137Cs by NaI-scintillation. Music 137Cs was unrelated to sex or mass of fish, but was related to age. Examination of least-squares means suggested that 137Cs in muscle increased up to about age 3, but did not increase with greater age. A modified Richards model showed equilibrium 137Cs concentration in muscle was acquired in approximately 2.4 years. Growth differed between sexes and the time to asymptotic body mass was longer than the time to attain equilibrium 137Cs concentration. Males attained an asymptotic mass of 577 g in approximately 6.3 years; females attained an asymptotic mass of 438 g in approximately 5.9 years. The cumulative 137Cs burden of the population was 4.9 x 106 Bq, representing <0.001% of the 137Cs inventory of the reservoir. Concentration of 137Cs varied among tissues with gill and muscle the lowest and highest. Concentration of 137Cs in ovaries declined with increasing ovary mass. Until equilibrium is attained in these fish, 137Cs concentration is directly related to increasing age rather than size