ACCUMULATION AND RETENTION OF CESIUM'" BY MARINE FISHES 



BY John P. Baptist and Thomas J. Price, Fwhery Research Biologists 

 Bureau of Commercial Fisheries 



The problem of fishes being polluted by radio- 

 active materials released into the aquatic en- 

 vironment ' becomes increasingly important with 

 the continued development of atomic energy. 

 A major source of pollution has been the detona- 

 tion of nuclear weapons which released large 

 quantities of radionuclides into the environment 

 (Revelle and Schaefer, 1957). These have made 

 a negligible contribution to the total radioactivity 

 of the sea, but have temporarily contaminated the 

 test areas (Kawabata, 1955; Donaldson and 

 others, 1956; Seymour and others, 1957). There 

 is also a possibility that the oceans may be used 

 for the disposal of concentrated radioactive wastes 

 from the increasing number of atomic reactors 

 (Revelle and Schaefer, 1957). This possibility, 

 along with the testing of nuclear weapons and the 

 present dumping of low-level wastes, emphasizes 

 the need for evaluation of hazards to man through 

 fisheries. Such an evaluation can be made only 

 with a knowledge of the disposition of these 

 radionuclides in the biology of marine organisms. 



Radioactive Cs is readily accumulated in the 

 tissues of animals and is therefore a hazard to 

 man when it is released into a marine environment 

 containing animals used as food. Krumholz 

 (1956) found that about 75 percent of the radio- 

 activity in soft tissues of bluegills and crappies 

 in a contaminated lake resulted from Cs"'. 

 Suckers in the Columbia River accumulated 

 substantial amounts of this radionuclide in muscle 

 (Davis and others, 1958). Small amounts of 

 Cs'" were found in fish muscle, marine algae and 

 fish-eating birds during a resurvey of two atolls of 

 the Marshall Islands approximately 1 year after 

 "Operation C^astle" (University of Washington, 

 1955). Pendleton and Hanson (1958) followed 

 the accunmlation of Cs'" through food chains in 

 aquatic environments. They reported that car- 



' Thi.s investipation was conducted as part of a research program sponsored 

 jointly by the U.S. Bureau of Commercial Fisheries and the U.S. Atomic 

 Energy Commission. 



Approved for publication July 21, 19fil. Fishery Bulletin 206. 



nivorous vertebrates had higher concentration 

 factors than omnivorcs. Working with inverte- 

 brates, one of the authors, T. J. Price (unpublished 

 data), found that clams and oysters concentrated 

 Cs'" si.x times over that by sea water in 20 days, 

 whereas muscle of scallops had a concentration 

 factor of 10 in 10 days. 



The metabolism of radioactive Cs by domestic 

 and laboratory animals has been studied by vari- 

 ous workers. Weeks and Oakley (1955) fed rats 

 regularly with Cs'" as an inorganic solution, 

 biologically incorporated in plant material, and 

 mixed with plant material. Their results in- 

 dicated that absorption was not affected by the 

 form in which it was fed and that the greatest 

 accumulation occurred in muscle. While study- 

 ing the metabolism of Cs'" in rats, cattle, sheep, 

 swine, and chickens. Hood and Comar (1953) 

 found a high degree of absorption of ingested 

 Cs'", long-term retention and similar concentra- 

 tion patterns among species and among tissues. 

 Ballon and Thompson (1958) administered Cs'" 

 to rats both in single doses and over a long period. 

 They found that predictions of the long-continued 

 buildup, based on single dose data, were in close 

 agreement with the results from the prolonged 

 feeding experiment. 



The present experiments were undertaken to 

 follow the accumulation of Cs'" by fish, both 

 from sea water and from ingested doses; and to 

 determine its biological half-life (t^), which is 

 the time required for an organism or tissue to 

 lose one-half of a given substance by biological 

 elimination. 



METHODS AND MATERIALS 



Fish were collected in the vicinity of Beaufort, 

 N.C., and included the following species: post- 

 larval summer flounder, Paralichthys dentatus 

 (Linnaeus), weighing 17.6-48.6 milligrams; At- 

 lantic croaker, Micropogon undvlatus (Linnaeus), 



177 



