Oil pollution in the Argentine Sea (South Atlantic) has been damaging sea birds. Necropsies were made on 25 individuals (both oil-covered and not) captured in seven different places of Chubut province. The histopathological studies were performed using ordinary techniques.

Tar granules, phagocytized by the macrophages were found in oil-covered individuals, as well as in those which, macroscopically, seemed free of oil. These were found in different organs, with the highest concentration in the salt gland and the lungs.

Those lesions concomitant with the presence of tar granules are analyzed as well as the connection between external state and the lesions in internal organs.

In the second phase of this study, we determined the safety of using the biopsy technique. Two hundred 150-200 mm clinically healthy rainbow trout were assigned randomly to one of four groups. Each fish in group I was biopsied as described previously. During biopsy, fish were restrained to prevent movement by firmly clasping the head with one hand and the body with another hand. Biopsy was then performed by a second individual. Fish in group 2 were sedated in groups of five until nearly unconscious with tricaine methanesulfonate (Sigma Chemical Company, St. Louis, MO) and were then biopsied. Fish in group 3 were sedated, but not biopsied, and fish in group 4 were handled as in group 1, but not biopsied, Fish were placed into raceways and observed daily for morbidity and mortality for I week.

No significant differences were found between the 4 groups. The only mortality occurred in the sedated fish in group 2, where four of fifty fish died. All mortalities occurred within the first 24 hours of biopsy. Fish which died developed areas of dark pigmentation on the skin prior to death, suggesting possible neurological damage to the spinal cord or to adjacent nerve roots.

These results suggest that kidney biopsy in live fish is feasible and that bacterial diagnoses obtained in this manner are statistically equivalent to those from necropsy.

References

1.  Bullock, A.M., 1978. Laboratory methods. In: R.J. Roberts (editor), Fish Pathology. Bailliere-Tindall, London, pp. 235-267.

2.  Galen, R.S. and Gambino, S.R., 1975. Beyond normality: The predictive value and efficiency of medical diagnoses. John Wiley and Sons, New York, New York, 237 pp.

3.  McDaniel, D. (Editor), 1975. Procedures for the detection and identification of certain fish pathogens. American Fisheries Society, Bethesda, Maryland, 118 pp.

4.  Wolf, K., Quimby, M.C., Carlson, D.P., and Bullock, G.L., 1968. Infectious pancreatic necrosis: Selection of virus-free stock from a population of carrier trout, J. Fish. Res. Bd. Can., 25:383-391.

5.  Yu, K.K., MacDonald, R.D. and Moore, A.R., 1982. Replication of Infectious Pancreatic Necrosis Virus in trout leucocytes and detection of the carrier state. J. Fish Dis., 5:401-410.