Mercury in catfish and bass from the snake river in Idaho.

Abstract

Monitoring was undertaken to determine differences between fish taken in impoundment areas and, at the same time, determine whether mercury levels increased with age of the fish. Results of the study corroborate the findings of other investigators in the case of bass alone; not so with the catfish studied. With the bass, for example, there was an increase in mercury concentration from 0.59 ppm to 0.72 ppm between the ages of two and four years in the impounded waters and from 0.67 ppm to 1.15 ppm for the same age period in the free flowing waters. Also there was a small increase in the mean values of from 0.65 to 0.79 ppm between the former to the latter group. This condition was not apparent, however, in the case of catfish, where both patterns with respect to age and habitat, if anything, seemed to be reversed. In all cases, however, except for catfish in the free flowing waters, the mean levels for mercury concentration set by the F.D.A. (0.50 ppm) was exceeded. On this basis, these results would seem to be of some concern to anglers.