Mercury concentrations in fish from the Great Smoky Mountains National Park

Excessive mercury concentrations ostensibly due to pollution have been widely reported in fish tissue. The concentrations of mercury occurring naturally in fish tissue have not been well defined. A collection for mercury analysis of 198 fish of five species was made in 1972 in three high altitude streams in the Great Smoky Mountains, 20–25 km from the nearest pollution source. Mercury concentrations were (means, p.p.m.): rainbow trout Salmo gairdneri, 0.036; brook trout Salvelinus fontinalis, 0.018 ; banded sculpin Cottus carolinae, 0.025; rosyside aceClinostomus funduloides, 0.044; stoneroller Campostoma anomalum, 0.039. There was no significant difference in mercury concentration among fish analyzed whole, with gastrointestinal tract removed, or a strip of axial musculature. There was a significant (P0.05) difference in mercury concentration among species in one stream and in three species from different streams. A second collection of fish of the same species in 1973 verified the 1972 results. Methylmercury constituted 93 ±2.6% of total mercury. These results indicate that all fish acquire about the same tissue concentrations of mercury at chronic exposure to very low levels.