Spatial Heterogeneity of Mercury Bioaccumulation by Walleye in Franklin D. Roosevelt Lake and the Upper Columbia River, Washington

Abstract

We examined mercury concentration muscle walleye Stizostedion vitreutn from three reaches in Franklin D. Roosevelt Lake, a reservoir on the Columbia River, and from the upper Columbia River, area contaminated wastes from metal mining associated processing activities. objectives were describe relation between size walleyes tissue concentrations mercury compare mercury concentrations within single reservoir system among spatially segregated cohorts. Overall, mercury concentrations walleye muscle ranged from 0.11 0.44 mg/kg (wet weight) were positively correlated with-age, weight, length fish. Mercury concentrations walleyes varied spatially within system; highest concentrations were fish from lower middle reaches the reservoir. Condition factor age-2+ fish inversely related to tissue concentration mercury lower fish from the lower and middle reaches than in fish from the upper reach. Spatial patterns in condition factor and mercury in walleyes were unrelated to concentrations of total mercury in surficial bed sediments, which ranged from less than 0.05 to 2.8 mg/kg (dry weight). We suggest that the observed spatial differences in the concentrations of mercury in walleyes may be attributed to the fish preferring to spawn forage specific areas where bioavailability mercury varies to local differences in the physical and chemical environment.