Some aspects of hepatic function in feral brown trout, Salmo trutta, living in metal contaminated water.

Brown trout, Salmo trutta, exposed to heavy metals (mainly Cd and Zn) for at least 2 years in the Eagle River, Colorado, were examined for liver size and activity of the growth-promoting enzyme, ornithine decarboxylase (ODC) and compared to trout living in an uncontaminated site. Liver-somatic index (LSI) was greater for trout living in the uncontaminated site with the LSI of females being significantly greater than that of males. The LSI for females at the uncontaminated site was greater than that of females at the contaminated site, but males were not different statistically. ODC activity in the livers of both males and females was lower at the contaminated site. However, males and females did not differ with respect to ODC activity. These data suggest that chronic exposure to heavy metals may have important implications for growth and reproduction and possibly survival. The activity of ODC in liver might serve as a useful biomarker when assessing chronic toxicity of metals to naturally reproducing fish populations.