Reproductive health of yellow perch (Perca flavescens) from a biological mercury hotspot in Nova Scotia, Canada

Methylmercury (MeHg) exposure is known to adversely affect the reproductive health of laboratory fish, but its impacts on the sexual development of wild fishes are not well studied. Kejimkujik National Park and National Historic Site (KNPNHS) region of Nova Scotia, Canada, has been identified as a biological mercury (Hg) hotspot. To determine whether Hg was adversely affecting the reproductive health of wild yellow perch (Perca flavescens), sexually mature male and female perch were collected from 12 lakes within KNPNHS (mean muscle total Hg: 0.28-0.54 μg/g ww). Gonadosomatic index and germ cell development of male and female perch were measured, as well as the plasma 17 β-estradiol concentrations of females. These endpoints were compared between lakes, and were related to Hg concentrations measured in perch muscle and liver tissues. Our results indicate that the reproductive health of male and female perch was not adversely impacted by Hg, although a positive relationship existed between the proportions of primary spermatocytes in male testes and muscle total Hg concentrations. Perch were sampled at an early stage of recrudescence, and the tissue Hg concentrations in these perch were generally lower than those in laboratory studies reporting impacts on reproductive health, both of which may explain the absence of effects. Based on the measured endpoints, it appears that reproduction in perch was not affected at Hg concentrations known to affect fish eating wildlife.