Caudal fin mercury as a non-lethal predictor of fish-muscle mercury

The caudal (tail) fins from 17 walleye (Sander vitreus) and 12 northern pike (Esox lucius) from three northern Arizona lakes (Long Lake, Soldier Lake, and Upper Lake Mary) were analyzed for total-Hg by combustion-atomic absorption spectrometry. Results indicate that the fin contains measurable Hg that correlates with muscle-Hg concentrations. As the body burden of Hg increased, the concentration in the fin increased relative to the muscle. Mercury concentrations also increased with fish length and weight, although the relationship was lake- and species-dependent. Fish from Soldier Lake had the most efficient uptake of Hg, likely due to the trophic structure of the lake or the condition of the fish, but possibly due to an acute source of Hg. Overall, this study demonstrates that caudal fin clippings can be used as a non-lethal predictor of muscle-Hg concentrations, which can reduce the number offish killed in routine monitoring programs.