Using on-site bioassays to determine selenium risk to propagated endangered fishes

The Utah Reclamation, Mitigation and Conservation Commission is determining the feasibility of establishing a hatchery and grow-out facility for endangered June suckers Chasmistes liorus at Goshen Warm Springs, Utah. A survey of water quality indicated that selenium and other contaminants may be of concern at Goshen Warm Springs. We conducted an ecotoxicological study with three objectives: (1) to determine the growth rates of juvenile June suckers in two ponds (Lily Pond and North Pond) at Goshen Warm Springs and in Utah Lake, (2) to determine the uptake and depuration rates of selenium in juvenile June suckers, and (3) to evaluate limnological factors that may influence growth and selenium accumulation in June suckers. Fish growth was significantly greater at Utah Lake and North Pond than at Lily Pond or under current hatchery conditions. At the end of the uptake phase of the study (day 87), selenium concentrations in June suckers from Lily Pond, North Pond, and Utah Lake were 1.62, 1.90, and 1.32 μg/g of dry weight, respectively. Selenium uptake in June suckers was statistically significant at Lily Pond (0.005 μg·g⁻¹ ·d⁻¹), North Pond (0.010 μg·g⁻¹ ·d⁻¹), and Utah Lake (0.003 μg·g⁻¹ ·d⁻¹). At day 87, the fish were transferred to well water for selenium depuration. Significant selenium depuration occurred after the transfer of June suckers to clean water. Results indicated that selenium bioaccumulated to statistically significant levels at both Lily and North ponds. However, these concentrations are not likely to be of concern because they are not known to cause chronic toxicity. Depuration experiments indicated that June suckers stocked into Utah Lake would eliminate accumulated selenium residues within 3 months. Results indicated that Goshen Warm Springs could be used for fish propagation. In addition, further evaluation of Utah Lake as an interim hatchery site for June suckers should be considered.