Behavioral avoidance as evidence of injury to fishery resources: Applications to natural resource damage assessment

Natural Resource Damage Assessment (NRDA) provisions enacted under Comprehensive Environmental Response Compensation and Liability Act (CERCLA) and the Oil Pollution Act (OPA) empower natural resource trustees to seek compensation for environmental injury resulting from the release of oil or hazardous substances. Under NRDA regulations promulgated under CERCLA, fish avoidance behavior is recognized as an accepted injury, and may be used to support damage claims. In support of an ongoing damage assessment, tests were conducted to determine if avoidance of ambient metals concentrations may contribute to reductions in local salmonid populations. In laboratory tests, rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) avoided mixtures of metals (Cd, Cu, Pb, and Zn) at concentrations that occur in impacted river reaches at a contaminated site (Clark Fork River, MT). Avoidance of metal contamination may contribute to population reductions and preclude restoration of instream populations by prohibiting movement of fish into contaminated areas of the river from uncontaminated tributaries. Laboratory avoidance tests were performed at two testing facilities. The similar avoidance responses observed at the two laboratories demonstrated the reproducibility of avoidance measures.