Cutthroat trout (Salmo clarki) were exposed for 90 days in the laboratory to a refined oil collected from the North Platte River at a seepage site below the American Oil Company refinery at Casper, Wyoming. Fish were exposed to five concentrations and a control, and seven biological responses (survival, growth, gill pathology, liver pathology, caudal fin erosion, caudal fin pathology and swimming performance) were correlated with water concentration and tissue accumulation of petroleum hydrocarbons. Fish in the highest water concentration, 183μg/L total oil, accumulated tissue concentrations of 4.6μg/g total naphthalenes and responded adversely to all seven biological measurements. Cutthroat trout in the lowest water concentration, 24μg/L total oil, had a mean tissue concentration of 1.2μg/g total naphthalenes, but their response was similar to that of the control fish to all seven biological responses. Fish exposed to 39μg/L water concentration accumulated tissue concentrations of 2.7μg/g and responded negatively to 2 of the 7 biological measurements. Therefore, the maximum safe limit for this oil and cutthroat trout is between 24 and 39μg/L.
