Survival of pink salmon (Oncorhynchus gorbuscha) fry to adulthood following a 10-day exposure to the aromatic hydrocarbon water-soluble fraction of crude oil and release to the Pacific Ocean

Abstract

Saltwater-acclimated, coded-wire tagged, and adipose fin clipped pink salmon (Oncorhynchus gorbuscha) fry were exposed for 10 days to seawater (control) or 25-54 μg·L-1 (low dose) or 178-349 μg·L-1 (high dose) of the water-soluble fraction (WSF) of North Slope crude oil. The WSF was composed primarily of monoaromatics and was acutely lethal to the fry: 96-h LC50 ranged from 1 to 2.8 mg·L-1. After exposure the fry (30 000 per treatment) were released into the Pacific Ocean to complete their life cycle. The experiment was replicated in 1990, 1991, and 1992. There was no consistent significant dose-dependent effect of the 10-day exposure to the crude oil WSF on growth of the pink salmon prior to their release. Adult pink salmon from this experiment were captured in fisheries and also recovered from their natal Quinsam River, British Columbia. Pink salmon from each treatment group were recovered in similar numbers. Exposure of populations of fry to the WSF of crude oil and release to the Pacfic Ocean did not result in a detectable effect on their survival to maturity. Fry from all treatment groups incurred typically high mortality following release, and there were no discernible effects on survival that were attributable to exposure to the WSF of crude oil.