The Pacific eulachon (Thaleichthys pacificus) as a pollution indicator organism in the Fraser River estuary, Vancouver, British Columbia

Eulachons return to the Fraser River each spring and migrate through the estuary to spawn in freshwater. During this migration they may be subjected to varying water quality conditions due to the discharge of domestic and industrial wastes and land drainage. Fish were captured at five estuarine stations in April 1986 and again at three stations in April/May 1988. The locations were from Steveston, at the river mouth, to Port Mann bridge, 31.0 km upstream, just above saltwater influence. Water samples, whole fish, gonads and pooled livers of both sexes were analyzed separately for selected organochlorine contaminants. Water and tissue samples contained chlorophenols from wood preservation operations and chloroguaiacols from pulp bleaching. Whole fish also contained DDE and DDD, while PCBs were present in some fish gonads in 1986, but not in 1988. With the exception of whole body concentrations of 2,3,4,6-tetrachlorophenol (TeCP), concentrations of pentachlorophenol (PCP), 3,4,5-trichloroguaiacol (3,4,5-TCG), tetrachloroguaiacol (TeCG), DDE and DDD in whole bodies, livers and gonads revealed an increasing trend with distance of the eulachon capture site upstream from the Fraser River mouth. Marked differences occurred in the concentration of contaminants in eulachon livers (for example, levels of 50.8 +/- 42.2 ng g-1 3,4,5-TCG at Steveston, and 446.4 +/- 222.5 ng g-1 at Port Mann). The relatively high lipid content of eulachons suggests them to be potential integrators of low-level contaminants in the Fraser River system. This, and their anadromous life history, recommend them as suitable annual monitors of selected organic compounds.