Baseline studies in the Slave River, NWT, 1990-1994: Part II. Body burden contaminants in whole fish tissue and livers.

The Northwest Territories section of the Slave River is the recipient of chemical compounds from a variety of sources, including upstream industry and agriculture. In 1990, concerned government agencies formulated a practical, focussed, and comprehensive environmental monitoring program to assess contamination in the river and the Slave River Environmental Quality Monitoring Program was established. The program was designed to respond to the distinct requirements of two major monitoring goals. The first priority was to ascertain whether the fish in the Slave River were safe to eat. The second goal was to establish a baseline data set with which to compare future effects from upstream activities and long-range transport of contaminants. From the data gathered in the present study, it appears that whole tissue of fish (muscle) is fit for human consumption. Throughout the monitoring period, consistently low concentrations of organochlorine pesticides, PCBs, dioxin and furan isomers, PAHs, chlorinated phenolics, and heavy metals have been observed and median concentrations have all been below federal fish consumption advisories. Also, the numerous data values below analytical detection limits attest to the relatively uncontaminated nature of the fish. These results were comparable with other studies conducted on arctic animals. The heavy metals observed in fish tissue are probably of natural origins, since inorganic analyses of suspended sediment in the Slave River indicated relatively elevated levels, with no known anthropogenic source. While the present study concluded that contaminant levels in whole fish are low, toxaphene levels in burbot livers should continue to be monitored since concentrations were consistently above fish consumption advisories during the monitoring and are eaten extensively by the native peoples. The second goal of the monitoring program was to develop a baseline data set and the values tabled in the current paper are useful in establishing a foundation for future comparison.