The BLM has been studying the concentrations of metals in fish and aquatic insects along the Kuskokwim River and several tributaries upstream and downstream of the Red Devil Mine since 2010. The study covered non-salmon species since they are resident within the river (non-anadromous) and make up a large portion of the diet of subsistence users in the area.
During June-July 2010 and September-October 2010 phases of the study, the Alaska Department of Fish and Game collected fish tissue samples for the BLM from adult northern pike, sheefish, burbot (or lush), Dolly Varden, and arctic grayling in the lower stretches of the George and Holitna rivers, in addition to 73 miles of the Kuskokwim River from Stony River to Crooked Creek.
During this portion of the project, BLM fisheries staff also collected aquatic insects and juvenile fish, including Dolly Varden, arctic grayling, long-nosed sucker, and slimy sculpin, from eight small streams that flow into the Kuskokwim River. The farthest downstream tributary sampled as part of this study was an unnamed stream just below the George River. The most upstream tributary sampled was Vreeland Creek, which enters the Kuskokwim River just below Sleetmute.
U.S. Geological Survey water resources staff helped the BLM with the study by collecting water and sediment samples from each tributary. They also collected water and sediment samples from the Kuskokwim River upstream of Sleetmute where the Kuskokwim joins the Holitna River and also at Crooked Creek. The BLM is in the process of evaluating these samples in conjunction with the analysis of the fish tissue and aquatic insects to get a clearer understanding of concentrations in the aquatic ecosystem of the middle Kuskokwim River.
The BLM, in coordination with local communities, funded the collection of additional burbot samples from the Kuskokwim River after freeze-up to increase the sample size for this species. The Alaska Department of Fish and Game collected these additional samples and submitted them to the laboratory for processing in late February 2011. The results of the 2010-11 sampling were summarized in an interim report in 2012 (below).
The BLM received funding for a fish tracking project to determine the seasonal movements of northern pike, burbot, and Arctic grayling in the middle Kuskokwim River in 2011. From 2011-2012, the Alaska Department of Fish and Game surgically implanted 150-200 transmitters in pike and also burbot. The tagged fish would also be tissue sampled for contaminants analysis using non-lethal biopsy samples. Additionally, Arctic grayling were sampled for contaminants analysis, with 100-150 indivisuals surgically implanted with transmitters for examining seasonal movement patterns.
The seasonal movements of pike, burbot, and grayling were documented using ground based tracking stations as well as fixed wing flights led by the Alaska Department of Fish and Game for several years. The concentrations of contaminants found in fish tissue, seasonal movements of pike, burbot, and grayling, and the known locations of mineral deposits in the region are the focus of analysis currently being completed by agency staff. The interim report released in 2012 (below) will be integrated in a final study report which is expected for release in January 2017.