Otolith microchemistry applied to environmental effects monitoring in the Keno Hill mining district

The overall goal of this project was to assess, in three stages, the use of fish otolith microchemistry as a potentially new monitoring tool to be applied around Yukon mine sites. High quality environmental assessments are critical to sound land and water use management as part of all mining development. Improvement of the environmental assessment and prediction of potential impact of land use activities rely on the development of scientific tools and techniques. Fish otolith chemistry integrates information on contaminant exposure and life history of both individual fish and populations. This technique affords a unique opportunity: otoliths consist of a calcium carbonate structure in the inner ear of fish deposited in daily to annual increments. They have been used to determine age and life history events of fish and fish populations. As otoliths are metabolically stable, the contaminant levels within their annular structure can provide a temporal record of exposure of the fish to trace metals and can be used to get baseline data information required for environmental assessments and reconstruct historical exposure for the further protection of aquatic wildlife. As new mining projects are developing in the Yukon, it is believed that Yukon would benefit in establishing a fish otolith chemistry technique and database with the local population, which in turn gave rise to this project.