Determining exposure history of northern pike and walleye to tailings effluence using trace metal uptake in otoliths

Determining the effects of mining activity on fish populations is complicated by the uncertainty of fish residency in an affected area. Otoliths are considered to be metabolically inert and can contain complete chemical records of environments in which individuals have lived. When coupled with the annular structure, otoliths provide temporal information to the history of exposure to pollutants. In this preliminary study, northern pike and walleye otoliths collected from two lakes adjacent to base metal mine tailings at Lynn Lake, Manitoba, Canada, were analyzed using laser ablation inductively coupled plasma mass spectrometry to determine background levels of trace metals. The presence of overlapping Zn, Cu, and Pb peaks above background levels in some otoliths is interpreted as a record of elevated levels in the environment. These otoliths provided a record of the history of fish movement into and out of the affected area.