Total mercury concentrations in anadromous Northern Dolly Varden from the northwestern Canadian Arctic: A historical baseline study

- THg were measured in Dolly Varden from the Yukon and Northwest Territories.
- Length-adjusted THg concentrations were not related to latitude or longitude.
- Among-population variation in THg was best explained by fork-length.
- Length-adjusted THg concentrations were related to age, δ15N, and δ13C.
- Mean THg were below Health Canada's consumption guideline for commercial fish.

Previous research has documented the significance of total mercury (THg) as a northern contaminant in general and of fish in particular. While much research has been devoted to documenting both spatial and temporal changes in THg in consumed fish, little effort has been directed at understanding patterns of THg in Dolly Varden (Salvelinus malma), a prized subsistence species throughout the western North American Arctic. Here we report historical THg concentrations for anadromous Dolly Varden from 10 populations in the Yukon and Northwest Territories sampled across a range of latitudes (67-69°N) and longitudes (136-141°W) between the years 1988-91. Unadjusted mean THg concentrations ranged from 15 to 254 ng/g wet weight. Length-adjusted THg concentrations were significantly different among sites, but were not related to latitude or longitude. Within and among populations, THg was significantly related to fork-length, age, δ15N, and δ13C, with the variation in THg found among populations being best explained by size. The data serve as an important baseline against which future changes in THg levels in this important subsistence fishery may be compared to determine the significance of any observed trends.