| Summary: | Mercury (Hg) is a ubiquitous contaminant with harmful impacts on the aquatic ecosystem as well as human health. Studies to date of the bioaccumulative effects of Hg on northern fishes have focussed on all but one of the key species consumed by humans. The exception is the Northern Dolly Varden (Salvelinus malma malma), prized as a food resource in the western Canadian Arctic. Northern Dolly Varden contaminant data were twinned with δ13C and δ15N stable isotope signature data as a means of relating observed variations in total mercury (THg) to feeding strategies. The objective of this thesis was to use archival tissue samples obtained from populations separated by space, time and life-history type to examine the spatial, temporal and life-history trends in Northern Dolly Varden THg concentrations as well as build a historical baseline against which future changes in contaminant loading may be assessed. Historical THg spatial trends for anadromous Northern Dolly Varden were determined 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 1988-1991. Unadjusted mean THg concentrations ranged from 15 to 254 ng/g wet weight (ww). 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. To understand the importance of life-history type on THg, THg concentrations were measured in isolate, resident and anadromous Northern Dolly Varden from the Babbage River, Yukon Territory, Canada. Differences in mean THg concentrations were found starting at 22 ng/g ww in isolate, increasing to 56 ng/g ww in ...
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