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

Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

“…Hg concentrations ranged from 0.001 to 0.62 μg/g; excluding three fish where Hg N0.2 μg/g (two from Paulatuk char, one from Cambridge Bay) Hg concentrations were exceedingly low averaging 0.05 ± 0.02 μg/g over the study area. Hg concentrations at individual sites and times generally were positively correlated (Table S3) with fish length (37 of 49 analyses, 10 significant), weight (34 times, 9 significant), age (40 times, 10 significant) and nitrogen isotope ratio (32 times, 5 significant with one significant negative correlation) as has been observed by others (Gantner et al, 2010a;Lescord et al, 2015;Tran et al, 2015); this indicates that larger, older and fish feeding at higher trophic levels tend to have the highest Hg concentrations. Correlations with carbon isotope ratio were both positive (26 times, 2 significant) and negative (21 times, 3 significant) and for locations such as Cambridge Bay, varied substantially between years possibly reflecting broad feeding patterns in nearshore and offshore locations and benthic and pelagic diets.…”

“…δ 13 C was among the lowest values, (−23.3 ± 0.5‰ and −23.4 ± 1.3‰, respectively) suggesting significant terrestrial carbon sources from the Mackenzie River; similar δ 13 C ratios were observed by Tran et al (2015). However, with terrestrial carbon having a δ 13 C ratio of −29‰ and marine phytoplankton −25‰ (Dunton et al, 2006), marine benthic carbon sources must have been significant as well.…”

“…Where possible, we examined overall population features for evidence of change although not rigorously. We added to the summary data provided by Lockhart et al (2005) by including fish weight from those records and calculating condition factor; we also included additional studies of Hg concentrations in anadromous char located from other studies, most notably from Labrador van der Velden et al, 2015) and the Yukon (Tran et al, 2015).…”

“…In the western NWT, Hg concentrations were determined in Rat River char in 1988 (Tran et al, 2015) and 2003 (this study). Char were somewhat smaller (438 ± 44 mm vs. 452 ± 60 mm) and older (7.4 ± 1.1 years vs. 6.0 ± 0.9 years) in 1988 than 2003 suggesting a higher growth rate in more recent years.…”

“…225 km inland and the closest Yukon coastal community (Wein, 1995); more fishing pressures are exerted from communities to the east in the Inuvialuit Settlement Region (Gallagher et al, 2011). While char stocks have been assessed in several Yukon coastal rivers (Gallagher et al, 2011;Kristofferson et al, 1991b;Sandstrom et al, 1997), Hg concentrations were only recently determined on archived (1988)(1989)(1990)(1991) fish from seven Yukon and three Northwest Territories (NWT) locations (Tran et al, 2015). Hg concentrations were low (site mean 0.03-0.11 μg/g) with highest concentrations at the Firth River where fish were largest and oldest; 62% of the variation in Hg concentration were explained by fork length, age, and δ 15 N. Resident and isolated char in these river systems tend to be smaller, slower growing and shorter lived than anadromous char (Gallagher et al, 2011).…”