Metal concentrations (AS, CD, CR, PB, HG and SE) in Dolly Varden (Salvelinus malma) from the Aleutian Islands, Alaska

Concerns about contaminants in fish have increased in recent years, especially in species consumed heavily in subsistence diets. Most studies of contaminants in Alaskan subsistence foods have focused on mainland Alaska not the Aleutian Islands. Several islands along the Aleutian Archipelago of Alaska have supported military bases which may be a source of pollution, and the proximity of the Aleutian chain to Eastern Asia may increase its susceptibility to atmospheric deposition of heavy metals. This study compares levels of arsenic, cadmium, chromium, lead, mercury and selenium in the egg, kidney, liver and muscle of Dolly Varden (Salvelinus malma) from Umnak, Adak, and Amchitka Islands in the Aleutian Chain of Alaska. I examined levels as a function of tissue, gender, collection site, and size. There were significant differences in the levels of metals as a function of tissue, with kidney having the highest levels of arsenic and cadmium, and kidney and liver having significantly higher levels of chromium and mercury than the other tissues examined. Selenium and arsenic in muscle and liver were highly correlated with both length and weight of fish. Arsenic and mercury in muscle were highly correlated with levels in liver, kidney and egg. There were few significant gender differences in metal concentrations, with females having higher levels of chromium in muscle and cadmium in kidney than males. However selenium in liver was higher in males than females. On Amchitka mean mercury levels were higher in both muscle (149 ppb; ng/g, wet weight) and liver (321 ppb) compared to fish from Adak and Umnak (muscle = 24 ppb and liver = 44 ppb). Dolly Varden collected from Cannikin Lake and Fox Lake on Amchitka were probably not sea run. This may explain the elevated mercury levels found in Dolly Varden from Amchitka Island. Landlocked Dolly Varden feed more heavily on smaller fish and fish eggs which places them at a higher trophic level than anadromous fish which primarily feed on amphipods. Selenium levels were highest in muscle (761 ppb) and liver (1,860 ppb) of fish caught in Cannikin Lake on Amchitka Island. Overall, concentrations of the metal contaminants in Dolly Varden were relatively low when compared with other studies on anadromous and marine fish from the region, and differences among collection sites may be due to trophic level differences between landlocked (Cannikin Lake) and sea-run Dolly Varden.