Organochlorines in walleye pollock from the Bering Sea and southeastern Alaska

Organochlorines in walleye pollock from the Bering Sea and southeastern Alaska

R. Heintz, M.M. Krahn, G.M. Ylitalo, and F. Morado

Organochlorines in walleye pollock from the Bering Sea and southeastern AlaskaThis is part of Sea Lions of the World
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Description

The ubiquitous distribution and toxicity of organochlorines in high latitude food webs has been suggested as one factor in preventing the recovery of the western Steller sea lion stock. However, there are few data describing the bio-availability of these contaminants in the sub-arctic Bering Sea and Gulf of Alaska. We measured concentrations of dioxinlike and other selected polychlorinated biphenyls (PCBs), DDTs, and hexachlorobenzene (HCB) in a prey species of Steller sea lions (walleye pollock) that is distributed throughout the range of these marine mammals, to test the hypothesis that contaminant loads in western stock food webs would be higher than those of the eastern stock. More than 110 fish were collected from six regions: western Bering Sea, western Aleutians, eastern Aleutians, Pribilof Islands, northern Bering Sea, and southeastern Alaska. Organochlorine levels were found to correlate with fish age and size (r2 > 0.390), but were uncorrelated with lipid content. Pollock from southeastern Alaska were significantly more contaminated than Bering Sea pollock (P < 0.01) with length-corrected concentrations of 5.00 ng per g wet weight, 4.93 ng per g, and 1.15 ng per g for total PCBs (ΣPCBs), total DDTs (ΣDDTs), and HCB, respectively. Aerial transport and precipitation likely account for the relatively high levels of contamination in southeastern Alaska. Eastern stock sea lion populations have been increasing while apparently consuming prey with higher organochlorine loads. Consequently, presence of organochlorines in high latitude food webs does not appear to be a major factor inhibiting the recovery of the western sea lion stock.

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