Organochlorines in steller sea lions (Eumetopias jubatus) from the western north Pacific

Organochlorines in steller sea lions (Eumetopias jubatus) from the western north Pacific

H. Hoshino, S. Fujita, Y. Goto, T. Isono, T. Ishinazaka, V.N. Burkanov, and Y. Sakurai

Organochlorines in steller sea lions (Eumetopias jubatus) from the western north PacificThis is part of Sea Lions of the World
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Description

The population of Steller sea lions, Eumetopias jubatus, has declined in the western North Pacific since the late 1960s. Recently, the Sea of Okhotsk was reported to be polluted by organochlorine contaminants (OCs) including polychlorinated biphenyls (PCBs) and agrochemicals. OCs are known to have toxic effects on phocid species; thus, studies of OCs in sea lions are important for sea lion conservation.

In this study, sea lion blubber samples were collected from the Kuril Islands and Olyutorsky Bay in Russia and Hokkaido in Japan from 1997 to 2004, and OC concentrations in blubber were measured.

1,1′-(2,2,2-trichloroethylidene)bis(4-chlorobenzene) and its metabolites (DDTs) and PCBs were found to be the dominant compounds accumulated in sea lions of the western North Pacific. The DDT and PCB levels were higher in Steller sea lions from Hokkaido than in sea lions from Olyutorsky Bay. The ratio of DDTs to PCBs in sea lions from Hokkaido was also higher than in sea lions from Olyutorsky Bay. A higher number of adult sea lions from Hokkaido exceeded the 2,2′,3,4,4′,5,5′-heptachlorobiphenyl level reported to decrease circulating thyroid hormone in ribbon seals than sea lions from Olyutorsky Bay. DDTs and PCBs were the predominant OCs accumulated in Steller sea lions of the western North Pacific measured in this study. In particular, Steller sea lions from Hokkaido may have higher DDT accumulation than sea lions in the western Bering Sea and may have higher risks of toxicity.

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