BC Bears Grow Fat On Salmon Rich In Endocrine-Disrupting Chemicals

[hatrack]

Vancouver — Grizzly bears feasting on Pacific salmon provide iconic images of natural bounty that wildlife photographers have captured for generations. But a new study suggests something is wrong with this picture. The grizzly bears in British Columbia that feed heavily on salmon each fall are doing more than loading up on nutrients for hibernation.

Research from the Department of Fisheries and Oceans and the University of Victoria shows that the annual feast of salmon is also loading the bears with pollutants -- including concentrations of chemicals that could affect the reproductive abilities of young females. "These bears are eating seven or eight adult salmon a day, so they can really gorge themselves," said Peter Ross, a marine mammal toxicologist with DFO at the Institute of Ocean Sciences on Vancouver Island and one of the co-authors of the report.

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The paper states that salmon deliver 70 per cent of all organochlorine pesticides, 85 per cent of the polybrominated diphenyl ethers, or PBDEs, and 90 per cent of the PCBs found in the bears. The levels of chemicals in a gram of fat ranged from trace amounts to up to 20 parts per billion for DDT, 43 ppb for PCBs and 53 ppb for PBDEs. Dr. Ross said levels of pollutants in grizzly bears are not as high as those in orcas or polar bears and it is unclear what harm, if any, they might do.

"The total overall picture was that of bears that were not terribly contaminated. The salmon-eating bears had significantly higher levels of contaminants and they had a different pattern of contaminants. . . but I don't think the levels are of significant concern for the health of the animals."

But he said questions are unanswered about the possible reproductive impact some of the chemicals might have if they are concentrated in offspring. Dr. Ross noted that some of the chemicals found in fat samples of salmon-eating bears are endocrine disrupters or hormone mimics. "With low reproductive rates and seasonal cycles of fasting , adult female grizzly bears may supply elevated concentrations of endocrine-disrupting chemicals to their young," states the research paper, which is to be published next month in the journal Environmental Science and Technology.

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http://www.theglobeandmail.com/servlet/story/RTGAM.20050805.wxbears05/BNStory/National/