Industrial Contaminants

Persistent Organic Pollutants in Marine Mammals

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Some killer whales on the B.C. coast have high levels of contaminants in their body fat.

Persistent organic pollutants (such as PCBs and PBDEs) in the ocean accumulate in the marine food chain as smaller organisms are eaten by larger predators. Research shows that:

• Transient killer whales are the most contaminated [more about killer whales]. This is probably because they eat seals and other marine mammals, and therefore feed higher up the food chain than resident killer whales, which eat fish.

• The southern resident whales are more contaminated than northern resident whales, even though their diets are similar. The southern residents likely eat more contaminated fish from the industrialized areas of B.C. and Washington.

• Male killer whales are generally more contaminated with PCBs than females. Females shed some of their body burden of contaminants when they give birth and nurse their young.

• PCB contamination in harbour seals (not shown on graph) varies regionally. Seal pups from Puget Sound have levels of PCBs five times higher than pups from the Strait of Georgia. Pups from Queen Charlotte Sound are the least contaminated.

• The effect of levels of PCBs and PBDEs found in marine mammals is not known.

For detailed information, including graph data, see In-Depth report [pdf].

Next: Persistent Organic Pollutants in Blue Heron and Cormorant Eggs