Environmental Trends 2007

Contaminants

Persistent Organic Pollutants in Tissues of Marine Mammals

Persistent organic pollutants (such as PCBs and PBDEs) continue to accumulate in the marine food chain for decades after measures to curtail emissions have taken effect.

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

Sources: Compiled from Rayne et al. 2004 and Ross et al. 2000.

• Transient killer whales have the highest levels of contamination – likely because they eat seals and other marine mammals, and therefore feed higher up the food chain than resident killer whales, whose diet consists mainly of fish.

• Photo credit: B.C. Parks

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

• PCB contamination in harbour seals varies regionally (not shown). The PCB levels found in seal pups from Puget Sound are five times higher than in pups from the Strait of Georgia. Pups from Queen Charlotte Sound show the lowest levels of contamination.

• The effect of levels of PCBs and PBDEs found in marine mammals is not known, but concentrations in most whales are higher than levels known to cause immunotoxicity in seals.

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

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