Chemical pollution in cetaceans: PCBs, mercury, microplastics

Cetaceans, predators at the top of the marine food chain, accumulate extraordinary concentrations of pollutants in their fat (blubber) through bioaccumulation and biomagnification. The Southern Resident killer whales of the Pacific (SRKW) hold one of the world records for PCBs in a wild animal. The St Lawrence belugas were officially classified as “toxic waste” by Canadian regulations when they were necropsied.

When the oceans poison their inhabitants

Cetaceans, predators at the top of the marine food chain, accumulate extraordinary concentrations of pollutants in their fat (blubber). The Southern Resident killer whales (Pacific) hold one of the world records for PCBs in a wild animal. The St Lawrence belugas were classified as “toxic waste” by Canadian regulations when they were necropsied. This database presents the contaminants measured for 15 populations.

Going further

Chemical contamination is one of the great silent threats to cetaceans. See the IUCN status of the species, the pathologies of cetaceans (PCBs favour morbillivirus), and the bycatch database.

Persistent pollutants: from the top of the food chain

Cetaceans, as apex predators, concentrate persistent organic pollutants (POPs) along the food chain: PCBs (polychlorinated biphenyls, banned in 1979 but persistent), DDT, brominated flame retardants, PFAS. European killer whales are among the most contaminated mammals on the planet, with PCB burdens exceeding 1,000 mg/kg of lipid, and Jepson et al. (Science 2018) predict their functional disappearance within 30 to 50 years.

Heavy metals, mercury and cadmium also accumulate, in particular in long-lived odontocetes (sperm whale, pilot whale). Microplastics are now detected in stomach contents and even in the blow of whales (Apprill et al.). In females, lactation transfers 60 to 80% of the PCB burden to the first calf, a tragic mechanism that mortgages its chances of survival.