Killer Whales: Extinction Risk Off Europe?

Killer whales, the charismatic and toothy black-and-white whales, can live up to 100 years. But they might be at risk of extinction off Europe's industrialized areas, because chemicals that were long-ago banned continue to leach into the seas, scientists said in a recently published study.

The study was conducted by researchers from Spain, Portugal, Ireland, Slovenia and the United Kingdom. It took blubber samples from 1,000 dolphins, porpoises and killer whales. The scientists are asking for stronger disposal rules for polychlorinated biphenyl (PCBs) used in paints, construction and electrical equipment until the 1980s.

"It's really looking bleak...We think there is a very high extinction risk for killer whales as a species in industrialized regions of Europe," Paul Jepson of the Zoological Society of London and lead author on the study, said to a telephone news conference, according to a Reuters article.

According to the findings, concentrations of PCBs in blubber from killer whales, striped dolphins and bottlenose dolphins off Europe were within the highest recorded in the world.

Harbor porpoises, the fourth species in the study, scored lower levels.

PCBs typically drain into rivers from unsealed dump or storage sites. Then they are eaten by mussels and crabs, which are eaten by fish -- the sustenance of predators including killer whales.

Once the PCBs reach the marine mammals, they take residence in and store up in the blubber. It's even possible for PCBs to be transferred to the young via their mothers' milk.

Worldwide, killer whales live in many areas, including the Arctic and Antarctica, far away from pollution sources.
The study authors urge action to set stronger restrictions in Europe, or else: "PCBs will continue to drive population declines or suppress population recovery in Europe for many decades to come," according to the report.

Maybe because the U.S. Congress banned PCBs in 1979, levels of the chemical in killer whales in United States waters are not as high as those in Europe. Only as late as 1987, PCBs were banned in nations along the Mediterranean.

This study's samples came from populations off the United Kingdom, Ireland, the Strait of Gibraltar and the Canary Islands in Spain.

The results were published in the journal Scientific Reports.

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-Follow Catherine on Twitter @TreesWhales