Home / News / Pollution threatens the future of killer whales

Pollution threatens the future of killer whales

Killer whales are in deep trouble because of persistent chemical pollution in the environment, researchers say.

A new study suggests the long-term viability of more than half of the different orca groups around the globe is now in question.

Some populations, such as those around the UK, the Strait of Gibraltar, off Brazil, Japan and California, are almost certainly doomed.

The assessment is in Science magazine.

The issue is polychlorinated biphenyls, or PCBs.

These chemical compounds were once manufactured in vast quantities, and used in everything from plastics and paints to electrical equipment and sealants. But they are highly toxic and although banned decades ago have amassed in the environment, leaching into the ocean.

Killer whales, or orcas, are top predators so they absorb all the PCB pollution taken in by the different prey in their food chain – from fish, right up to seals and sharks.

The PCBs stunt the ovaries of female orcas, limiting their ability to produce calves. The chemicals also suppress the immune system.

A last refuge for European orcas
‘Shocking’ pollutant levels in UK whale
Banned chemicals persist in deep ocean
What is the outlook for orcas?
The new study models the future of the killer whales’ reproductive success and survivability against the chemical challenge.

For those populations living in clean waters, it is positive. Orcas in places like the Antarctic and the Arctic should increase their numbers.

But for those living in the most polluted seas, the next 30-50 years will be grim.

The killer whales that live on the west coast of Scotland, for example, are now down to just eight individuals and they have not produced a calf in more than 20 years.

Paul Jepson, from the Zoological Society of London, says this group will “disappear in my lifetime”.

“Over 50% of the populations that we’ve got data for will actually collapse in our model,” he told the BBC’s Science In Action programme.

“PCBs are such highly toxic chemicals, and they persist in the environment. And it’s the killer whales that have by a long way the highest exposures now of any species on Earth; certainly any mammalian species.”

Leave a comment

Check Also

Shareholders of Bottlers Nepal (Terai) and Bottlers Nepal Limited (Balaju) to Get Rs. 60 and Rs. 20 Per Share Dividend Respectively; Book Closure Date Yet to be Announced

Bottlers Nepal (Terai) Limited (BNT) has announced dividend of Rs. 60 per share on equity shares ...

Leave a Reply