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At least half of the world's killer whale populations are doomed to extinction due to toxic and persistent pollution of the oceans, according to a recent major study.
Although poisonous chemicals, PCBs, have been banned for decades, they are still seeping into the seas. They are concentrated in the food chain; As a result, killer whales, the top predators, are the most contaminated animals on the planet. Worse yet, their high-fat milk delivers very high doses to their newborn babies.
PCB concentrations found in killer whales can be 100 times higher and severely damage reproductive organs, cause cancer, and damage the immune system. The new research analyzed the prospects for killer whale populations over the next century and found that offshore activities in industrialized nations could disappear as soon as 30-50 years.
Among those most at risk are the last corner of the UK, where a recent death revealed one of the highest levels of PCBs ever recorded. Others in Gibraltar, Japan and Brazil and in the northeast Pacific are also in great danger. Killer whales are one of the most widespread mammals on earth, but they have already been lost in the North Sea, around Spain and in many other places.
Orcas hunting seals off the coast of northern Norway.
"It's like the killer whale apocalypse," said Paul Jepson at the Zoological Society of London, part of the international research team behind the new study. "Even in a pristine condition they are very slow to reproduce." Healthy killer whales take 20 years to reach maximum sexual maturity and 18 months to gestate a calf.
PCBs have been used around the world since the 1930s in electrical components, plastics, and paints, but their toxicity has been known for 50 years. They were banned by nations in the 1970s and 1980s, but 80% of the 1 million tons produced have yet to be destroyed and are still seeping into the sea from landfills and other sources.
[mks_dropcap style = ”square” size = ”28 ″ bg_color =” # d0bee2 ″ txt_color = ”# 000000 ″] Banned PCB chemicals continue to severely harm animals, but the Arctic could be a refuge [/ mks_dropcap]
The Stockholm International Convention on Persistent Organic Pollutants entered into force in 2004 to address the problem, but Jepson said cleanup is long overdue. "I think the Stockholm Convention is failing," he said. “The only area where I am optimistic is the United States. They produced 50% of all PCBs, but have been reducing levels consistently for decades. All we've done in Europe is ban them and then hope they go away. "
The researchers said PCBs are just one of the contaminants found in killer whales, with "a long list of additional contaminants known and not yet measured." Other problems for killer whales include the loss of key prey species such as tuna and sharks, overfishing, and increasing underwater noise pollution.
The new research, published in the journal Science, examined PCB contamination in 351 killer whales, the largest analysis yet. The scientists then took existing data on how PCBs affect calf survival and immune systems in whales and used it to model how populations will fare in the future. "The populations of Japan, Brazil, the Northeast Pacific, the Strait of Gibraltar and the United Kingdom are tending to total collapse," they concluded.
Underwater close-up of a killer whale off the coast of northern Norway.
Lucy Babey, Deputy Director of the Orcas Conservation Group, said: “Our abysmal failures to control the chemical pollution ending up in our oceans has caused a killer whale catastrophe on an epic scale. It is essential that the requirements for the safe disposal of PCBs under the Stockholm Convention are legally binding at the next meeting in May 2019 to help stop this scandal. "Scientists have found" extraordinary "levels of toxic pollution even 10 km deep in the Pacific Ocean.
"This new study is a global red alert on the state of our oceans," said Jennifer Lonsdale, president of the Whale Group Wildlife and Countryside Link. "If the UK government is to lead with its proposed Global Environment Act, it must set ambitious targets on PCB removal and protect against further chemical contamination of our waters."
Research shows that killer whale populations in the upper north, off Norway, Iceland, Canada and the Faroe Islands, are much less polluted due to their distance from major PCB sources. "The only thing that gives me hope about killer whales in the long term is that yes, we are going to lose populations in all industrialized areas, but there are populations that are doing reasonably well in the Arctic," Jepson said.
If a global cleanup, which would take decades, can be achieved, these populations could eventually repopulate empty regions, he said, noting that orcas are highly intelligent, have strong family ties and hunt in packs. "It's an incredibly adaptable species - they've been able to [live] from the Arctic to Antarctica and everywhere in between."
He praised the million-dollar "superfund" cleanups in the US, such as the Hudson River and Puget Sound, where the polluter has paid most of the costs: "The United States goes far beyond the Stockholm Convention because they know how toxic are PCBs ”.
Original article (in English)