Killer whales under threat of extinction from toxic ocean chemicals
At least half of the world’s killer whales will become extinct because of toxic waste in the oceans within the next century according to researchers. Some areas despite efforts to control the pollutants of polychlorinated biphenyls (PCBs) still remain at high levels.
Research scientists from the Zoological Society of London (ZSL) are saying that if we don’t bring down the current concentrations of PCBs it could lead to the disappearance of up to 50% of the killer whales in the next 30 to 50 years. Killer whales have been declining in numbers in 10 out of 19 populations that have been investigated. Newborn whales are rarely seen in the heavily contaminated waters surrounding the UK, Brazil, and the Strait of Gibraltar. This is happening despite the “near global ban” that went into effect over 30 years ago.
When killer whales eat seals and large fish, they ingest the chemicals from them and are among the mammals that have the highest level of PCBs. The mother whales can pass the chemicals onto their off spring through their milk. In the blubber of the killer whales they have found 1300 milligrams per kilogram of PCBs. Some whales may suffer from infertility and their immune system can be damaged with just 50 milligrams. In 1981 these chemicals were banned in the UK and several other countries in the 70’s and 80’s because PCBs decompose very slowly in the environment. In 2004 more than 90 countries pledged to phase out and dispose of the existing stocks of this chemical under the Stockholm Convention.
In the less contaminated waters in the Arctic and the Antarctic the whales seem to sustain growth. Where in the contaminated waters around the British Isles there are only about 10 whales remaining.
Findings show that efforts to eliminate these chemicals is not working and therefore we are in need of further initiatives than those of the Stockholm Convention to protect these killer whales.