A deceased killer whale that had washed up on a Scottish coast had high levels of toxic chemical contamination, scientists say.
The United Kingdom has only one pod of killer whales left, and this pod hasn't successfully reproduced in 25 years. As of now, there are only eight individuals left in the pod that resides of the western coast of Scotland. There are four males and four females, but no calves for a quarter of a century. Scientists fear that this killer whale pod will eventually die out.
Last year, the pod lost an adult female called Lulu. Lulu got entangled in fishing nets, which is just one example of how humans can impact wildlife. An autopsy on Lulu's carcass revealed a more shocking example of the impact of humans on nature.
Tests reveal that Lulu's blubber had shockingly high levels of polychlorinated biphenyls (PCBs), a chemical toxic to humans and animals. PCBs can cause cancer and immune system suppression, and it also accumulates in the fat of marine animals.
Marine animals should have PCB levels lower than nine milligrams per kilogram of body lipids. Amounts above this threshold can cause damage to the animals. Lulu had 950 milligrams of PCB per kilogram of body lipids, which is over 100 times the limit.
The autopsy also revealed that Lulu had never produced a calf. The killer whale was at least 20 years old when she died, which is far older than the onset of sexual maturity. Female killer whales become sexually mature between the ages of six to 10. Thus, it's probable that Lulu may have been infertile. Scientists also think that the PCB contamination may have had something to do with Lulu's infertility.
Now, scientists fear that the eight remaining members of Lulu's pod may also have high levels of PCB. If the other members of the pod had also been contaminated, and the contamination caused infertility, this may explain why the pod had not been able to produce a calf in over 20 years.
PCBs were widely used in electronics and other products for a number of decades. Eventually, scientists found that PCBs were highly toxic to humans and animals. A ban on the use of the chemical took effect in the 1970s and 1980s. Even though it's been decades since the ban took effect, the chemical is still present in the environment.
This is because PCBs are very tough and don't easily break down. Worse, there's evidence that the chemical is still leaking into the environment, possibly due to improper waste containment. Andrew Brownlow, head of the Scottish Marine Animal Stranding Scheme, claims that there are still stockpiles of PCBs in Europe. Once PCBs find their way to seas and oceans, removing them can be near-impossible.
Aside from impairing the immune system, causing cancer, and possibly causing infertility, it's also possible that PCBs can affect brain activity. The chemical may have been implicit in Lulu's death. Killer whales are nimble and intelligent, so the chemical may have impaired Lulu's ability to to dodge fishing nets. Entanglement is rare in the whales, so PCB contamination may have played a part in leading Lulu to her death.
PCB mitigation and decontamination are possible, as the Environmental Protection Agency in the United States has shown. The same efforts can also be successful in Europe and other parts of the world. Sadly, for the last remaining pod of killer whales in UK waters, these efforts are too little, too late. However, decontamination efforts may hopefully be beneficial to future generations of humans as well as wildlife.
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