What Killed Lulu the Whale?
May 13 2017 Comments 0
Lulu the Scottish killer whale was one of the last remaining members of the only UK pod known to researchers. Last year, she died after becoming entangled in fishing ropes used to lower and raise creels, which are large cages made of net used to capture crabs and lobsters from the sea.
However, a post mortem on Lulu’s carcass revealed far more worrying findings about the state of her health. Lulu’s body contained an exorbitant amount of PCBs – far in excess of the limit at which damage to marine mammal health is known to occur. Furthermore, tests showed that despite being 20 years of age, Lulu had never once birthed a calf, fuelling fears that her entire pod is destined for extinction.
What Are PCBs?
Polychlorinated biphenyls, better known as PCBs, are harmful toxins which have been known to seriously endanger the health of dolphins, whales and other marine mammals. Once prevalent in the manufacture of electrical equipment, they were finally banned in the 1980s after scientific research unearthed their disturbing health implications.
The contaminants have been known to suppress mammals’ immune system and even contribute to the contraction of cancer. However, perhaps their biggest danger is the ability to make animals incapable of reproduction. As a top-of-the-food-chain predator, killer whales are especially susceptible to high build-ups of PCBs over time.
Even though 30 years have passed since the ban on PCBs in manufacturing, they are incredibly difficult chemicals to break down and have persisted until this day. While there are several techniques for cleaning up PCBs in soil and sediment, achieving the same effects in a substance as expansive and free-flowing as the sea is a more difficult prospect.
In the years after their ban, levels of PCBs in our bodies of water did drop off significantly – but that decline has plateaued in recent years. This has led to some scientists speculating that the contaminants are still finding their way into the ocean from inadequately stored industrial waste.
Extinction “increasingly likely”
Lulu’s body was found to contain concentrations of PCBs at 950mg/kg, which is an incredibly high amount. Damage to marine mammal health is known to occur at just 9mg/kg, meaning that Lulu had over hundred times that threshold in her system.
Unfortunately, such contamination looks to be indicative of a wider trend, rather than just an isolated incident. A 2016 research paper found that on average, north-east Atlantic killer whales carried around 150mg/kg of the toxin in their blubber, causing concerns that they may all be infertile.
Given the fact that not a single calf has been spotted in the 23 years that the pod has been monitored, and that Lulu had not born a calf in her entire life despite being well above the sexual maturity threshold (six to ten years of age), it now looks likely that British orcas are destined for extinction.
“Given what is known about the toxic effects of PCBs, we have to consider that such a high-pollutant burden could have been affecting her health and reproductive fitness,” commented Dr Andrew Brownlow, a veterinary pathologist and head of the Scottish Marine Animal Stranding Scheme.
“Lulu’s apparent infertility is an ominous finding – with no new animals being born, it is now looking increasingly likely that this small group will eventually go extinct. One of the factors in this groups apparent failure to reproduce could be their high burden of organic pollutants.”
Though advances are being made in water turbidity measurement technology all the time, it’s one thing to detect a problem and quite another to solve it. In any case, it looks like it’s too little, too late for the UK killer whale population.
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