A member of a small group of killer whales was found dead early last year on the Isle of Tiree in Scotland. Over a year on, analysis shows that the creature's toxicity level was exceedingly higher than the accepted level for most marine mammals.
It was January of 2016 when a killer whale was found dead and stranded on the Isle of Tiree in Hebrides, Scotland. The dead adult killer whale was later identified as Lulu, a member of a group of killer whales on the west coast of the country.
Back then, Lulu's cause of death was identified as due to entanglement with a creel rope, but recent evidence shows that there could be another factor that would have killed Lulu even if she had not gotten entangled in the ropes, or perhaps may have led her to live a less than healthy life.
Analysis of Lulu's blubber shows that the killer whale had a polychlorinated biphenyl (PCB) toxicity level that is 80 times higher than that of the acceptable toxicity level for marine mammals. This means that Lulu's health was likely compromised due to the toxic contamination in her body.
PCB Toxicity Affected Lulu's Health
High PCB levels among marine mammals are linked to poor health, increased susceptibility to cancers, a poor immune system, and infertility; some things that Lulu seems to have suffered.
Based on the analysis of Lulu's ovaries, though she was at least 20 years old at the time of her death, an age that is much older than the average age of maturity for the species, Lulu was not able to reproduce in her lifespan.
What worries experts even more is that the group of killer whales which Lulu belonged to was a small group of whales who do not interact with other groups of killer whales, and has not been seen with a calf in their 23 years of observation.
"Lulu's apparent infertility is an ominous finding for the long-term survivability of this group; with no new animals being born, it is now looking increasingly likely that this small group will eventually go extinct," said Dr. Andrew Brownlow from the Scottish Marine Animal Stranding Scheme and veterinary pathologist at Scotland's Rural College.
The Problem With Organic Pollutants
The case of Lulu's death runs similar to a study that was published early this year about how persistent organic pollutants (POPs) are threatening the existence of polar bears. Though POPs have been banned in the 1980s, as the name suggests, its persistence remains to be a problem among humans as well as marine mammals as its effects can be felt even years after production has been halted.
In Lulu's case, the PCB toxicity level found in a sample of her blubber exceeded 950 parts per million (ppm), which is the highest ever recorded in a marine mammal. The findings about Lulu provide further evidence about the adverse effects of POPs and PCBs on marine mammals, and it also shows that certain human acts have a lasting effect on marine creatures, even long after the act itself has been stopped.