Tiree killer whale was poisoned with toxic PCBs

THE POST-mortem examination on a killer whale washed up on beach on Tiree last year has found it to be the ‘most contaminated on the planet’, leading scientists to predict its pod living off Scotland’s West Coast will become extinct.

The Scottish Marine Animal Stranding Scheme, managed by Scotland’s Rural College (SRUC), found the killer whale had one of the highest levels of polychlorinated biphenyl (PCB) pollution ever recorded.

The adult killer whale – identified as a well-known animal named ‘Lulu’ – died after be- coming entangled in creel rope in January 2016, but subsequent analysis undertaken over the past year has shed further light on her case.

The SRUC statement explained: ‘Analysis of Lulu’s blubber revealed PCB concentrations 100 times higher than the accepted PCB toxicity threshold for marine mammals. High PCB levels are linked to poor health, impaired immune function, increased susceptibility to cancers and infertility.

‘Work undertaken in collaboration with the University of Aberdeen found Lulu was at least 20 years old. Based on analysis of the ovaries, it appears that she never reproduced, despite being much older than the average age for maturity in killer whales.

‘These findings do not bode well for Lulu’s small pod. This small group is usually seen off the West Coast of Scotland, and numbers only eight individuals. These individuals never interact with other groups of killer whales, nor has a calf been recorded within the group in the 23 years it has been monitored.’

Dr Andrew Brownlow, head of the Scottish Marine Animal Stranding Scheme and veteri- nary pathologist at SRUC, said: ‘Previous studies have shown that killer whale populations can have very high PCB burdens, but the levels in this case are some of the highest we’ve ever seen. We know Lulu died from becoming entangled, but, 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.

‘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. One of the factors in this group’s apparent failure to reproduce could be their high burden of organic pollutants.

‘Once PCBs get into the marine environment, they are difficult, if not impossible, to remove. They accumulate through food webs and persist over time.’

The SRUC also said there was a growing concern among many cetacean scientists that, unless a more proactive approach is taken to assessing and decontaminating PCB-contaminated sites to stop these pollutants leaching into the marine environment, then the effects seen with this small group of killer whales on the west of Scotland could become evident in many more iconic marine mammal species.

All dead strandings in Scotland should be reported to the Scottish Marine Animal Stranding Scheme (www,strandings.org).

The strandings project was set up in 1992, led by SRUC, funded by Marine Scotland and DEFRA. The project aims to collate, analyse and report data for all marine mammals (cetacean and seals), marine turtle and basking shark strandings.