Archive | May 2017

Killer Whales and bio-accumulation


BBC May 2nd 2017


Lulu was found dead in 2016 on the Isle of Tiree in Scotland

This sad story is about the death in 2016 of one of the few remaining killer whales which live off the western coasts of Scotland. Lulu was estimated to be 20 years old and was washed up dead and entangled in fishing net, on a small Scottish island. The cause of her death is not clear but an autopsy discovered unimaginable levels of accumulated PCB chemicals in her body. Polychlorinated biphenyls have been banned since the 1970’s but are so stable that, although slowly reducing in quantities, they are still very present.

PCB’s are synthetic and were widely used in all sorts of ways mid 20th century, but after their toxicity and tendency to bio-accumulate in food chains was better understood, they were banned. Nevertheless PCB’s remain present in the environment and it will be a long time before they vanish.

PCB’s are known to affect reproduction and can damage the immune and nervous systems. The autopsy of Lulu revealed that she probably had never born calves, perhaps because of the high amount of PCB’s in her tissues. It is also quite likely that she suffered brain damage as a result of PCB toxicity.

8 killer whales remain in the pod (group of whales) off western Scotland and one wonders about the PCB levels in their bodies, and whether this bio-accumulation is sadly a major contributing factor to their slow disappearance and projected extinction.

(This post is an up-date to the page on this blog, comparing bio-magnification and bio-accumulation: