Tiree killer whale was poi­soned with toxic PCBs

The Oban Times - - News -

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.

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