The necropsy of 'Lulu', from the UK's West Coast Community orca population, has revealed that she most likely died as a result of entanglement - this is tragic news and is another stark reminder of the polluted state of our oceans. There may be as few as eight individuals left in this population and no calves have been produced since studies on these individuals began.
In a statement released by the Scottish Marine Animal Stranding Scheme (SMASS), team members Dr. Andrew Brownlow, Nick Davison and Mariel ten Doeschate have said,
A very unfortunate but interesting first necropsy for 2016. We’re out on the Isle of Tiree at the moment having necropsied an adult female killer whale (Orcinus orca). This animal has been identified as ‘Lulu’, one of the animals from the Scottish west coast community. By the time we had heard of her stranding and travelled to Tiree, she had been dead for 4 days, so much of the internal organ structure had been lost. Nonetheless we found convincing evidence that she had become chronically entangled and this was the most likely cause of her death. There were deep, granulating wounds around the tailstock and tell-tale twin linear abrasions on the underside of the tail fluke. These are consistent with a rope wrapping around the tail and trailing behind the animal, probably still attached to something at the other end. This would have made normal swimming very difficult, and we suspect the animal had been entangled for several days. She hadn’t fed recently but had swallowed a large amount of seawater, most likely as she eventually succumbed to the entanglement and drowned.
There were no ropes or gear left on the carcase; we’re assuming all this from the lesions we found on her body, so we don’t know if this was due to active fishing gear, abandoned or ‘ghost’ gear, or other marine debris. The lesions are very similar however to those we see from creel rope entanglement in baleen whales. This is the first killer whale we have seen which has been entangled, although we have had an increase in entanglement incidence in other large cetaceans over the past year.
These types of mortality are particularly tragic, however from examining this case we should be able to learn a little more about a poorly understood population. We have samples to examine age, reproductive status and pollutant burden, and this will form part of future studies.
Andrew, Nick and Mariel
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