Killer Whale Post Mortem Suggests Entanglement in Fishing Gear

Published Wednesday, 13th January 2016 in Veterinary Services news

Killer whale found stranded on the Isle of Tiree

SRUC vets believe that a female killer whale recently found stranded on Tiree, died as a result of entanglement in ropes, likely to be either active or abandoned fishing gear or creel lines.

A post mortem was carried out by Dr Andrew Brownlow and his team from Scotland’s Rural College (SRUC) which coordinates the Scottish Marine Animal Stranding Scheme (SMASS).

Identified as ‘Lulu’, the adult orca was from the only pod of resident killer whales in the UK, living off the Scottish west coast. This small population consists of nine whales, dubbed the ‘West Coast Community’, and never interact with the migratory pods and never has a calf been recorded within the group.

This is the first killer whale which the SMASS team have seen entangled however there seems to be an increase in the number of entanglement cases in other large cetaceans over the past year.

Commenting on the likely cause of her death, Dr Brownlow advised:

“We found convincing evidence that she had become chronically entangled and this was the most likely cause of her death. The deep wounds and abrasions we observed are consistent with 10-15mm rope, likely still attached to gear of some sort, wrapping around the tail and dragging behind the animal.

“Normal swimming and foraging would have been made very difficult and we suspect the animal had been entangled for several days. There was a lot of seawater in the stomach and we suspect she eventually drowned because of the entanglement. Although there were no ropes or fishing gear left on the carcase, the lesions are very similar to those we see from creel rope entanglement in baleen whales.

“Although deaths such as this are particularly tragic, we will be able to carry out further research and investigations on this animal which should enable us to learn more about a poorly understood population. The samples we have recovered can tell us the orca’s age, whether she has ever been pregnant and possibly indicate any contaminant burden. Marine pollution and the effects this has on the health of marine mammals is an ongoing area of research for SMASS.”

Every year over 500 marine mammals are stranded around the coast of Scotland and any cases suitable for post mortem are examined by the team based in Inverness.

All dead strandings should be reported to the Scottish Marine Animal Stranding Scheme. The strandings project was set up in 1992, led by SRUC, funded by Marine Scotland and supported by 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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