The killer whale found dead on a Hebridean beach this week was killed when it became entangle in fishing gear, a post mortem has revealed.
It is the first time a killer whale is known to have died this way in Scotland – and sadly, the Orca had probably been caught up in the ropes for several days.
The whale – known to researchers as Lulu and one of only four females in the group – was discovered beached on the island of Tiree on Sunday.
Lulu was one of a pod of orcas that patrol the waters around the Hebrides and eastern Irish coast. Scientists now believe there are just eight animals remaining in the pod, the only resident orca community in British waters.
In their post mortem report, scientists at the Scottish Marine Animal Strandings Scheme said: “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.”
Entanglement is the most commonly observed cause of death recorded for minke whales in Scottish waters. But the exact numbers and scale are unknown.
There have been at least four whale deaths caused by entanglement in Scottish waters in the past 12 months.