Report finds dead whale at Loch Fleet drowned after becoming entangled in fishing gear
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A dead whale that washed up on a sand bank in Sutherland suffered an agonising death after becoming snared in fishing gear, a report has revealed.
It added that there is now "a real concern that mortality due to entanglement is having a significant impact on the populations of humpback whales in Scottish waters".
The juvenile humpack was found on a sand bank at Loch Fleet nature reserve, in Sutherland on May 4.
The Scottish Marine Animal Stranding Scheme (SMASS) said today that there has been a "spate of fatal entanglements" reported to it this past few weeks.
"We are confident the cause of death was drowning due to entanglement, and based on the lesion pattern, most likely in rope around 12mm in diameter," said SMASS.
"No rope remained attached to the carcase - only abrasions and bruising where the rope had dug into the skin remained. The extent of these lesions suggested the animal had struggled to get free for several hours before running out of energy and drowning.
"There was around 100 litres of fluid around the lungs, likely aspirated seawater. This young animal was otherwise in very good body condition and had been feeding well but not recently.
"This was also not the first time the animal had been entangled- there was evidence of old, healed entanglement scars on the tail and tailstock entanglement where lengths of rope which had dug into the tailstock and abraded twin linear lesions on the underside of the tail fluke. Somehow, the animal had become free and the wounds had had time to heal, this time sadly it was not so lucky.
"As with many of the entanglement cases reported to SMASS, carcases wash up without any material attached - it seems they are cut out at sea and only tend to wash up when there is an onshore wind. Although we can’t be 100 per cent positive about the origin of the rope which entangled this animal, the patten would be highly consistent with creel rope.
"Humpback entanglements reported to SMASS are rare - fewer than 20 cases over the past decade- but, of those we were able to examine, entanglement was the cause of death in every single one of them.
"Recent work undertaken by the Scottish Entanglement Alliance collaboration estimated that around 95 per cent of entanglements go unreported. There is also a real concern that mortality due to entanglement is having a significant impact on the populations of humpback whales in Scottish waters.
"To reiterate the point made in the paper - Scottish creel fishers have shown a willingness to engage in entanglement mitigation, and there are options being explored to limit the harms caused to marine mammals, for example, the introduction of sinking groundline to the creel sector. The entanglements we’ve had recently have been attributed to both creel fishing and other fishing activities, so it is clear work on this wider picture is urgently needed."
Humpback whales were once hunted to the brink of extinction in Scottish waters, but in recent years the Hebridean Whale and Dolphin Trust has noticed an increase in the number of sightings.
It is unknown whether this represents a genuine increase in population size, a range shift into Scottish waters, or more vigilant reporting from members of the public.
Humpback whales are at high risk of entanglement in ropes and lines in the water - including the giant snared in fishing gear at Helmsdale, Sutherland, in 2015 and used by TV adventurer Ben Fogle as "bait" to see if he could prove great white sharks visited UK waters.
Humpback whales have the largest forelimbs in the animal kingdom – leading to their scientific name Megaptera, meaning “giant winged”. They have 19 feet long flippers which make them prone to snagging ropes. Given that they cannot swim backwards, a simple entanglement can be fatal or lead to prolonged suffering.
The whales travel thousands of miles from warm-water breeding grounds in the tropics to the cold-water feeding grounds in the polar regions. They favour inshore waters and continental shelf areas, but will travel through open water during their migration.
They are usually encountered in the Hebrides travelling between breeding grounds off Africa to feeding grounds around Iceland and Norway.
More than 30 whales are snared by fishing gear in Scotland every year, said research published earlier this year.
Entanglement is known to be the largest identified cause of death due to human activity for minke and humpback whales in Scottish waters. However, the extent of the issue was not previously well understood.
The Scottish Entanglement Alliance brought together government, academia, NGOs and the fishing industry.
During the project, commercial creel fishermen from all around the Scottish coast were interviewed and their contribution allowed the researchers to better understand the nature and extent of entanglements in Scotland’s waters.
The findings were published in the journal Endangered Species Research. The study estimated that in Scottish waters approximately six humpback whales and 30 minke whales become entangled in creel fishing ropes each year.
Other marine species such as basking sharks and dolphins were also recorded to have been entangled. Not all entanglements are fatal. However even those entanglements which are not fatal can potentially pose a serious welfare problem.
And cumulatively the number of entanglements may have "a significant impact" on small populations and "a devastating impact" on the individuals concerned.
However researchers discovered that the fishers found the experience of catching a cetacean "very emotional" and their "main concern" was for the welfare of the animal.
