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IWDG/Vimeo
Andy Smith and Dermot Henry shared video footage with IWDG.
# Co Louth
First case of grey seal preying on a harbour porpoise recorded in Ireland
The incident was documented off Co Louth last month.
THE FIRST CASE of a grey seal preying on a porpoise has been recorded in Ireland, according to the Irish Whale and Dolphin Group (IWDG).
The report initially came in on Sunday 14 November from Clogher Head in Co. Louth.
The man who witnessed the incident, Andy Smith, happened to be fishing off the pier as it played out. He contacted the IWDG about it and shared video footage of the attack.
Smith said he and another man saw a porpoise calf killed by a large male seal, something IWDG said was a “rare event” in Irish waters, adding that it was “rarer still” to capture it on video.
“Thankfully there were no kids around to witness it. Nature raw in tooth and claw I suppose,” he told Pádraig Whooley, the IWDG Sightings Officer.
Having inspected the footage, IWDG said an adult male grey seal can be seen with a harbour porpoise in it’s mouth.
“The seal appears to be attempting to drown its victim before commencing to feed on it,” Whooley said.
While this may be a rare sight in Irish waters it’s not all that uncommon abroad.
An eight year study published in the Proceedings of the Royal Society B journal of biological science back in 2015 exposed grey seals as a major predator of other harbour species.
The cause of many porpoise remains washing up on beaches in the Netherlands was previously unknown, but it was revealed grey seals were preying on them.
That meant seals, and fishing “bycatch” (catching a species not originally intended in fishing nets and causing injury or death) were two of the biggest risks to porpoises off the Netherlands.
The Irish Whale and Dolphin group says this raises many questions about grey seal behaviour here:
- Is this a new behaviour for Irish based seals?
- Is it an established behaviour that’s just never been filmed before?
- Could the grey seal involved in the attack be resident here, or have migrated from abroad?
- Is this one grey seal that picked up this behaviour likely to pass it on to others?
- What are the implications of this for the harbour porpoise population at Clogher Head, and particularly North Dublin as it has a high density population.
