The first case of a grey seal predation on a harbour porpoise in Irish waters has been confirmed, the Irish Whale and Dolphin Group (IWDG) says.
Video of the incident off Clogherhead in Co Louth on Sunday 14 November was submitted to the marine wildlife charity. It appears to show an adult grey seal with a porpoise calf in its mouth and attempting to drown its victim before feeding on it.
Sightings officer Pádraig Whooley said there was “little doubt” as to what was occurring in the footage, which can be seen below. Some viewers may find the video disturbing:
Andy Smith, who was fishing on the pier in Clogherhead when he shot the video, said: “We initially saw the mother and baby about 200m out to sea but about 20 minutes later the seal surfaced with the baby porpoise in its mouth.
“It was quite violent and bloody. Thankfully there were no kids around to witness it. Nature raw in tooth and claw I suppose.”
Whooley added that the incident, while rare, is not without precedent. A paper published in the journal Marine Mammal Science in 2014 offered the first evidence of grey seal predation on harbour porpoise in the English Channel and North Sea.
“However, this behaviour has never before been documented in Irish waters, which is surprising given the large populations we have of both coastal species,” he said.
The incident now opens questions as to whether this is indeed new behaviour from an Irish seal “or one that has simply never before been witnessed or recorded in Ireland”.
In addition, it is not confirmed whether the seal in the video is from an Irish resident population or one that travelled here from the North Sea area.
Whooley also posits: “What are the likely implications at population level for the resident harbour porpoises of Clogherhead and beyond? Especially given that areas like north Co Dublin have some of the highest densities of porpoises in Irish waters.”
