First ever live Sei whale sighting off Ireland

28/09/2009 09:08:17 1st Sei whale sighting record validated in Irish waters - Courtesy of the Irish Whale and Dolphin Group
September 2009. The Irish Whale and Dolphin Group (IWDG) are delighted to confirm the 1st validated Sei whale sighting in Irish waters.

On Wed. 23rd September 2009 IWDG member, John Brittain, based in Clifden, was at sea on an angling charter in quite poor sea conditions east of Inisboffin Island, Co. Galway, when they observed and photographed a whale of more than 30 feet long, with a visible blow.

Eager to establish which species the whale was, John forwarded an image to IWDG. It was an excellent head shot, which was fortunately taken from the right side, and showed an open mouth, rostrum and dark baleen plates. At a glance IWDG ruled out its being a fin whale, as there was no evidence of the diagnostic white baleen plates found towards the rostrum tip on the right side of a fin whale's head.

Too large for a Minke
Although not a huge whale, this was a large whale, and appeared too large to be a Minke whale. There are some very large Minke whales out there and no doubt a small percentage may be more than 30ft in length. However the curved rostrum was inconsistent with Minke whale, which tends to be flat in profile. Minke baleen plates are pale or creamy. So on a number of counts, the Minke whale was also removed from the list of possibles.

Not a Bryde's whale
Being able to remove both Minke and fin whales really only left one real contender, but IWDG still needed to eliminate an outsider, the Bryde's whale. This rorqual has a more warm water distribution and is unique in having a series of three rostral ridges running from the blow hole along the length of the rostrum; in sharp contrast to all other rorquals which have a single ridge. So they could also remove Bryde's whale from their enquires, clearing the way for them to announce with confidence that this is a Sei whale, Balaenoptera borealis.

Sei stranding in 2006
Although never previously sighted in inshore Irish waters, there are three stranding records of this species; the last of which was a well publicized live stranding in Larne, Co. Antrim in July 2006 which was euthanized. Go back a further 92 years and there was another stranding record of this species in 1914, which demonstrates that this species rarely enters Irish inshore waters. There is always the possibility that this species is misidentified under normal field conditions, it is almost always assumed that every large whale with a visible blow seen in Irish waters is a fin whale. On reflection, this could be erroneous.

Better photos required
So the presence of Sei whales off the Irish west coast is an intriguing development, and places an onus on those of us fortunate enough to observe large whales to re-double our efforts at describing as much possible diagnostic detail as possible .....or alternatively make sure you've a decent camera on board and forward relevant images to IWDG.

Other possible sightings
IWDG had heard through the grapevine, mention of Sei whales in the past few weeks off the Broadhaven area of Co. Mayo. But as of yet they've received no details of these sightings which remain unproven. Any further Sei whale sightings are crucial in helping them piece together the few scraps of data that exist on this species in Irish waters.
So if you feel you've observed this species or have any images of what you think might be Sei whale around the Irish coast, IWDG would love to hear from you, so that they can try to establish a "bigger picture"....if indeed there is a "bigger picture" regarding this species in Irish waters.

Click here to go to the IWDG website