Rare Sei whale record off Ventry, Co. Kerry

16th Sep 2014

On Friday morning September 12th  I was in a bit of a rush to catch the Cape Clear ferry for the IWDG’s September whale watching weekend course, when Nick Massett’s caller ID flashed on my phone and I thought....better take this, and was glad that I did. Nick was certain that he was watching a sei whale Balaenoptera borealis that morning within 150 metres of Ventry beach, Co. Kerry, and the more he described its behaviour and features the more certain I was that he was indeed describing one of the most elusive large whales in Irish waters.

There is probably not a person in the country who has observed more minke whales than Nick in the past decade and he was certain based on its large size and blow alone that the smaller minke could be eliminated. Similarly, none of its physical features or behaviours pointed to the larger fin whale.  The images that arrived over the weekend indeed confirmed this to be a sei whale, based on a combination of features which included: length (12 mts), large visible blow, baleen plates were similarly coloured on both left and right sides (image below), and most importantly the rostrum had a downward curve at the tip (image above). Its behaviour too was significant in determining species, as Nick observed it skim feeding on the surface, something akin to that of a basking shark.   

Sei whale baleen lacking the asymmetric colouration of the larger fin whale © Nick MassettTo put the significance of this latest sighting from the Slea Head peninsula into context, this is only the 5th record of a sei whale on the Irish sightings database, but as four of these were of the same animal that was photographed between 11th and 23rd Sept 2009 between Eagle Island, Co. Mayo and Inisboffin, Co. Galway, it could equally be treated as only the 2nd validated sei whale sighting event on the database. It is too early to say with such a small sample size, whether it is significant that these sei whale sightings are all in September; but this latest sighting is a timely reminder that we should never assume that all baleen whales that are neither minkes nor humpbacks, are fin whales.

It has often intrigued us that with over >1,000 validated sightings of fin whales along the Irish South coast, many with supporting images, that sei whales appear to be all but absent, and so clearly sei whales are rare or at least rarely seen in our inshore waters. The current distribution of sei whale sightings does suggest that they may be more prevalent along the western seaboard, and may be one to watch out for in future for  whale watchers anglers and boatmen working inshore along the West Coast.

Thanks to Nick Massett and Mick Sheeran

Editor's note....in the past four days, Nick notes that he has also observed minke whales, a returning humpback (#HBIRL17) now a 4th inter-annual re-sighting, a fin whale, as well as this rare sei whale record.  Four whale species in less than a week from one site.....is likely to be something of an Irish record.

Pádraig Whooley, IWDG Sightings Officer

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