Yesterday afternoon the phone started ringing from IWDG members in Dublin who had seen a story on social media about killer whales that were filmed from a trawler over the weekend. We made contact with trawlerman James Mac Cluskey who captured this event on his phone and provided us with the following details when he filled in a sighting report for validation online on www.iwdg.ie.
At 13:30 on Sat. 17th Nov., whilst fishing some 6 miles east of Rockabill, Co. Dublin the crew observed and filmed a pair of adult male (bull) killer whales (Orca), which interestingly they felt at the time were hunting. Although difficult to be certain James felt they were hunting either seals or harbour porpoises, suggesting that these are a marine mammal feeding eco-type. The observation took place over a 2 hour period and at times the animals came very close to the trawler which was working at the time and enabled the crew secure video footage of the animals (see image).
James, who from the video clip clearly has a great interest in killer whales and describes them as his favourite animal, had never seen this species before in Irish waters. But his strong impression was that one of them was the individual known as John Coe (W01) from the Scottish West Coast Community group who hail from the Hebridean isles, and are recorded most years in Irish waters. This killer whale pod have been documented previously attacking and killing minke whales off the Minches in Scotland. From the images available to IWDG so far, we feel there is a reasonable chance that James is correct, but important to see if we can get further images which may confirm this link.
Killer whales (Cráin Dhubh) are the largest member of the dolphin familty, and so their common name is something of a misnomer. They are not a new species for Irish waters and since IWDG began collating cetacean records in 
Irish waters over 25 years ago, we have validated 216 killer whale sighting records, which we map here. Although most sightings are along Celtic Sea, western seaboard and North coast, killer whales can show up in any Irish inshore waters and larger aggregations of 100+ individuals have been recorded in offshore waters, when the fish eating eco-type target the seasonal mackeral fishery in the Northwest. Most Irish killer whale sightings occur between April-October, which likely reflects an some observer bias as most people spend more time by, in, or on the sea during this period. From the data available we can confirm that this apex predator has been recorded in all months and so it's not possible to say with certainty whether they have a peak season, in the same way we can with the larger baleen whales such as humpback or fin whales.
This latest killer whale sighting is the second in a little over 2 weeks from North County Dublin, as on 30th Oct. Rory Wilde who was also fishing at the time reported a pair of killer whales further offshore, some 22 miles east of Skerries. Unfortunately, no images were secured from this encounter, so we can't say with any certainty whether these two sighting events are linked, but it is possible.
IWDG would like to extend a big thanks to James Mac Cluskey and his colleagues for sharing this information with us. IWDG ask any members of the public who are fortunate to observe whales and dolphins in Irish waters to assist our conservation work by reporting sightings on www.iwdg.ie.
Video footage of this encounter is available on IWDG's facebook page, although we caution parents of young children that there is some colourful language on it, so we suggest a liberal use of the mute button!
By Pádraig Whooley
IWDG Sightings Officer
PLEASE SUBMIT ALL WHALE, DOLPHIN AND PORPOISE SIGHTINGS AT http://www.iwdg-shop.com/sighting.php?sid=x