100 Killer whales off Ireland and Scotland

Large numbers of Orca have been sighted off Ireland. Photo credit IWDG/© Irish Naval Service, L.E. Niamh

Largest known aggregation of Killer whales in Irish waters

February 2011. IWDG have received a report from the Irish Naval Service of an unprecedented feeding aggregation of Killer whales Orcinus orca in offshore waters off northwest Ireland, some 30 miles off Tory Island. Lt. Cdr. Paddy Harkin, Captain of the L.E. Niamh reports.

"On 27th & 28th Jan 2011 we observed a significant number of Killer whales approx 30 miles West of Tory Island, approx position 55 degrees 30 minutes North 009 degrees 30 minutes West. In one of our photographs upwards of eight Killer whales can be observed in a single photo, an estimate of 10 whales being visible at any one time is on the conservative side. On one occasion at least a dozen Killer whales were within 200 metres of the ship.

Feeding on mackerel shoals
The Killer whales were among large shoals of mackerel, and there were approx 25 fishing vessels mackerel fishing in the area. Large quantities of mackerel were being caught; one foreign fishing vessel had 4,000 tonnes onboard while several others had over 1,000 tonnes, and all fishing vessels were catching in excess of 200 tonnes per day. We observed the Killer whales over a 30 mile stretch of water following the line of the mackerel shoals and fishing effort."

A male Killer whale off northwest Ireland.  © Irish Naval Service, L.E. Niamh.

100 Killer whales
According to Paddy, several of the fishing skippers reported that the Killer whales had accompanied the mackerel shoals and fishing vessels from 57 degrees north, which is to the west of the Hebrides. The fishing skippers estimated that there were over 100 Killer whales in total, and these estimates are consistent with best estimates of the Irish Naval personnel.

Shetland sightings
The first Killer whale sighting on the Irish database was the famous animal nick-named "Dopey Dick" who swam up Lough Foyle in 1977 and enthralled TV viewers as the spectacle played out over a number of days on our TV sets. Since then IWDG has validated 162 records of this apex predator in Irish waters, with an average group size of 3-4 animals per sighting. Although these animals were spread out over a wide area in a lose feeding aggregation, such large numbers have never been documented in Irish waters. That said, similar feeding activity has in recent years been reported by the mackerel fleet off Shetland and the North Sea. Footage of this can be viewed on BBC's Autumnwatch programme.

Despite their name, Killer whales are the largest member of the dolphin family. For further information on this species in Irish waters go to the IWDG website.

IWDG wish to thank Lt. Cdr. Paddy Harkin and other Naval Service personnel on the L.E. Niamh for reporting this important observation to IWDG.