Largest fin whale aggegation of year goes to....

16th Mar 2011 After a casual chat with Colin Barnes yesterday, following a conversation he had with Micheal Walsh, we got sketchy details on what sounded like an amazing encounter by commercial fisherman, John O' Mahoney who fishes out of Kinsale on the MVF Sean Marr II.

After a chat with John this morning, we can confirm that the largest fin whale group of the 2010/11 "large whale" season was on 21st Jan, when he observed a minimum of 30 fin whales some 6 miles WNW of the Western rig at the Kinsale Gas Fields, Co. Cork. Interestingly, John's boat at the time was catching mackerel, a species we don't normally associate with fin whales. That said, John did clarify that his large mesh size may have allowed herring to escape.


In John's own words...." there were powerful spouts errupting everywhere both close to his boat and off in the distance". John's initial thoughts were these were humpbacks, but we are confident based on the numbers, their large size 60-70ft, tall blows, dorsal fins and absence of tail-fluking/breaching, that these were fin whales. This sighting is one of the largest fin whale aggregations ever recorded in any Irish waters, inshore or offshore and is certainly the largest group size of the 2010/11 season.

Unfortunately, this activity has come to our attention too late to derive any research benifits in terms of Photo ID (IWDG) or biopsy sampling being carried out by Conor Ryan, (GMIT), but better late than never. It's great to be able to add this record to the Irish Cetacean database retrospectively.

In the 2004 Large Whale season similar large numbers of 30-50 fin whales were routinely recorded from the Holly Jo in offshore West Cork waters during November, and so these large aggregations are not without precedent. A quick glance on the Advanced Search facility of www.iwdg.ie shows that fin whales were also recorded off Roche's Point, Co. Cork and off Waterford/Wexford on Jan 21st, showing just how widespread and numerous the planet's second largest creature can be along the Irish South coast during the season.

Alas, with no validated records of large whales since 10th Feb, they are assumed to have left their South coast feeding grounds. We'd really not expect to monitor their return for a few months, as Andrew Malcolm in recent years has generally detected the 1st fin whales of the year as early as late May from Ram Head, Co. Waterford. That said, Nick Massett did have his first minke whale off Slea head this week, and there also seems to be good numbers of inshore common dolphins off Kerry, West Cork and East Waterford at present.

So fingers crossed that the stretch in the days and the sun's increased intensity and warming seas will kick start the early phytoplankton blooms which will also attract the 1st basking shark sightings of the year, which can be seen as early as late March. The quiet before the storm!

As our online submissions form is still out of commission, we'd ask all recorders to email the relevant sightings to IWDG at sightings@iwdg.ie

Pádraig Whooley

Sightings Co-ordinator