Ireland’s large whales on the move.

We should continually reassess our understanding of how large whales such as humpbacks use Irish waters; it’s cathartic and serves to remind us that nothing remains the same and the natural world is no different, as it oscillates between constant flux and chaos. So when there is a flurry of humpback whale sightings in the Northwest as occurred last week off the Broadhaven Bay area of Mayo, the question arises as to whether this is at the expense of sightings elsewhere?

During the decade 2001-2010 the only place where you could see humpback whales with any regularity was along the Cork coast……and specifically the west Cork coast.  Of course, this to a certain degree reflected on local observer effort, as back then, Cork benefited from the greatest volume of boat and land based watch effort; and the old mantra applies……” the more we watch, the more we see”.

Table 1.

So, for this first decade of the IWDG’s “Large Whale Project” (now Whale Track) there was a well beaten path by researchers, filmmakers, IWDG members and whale enthusiasts down to the Rebel County.  Despite this, table 1. shows there were still some very quiet years. In fact, in the 12 years 2000-2011 there were three years without a single validated humpback sighting record (2000, 2006 & 2011).  But you’d be forgiven for forgetting this fact, I certainly had, as our memories can be a little selective, besides nobody in west Cork seemed to be overly concerned as its reputation for world class whale watching was based not on the humpback, but on their larger rorqual cousin, the mighty fin whale.

In that 1st decade Co. Kerry had complete annual blanks on 50% of years for humpback sightings.  In time, this changed as the baton was passed from Mick O’ Connell to Nick Massett, who took the concept of dedicated effort watches to a whole new level.  By around 2012, Kerry had the audacity to start challenging Cork’s primacy and over the 2nd decadal period, the humpback data shows a demonstrable shift towards the Kingdom, as IWDG validated more Kerry humpback sighting records than Cork by a ratio of 8 yrs:2 yrs.

Humpbacks were clearly on the move, and they weren’t alone.  The fin whale sighting trend over the same 22-year period 2000-2021 suggests a gradual decline in fin whale activity in Co. Cork, which may have been due to its neighbour to the east, Co. Waterford, where days with fin whales are trending upwards.  But this is a rather crude comparison as it tells us nothing of group size. So a sighting of a single fin whale is weighted the same here as a sighting of 20 fin whales, and it’s a long time since we’ve seen anything like that in West Cork. Many of us recall those late autumn days out on the Holly Jo in 2004 & 2005 where we encountered staggering feeding aggregations of up to 40+ fin whales. It’s hard to imagine this being repeated any time soon here, given the fishing pressure on what’s left of the remaining stocks of their favourite food….sprat.

22 year Fin whale sighting trend Co. Cork V Co. Waterford

So as IWDG enters its 3rd decade monitoring the movements of our large whales in Irish coastal waters, all bets are off as to where the likely hotspots are going to be by the end of this decade.  My feeling, and I hope I’m wrong, is that we in West Cork have lost much of our fin whale activity to the east, while humpbacks have clearly found the rich feeding areas in Dingle Bay and there is evidence that they are now prospecting further up the west coast year on year.  So it’s little surprise that so far this season our only two additions to the Irish humpback whale catalogue (#HBIRL117 & 118 ) are from Donegal and Broadhaven bays in Counties Donegal and Mayo.

As a whale watcher living in west Cork, I am of course disappointed. However, as IWDG Sightings Officer, I’m excited about the prospect of tracking and monitoring the movements of these highly mobile marine mammals in new feeding areas along our western seaboard, where forage fish still exists in sufficient biomass to attract these giants. We’ve said it for years, whales will not return to barren waters. They have options and it looks like some of them at least are starting to explore them.

It is interesting and perhaps a complete coincidence that as I scroll down the long list of 1,360 validated humpback sighting records on the IWDG database, that my eye is drawn to the very first record from Kieran Grace (Birdwatch Ireland) of two humpbacks west of Iniskea South, Co. Mayo on 22nd May 1984.  Perhaps this pair were the real West Coast pioneers and they’ve returned to stake their claim.

Distribution of humpback sighting records (n=1,360) 1984 -2022, Courtesy IWDG.

By Pádraig Whooley
IWDG Sightings Officer