Basking shark bonanza in Northwest

23rd May 2013

Report Update: 25 May 2013

Great to see Northern Ireland get on the basking shark score board (especially afer the day's rugby defeat) with the first record of the season for the provence going to White Rock's beach, Portrush, Co. Antrim, where a single shark was recorded 25/05/13.

 

Report Update: 24 May 2013

Another half dozen feeding basking sharks this morning off Kilcummin Head area of Killala Bay by Seamus Tuffy. So still no let up in this activity.

 

Report 23 May 2013

Historically the basking shark season is a late spring early summer affair in Irish waters, of course there are always likely to be a few outliers that arrive early and stay late, but the vast majority of sightings are between April-July. The peak period is pretty well right now, May/June.

The trend in the past three years has been a decline in basking shark sighting records reported to IWDG, and this trend looks set to continue in 2013. So far this year IWDG has validated 19 basking shark sighting records, while for the same period in 2012 this figure was 84, 105 records in 2011 and 81 records in 2010. So the figures do point to a steady decline in sightings in recent years, but it is too early to speculate on the drivers that may be underpinning the decline. While of course it is entirely possible that this cycle is following a very natural "boom-bust" model. 

The season so far has been interesting as depite the relatively low number of sightings, we can see that it's shaping up to be a season of two halves, with almost all sightings in April coming from the south and southwest coast, while most May activity has come from the Northwest area.  The 30 mile stretch of coastline between Downpatrick Head, Co Mayo, extending east into Killala Bay and then crossing to Streedagh Point in Sligo Bay have produced a fantastic run of near daily basking shark activty with reports to IWDG suggesting that Killala bay may have >30 sharks.  Other noteworthy activty were estimates of 15 sharks off Tory Island, Co. Donegal on 6th May, and 12 off Slea Hea, Co. Kerry on 11th April.

A few things just to remind recorders of......minke whales are occasionally seen in areas where there is basking shark activty, although the minkes are clearly feeding further up the food chain on sprats or sand eels, so keep your eyes peeled for this small baleen whale, which is in the same size range as the basking shark. Also, without labouring the point again this year, people often assume that any large animal jumping (breaching) out of the water has to be a whale, we urge caution here.

How to distinguish a breaching whale from a breaching basker?

If the following scenario best describes your observation, then it is more likely that what you saw was a basking shark.....You have been either watching an area from land or from a platform with no evidence of the presence of an animal.  You then observe a sudden, explosive breach and subsequent re-entry splash of a very dark, streamlined animal of c15-30ft length. There is some debate as to whether basking sharks “multiple” breach, and there is evidence that yes, basking sharks can and do breach more than once.  Once the breaching activity has ended, despite your scanning the area for the animal to resurface, there are no subsequent re-sightings within 15 minutes after the observed breach.

Such a sighting would suggest to us that what you saw was a basking shark.

Sightings of “breaching whales” are very different…..You will generally be aware of the animal’s presence in the area; as the whales most likely to breach, such as humpbacks (or minkes), are quite visible on the surface as a result of their shallow dive sequences during which their robust backs and bushy “blows” will be fairly evident.  If you are close enough to the whale you will note certain diagnostic features such as the white bands on the pectoral fins of minke whales, or the long slender 12-15ft white pectoral fins of humpbacks, which wrap around their robust bodies as they twist while breaching. Whales may breach more than once in quick succession, which may contrast with basking sharks which may more typically breach just once.  That said, one of our observers off Slea Hd., Kerry has seen a basking shark breach six times in a row.  Finally, further re-sightings of the whale should be possible, as you know its location and it must re-surface to breath. If the scenario best reflects what you saw, then it is indeed more likely that what you saw was a whale, and not a basking shark.   

So, yes, basking sharks can and do breach, and this behaviour is likely to be more common than many would assume. Emmett Johnston of www.baskingshark.ie is of the opinion that breaching is associated with their mating.

Anyway, basking sharks are here, and in the coming weeks, numbers will hopefully build as warmer weather heats up the sea and enourages the growth of the zooplankton the sharks are feeding on.  Chose your weather carefully, as flat calm seas and overcast skies are perfect for spotting their dorsal and tail-fins. Make sure not to double count, as when feeding on the surface they will often show both fins at same time, and on occasion a 3rd feature may show if their snouts break the surface. Based on the flow of sightings reported to IWDG, we'd be of the opinion that the Northwest inshore waters of Sligo and Killala Bays are likely to represent your best chance of spotting this mighty grazer.....and please do report your sightings to us on www.iwdg.ie or to our colleagues at www.baskingshark.ie.

Pádraig Whooley, IWDG Sightings Co-ordinator