Common dolphins still bear the brunt of Spring strandings

5th Mar 2019

Up to today (5th March), IWDG have recorded 54 cetacean strandings in Ireland. Once again, common dolphins are by far the most frequently recorded species - 30 identifiable animals represent 56% of all species stranded. This has been the case in Ireland since 2011 with consistently high numbers of common dolphins washing ashore dead, especially during January, February and March.

Interestingly, numbers are down this year compared with 2018 - the year with the dubious privelege of highest annual total of cetaceans strandings on record in Ireland (272). By this time last year, we had already received 95 stranding records of which 60 (63%) were common dolphins. To put this in some perspective, we can look back to 2009 (a 'normal' pre 2011 year..) and between 1st January and 5th of March that year, IWDG recorded 26 strandings of which only 3 (12%) were common dolphins!

 

Common dolphin, Ventry, Co. Kerry 1 March 2019, Nick Massett

So, numbers of dead animals washing ashore are still very high compared to historical records but have fallen since last year, so this is good news maybe? Not necessarily. Strandings in January this year were down to 14 compared to 32 in 2018 and 27 in 2017. Strength and direction of prevailing winds appear to have quite an effect on whether dead floating animals wash ashore or not.

The early part this year was relatively calm and our normal south westerly winds were replaced by more south easterlies and interestingly, 8 common dolphins were washed ashore in Wexford, more than we would normally expect. The flip side to this is that any floating carcasses off the west coast (where most strandings are normally recorded) would be blown further offshore where they would eventually sink due to decomposition and predation.

Stranding recording is not an exact science with perhaps less than 10% of dead animals actually washing ashore and being recorded, but it does give an indication of trends and we can still see that strandings of common dolphins remain particularly high early in the year. Fortunately, a good proportion of dead common dolphins, striped dolphins and harbour porpoises were in reasonable condition and were retrieved by IWDG for post mortem examination at the Regional Vet Lab in Cork under a scheme funded by the Marine Institute and National Parks and Wildlife Service with a view to establishing cause of death in these species.

Mick O'Connell, Strandings Officer.

 

Cover Photo: Common dolphin, Tramore, Waterford, 18 February 2019, Trish Hogan

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