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White-beaked dolphin washed ashore

16 June 2013

…Old news now perhaps, but this is really the first chance I’ve had to post to the diary so I thought I’d write a few words anyway... 

In May (see, old news!) a cetacean was discovered washed up on the beach at Village Bay.   Over the next few weeks it was pecked at by birds and by the time I arrived on island it was thoroughly stinking and looking quite a sorry sight.   Despite its poor condition, it was easy enough to identify as a white-beaked dolphin (Lagenorhynchus albirostris) due to the tall, curved, dark dorsal fin, short rounded beak, thick tail, white belly and pale markings on the flanks.   

White-beaked dolphin (stock image, HWDT)
Although this species is the most frequently sighted dolphin species around Scotland, it is not commonly recorded in the waters surrounding St Kilda.  Our reports indicate that a group of four animals were noted on one day in June and July 2006 and a group of six were seen breaching near Boreray in July 2010.   However, it is quite likely that, at a distance, this species could be mistaken for its close relative the Atlantic white-sided dolphin (Lagenorhynchus acutus) as both species are fast, powerful and active swimmers that usually occur in groups

 

I reported the stranded dolphin to the Hebridean Whale and Dolphin Trust and the Scottish Marine Animal Stranding Scheme (SMASS).  Unfortunately, the carcass was a little too decomposed to determine the cause of death so the reason why this dolphin ended up on our shore will remain a mystery. If St Kilda was less ‘remote’ then a scientist from SMASS may have visited to gather information on the dolphins foraging habits (by analysing stomach contents), age (by taking a cross section of a tooth and counting the number of layers, similar to ageing a tree!), where it may have travelled (by using a technique called stable isotope analysis) and if it was contaminated with any pollutants (by analysing a sample of fat as chemicals accumulate here).  This time, samples weren't taken but I was at least able to pass on detailed measurements that will be logged in the national database.

It’s not often I get the chance to be so close to a dolphin so I took some photographs when I was measuring the animal.  The images aren't too bad but if you’re at all squeamish then it might be best to avoid looking at the montage below!! White-beaked dolphin montage of images

Gina



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Won't need the ID book for this....