Record dol­phin num­bers viewed on West Coast

The Oban Times - - OUTDOORS -

RECORD num­bers of three dol­phin species off Scot­land’s West Coast were recorded by Mull-based con­ser­va­tion char­ity the He­bridean Whale and Dol­phin Trust in its ma­rine re­search ex­pe­di­tions in 2016.

From the trust’s spe­cialised re­search yacht Sil­urian, vol­un­teers and sci­en­tists recorded 2,303 in­di­vid­ual com­mon dol­phins, 42 bot­tlenose dol­phins and 94 Risso’s dol­phins – the fig­ures for all three species be­ing the high­est ever recorded in its an­nual sur­vey sea­sons.

Av­er­age an­nual fig­ures doc­u­mented over the pre­vi­ous 14 years were 463 in­di­vid­ual com­mon dol­phins, 14 bot­tlenose dol­phins and 12 Risso’s dol­phins.

For com­mon dol­phins, these records range from no in­di­vid­u­als en­coun­tered in a cou­ple of the ear­lier field sea­sons to 1,862 dur­ing the 2007 sea­son.

Dr Lauren Hartny-Mills, science of­fi­cer of He­bridean Whale and Dol­phin Trust, said: ‘The rea­sons for the high num­ber of sight­ings of these charis­matic dol­phin species – and the broader ef­fects on the ma­rine en­vi­ron­ment and other species – re­main un­clear.

‘But the in­trigu­ing find­ings high­light the im­por­tance of on-go­ing mon­i­tor­ing and re­search – to strengthen our un­der­stand­ing of what is tak­ing place in He­bridean wa­ters, and to en­sure well-in­formed con­ser­va­tion ac­tion.’

The lat­est find­ings were made in a re­search sea­son last­ing from May to Oc­to­ber 2016, as part of the trust’s unique longterm ci­ti­zen science pro­ject mon­i­tor­ing whales, dol­phins and por­poises – col­lec­tively known as cetaceans – as well as bask­ing sharks in the He­brides.

These an­nual re­search sur­veys de­pend on pay­ing vol­un­teers, with 71 wel­comed aboard in 2016 – work­ing with ma­rine sci­en­tists on vis­ual sur­veys and acous­tic mon­i­tor­ing with un­der­wa­ter mi­cro­phones or hy­drophones, and iden­ti­fy­ing in­di­vid­ual cetaceans through photography.

The Isle of Mull-based or­gan­i­sa­tion now holds data from more than 95,000km of sur­vey ef­fort. It aims to pass the 100,000km mile­stone dur­ing 2017, and it is cur­rently re­cruit­ing vol­un­teers to sup­port this by work­ing as ci­ti­zen sci­en­tists on­board Sil­urian for pe­ri­ods of al­most two weeks from April to Septem­ber.

Alison Lo­max, di­rec­tor of He­bridean Whale and Dol­phin Trust, said: ‘ The im­pres­sive range of species doc­u­mented in our at-sea sur­veys last year is a pow­er­ful re­minder that Scot­land’s West Coast ocean en­vi­ron­ment is home to re­mark­able ma­rine life. Longterm sci­en­tific stud­ies of this glob­ally-im­por­tant habi­tat and its in­hab­i­tants are cru­cial if we are to en­sure a se­cure fu­ture for the He­brides’ spec­tac­u­lar cetaceans.’

Dur­ing 2016, Sil­urian – pre­vi­ously used in film­ing of the BBC’s The Blue Planet se­ries – cov­ered more than 5,000 nau­ti­cal miles, com­pared to an av­er­age of al­most 4,000 miles an­nu­ally over the pre­vi­ous 14 years. Its crew doc­u­mented more than 1,300 cetaceans and bask­ing sharks, and recorded al­most 700 hours of un­der­wa­ter de­tec­tions of cetaceans us­ing spe­cial­ist lis­ten­ing equip­ment.

No­table high­lights in­cluded a won­der­ful en­counter with a hump­back whale in the north­ern Minch – an hour was spent with the mas­sive crea­ture lunge feed­ing, tail slap­ping and swim­ming un­der Sil­urian, along­side a large group of com­mon dol­phins.

Western Scot­land’s seas are among Europe’s most im­por­tant cetacean habi­tats. With a long, com­plex coast­line, strong ocean currents and a va­ri­ety of habi­tats, the He­brides is one of the UK’s most bi­o­log­i­cally pro­duc­tive ar­eas. So far 24 of the world’s es­ti­mated 92 cetacean species have been recorded in the re­gion – many be­ing na­tional and in­ter­na­tional con­ser­va­tion pri­or­ity species.

Yet ma­rine ecosys­tems are frag­ile, and cetaceans face in­creas­ing stress from hu­man ac­tiv­i­ties – in­clud­ing cli­mate change, en­tan­gle­ment, pol­lu­tion, un­der­wa­ter noise and habi­tat degra­da­tion.

The HWDT on their boat Sil­urian with Com­mon Dol­phins swim­ming along­side.

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