The return of bluefin tuna to Lyme Bay

“The best thing to look for if you want to spot tuna is a feeding frenzy.”

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In the last couple of weeks, there have been several sightings of tuna off the East Devon coast:

Whopping seven foot long bluefin tuna found off Devon – Devon Live

VIDEO: Coastguard called after huge TUNA swims into Exmouth waters | eastdevonnews.co.uk

Terrifying video shows paddle boarders being stalked by 10ft tuna fish on Devon coast – Devon Live

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And this is happening all along the south-west coast:

Lone kayaker spots huge shoal of tuna off Plymouth coast – Plymouth Live

Experts explain the summer’s surge in dolphins, porpoises, tuna and whales off Cornwall – Cornwall Live

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We have our own ‘expert’, who writes this week’s piece for the Herald – and is republished with permission:

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Sid Valley Biodiversity Group report: bluefin tuna seen in local waters

In this week’s report by the Sid Valley Biodiversity Group, publicity officer Charles Sinclair looks at the return of bluefin tuna to local waters.

Would anyone believe me if I said while I was canoeing for mackerel, I saw a tuna jumping in Lyme Bay? I find it hard to believe myself but it was very distinctive.

It happened twice. They were 100 metres away and it had me questioning what I saw, but their shape is so familiar. That was early one evening two weeks ago and since then the local press has reported sightings of tuna in Exmouth, so I don’t feel so daft.

Apparently UK sightings of bluefin tuna have been on the increase since 2012, with one fisherman in Falmouth reporting 45 sightings in 2018. The University of Exeter is involved in a study of tuna to try and understand their movements and distribution.

The evidence is clearly indicating a return of tuna to UK waters. They were once quite common here, hence the foundation of the British Tunny Club in 1931. Then 1940 saw the beginning of the decline in numbers in UK waters and by 1990 they were all but gone. 

So why are they back? Climate change is playing a part but the greatest influence is as a result of the Atlantic Multidecadal Oscillation. This is a swing in the currents in the Atlantic that bring warmer waters to our shores about every 60 years and we are about 20 years into the warmer cycle. The tuna are moving up from the Mediterranean and are being found in increasing numbers in the North Atlantic. They are a globally endangered species; the fact that they are now more common in our waters is not necessarily an indication of their numbers increasing.

What to look out for?

Maybe the best thing to look for if you want to spot tuna is a feeding frenzy. These are large circular areas of splashing water often with seabirds diving into the sea amongst the foaming waves. Otherwise, look out to sea for tuna jumping, their bubble-like body and fine tail make them easily recognisable.

The Sid Valley Biodiversity group would be very interested in any of your wildlife sightings, please email sidvalleybiodiversity@yahoo.com

Sid Valley Biodiversity Group report: bluefin tuna in local waters | Sidmouth Herald

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With more from local bluefin tuna projects:

Scientists at Sea Podcast – Atlantic Bluefin Tuna in the UK, with Tom Horton | Exeter Marine

News | thunnusuk

Marine and citizen scientists take to the seas to help secure a future for Atlantic Bluefin Tuna in UK waters – GOV.UK

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photo: Roter Thun, Bluefin Tuna (Thunnus thynnus) in Thunfischmas… | Flickr

   
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