Country diary: The breathtaking sight of a tuna taking flight in British waters

Bluefin tuna … ‘Dark on top, with fins like daggers, its silver underside is lit up by the sun.’ Photograph: Ray Harrington/Devon Sea SafarisView image in fullscreenBluefin tuna … ‘Dark on top, with fins like daggers, its silver underside is lit up by the sun.’ Photograph: Ray Harrington/Devon Sea SafarisCountry diary: The breathtaking sight of a tuna taking flight in British waters South Hams, Devon: These are monstrous animals, growing to 3 metres and reaching 40mph, and I was lucky enough to see a pack in hunting mode

It is a perfect autumn day for a clifftop walk: sea and sky blend into a veil of baby blue, and the water is calm and dazzling. A motorboat unzips the ocean as we squint out over the bay.

My companion points to a dark line snaking along in the water. It seems to intensify for a moment, then erupts in a silver commotion. Through binoculars I can make out the frantic leaping of a shoal of eel-like fish. “Garfish,” he says. “Now just watch.”

Suddenly, the water erupts as a monster bursts into the air, scattering the garfish like sequins. Dark on top, with fins like daggers, its silver underside is lit up by the sun, massive as a billboard caught in headlights. It crashes down, swallowed up by its own whirlpool. Another leaps, and another. Tuna!

By the time I’ve remembered to breathe again, the surface of the water is still and twinkling once more, as if I’d hallucinated the whole thing. Atlantic bluefin tuna (Thunnus thynnus) have, as I’ve just found, made an astonishing return to British waters. And what astonishing animals they are – they can live up to 50 years, grow to 3 metres and reach speeds of more than 40mph. This apex predator hunts in packs, herding its prey to the surface. I’m glad I’m not a garfish.

View image in fullscreenAtlantic bluefin tuna off the Devon coast. Photograph: Ray Harrington/Devon Sea SafarisA common sight off England’s south coast until the 1950s, overfishing then pushed them almost to extinction here. In the early 2000s, strict regulations were introduced – and the results are clear to see. This shows “the power of effective management”, as Chris Graham of the Marine Conservation Society puts it.

But Chris also identifies the “background issue” of global warming, which is changing the migration patterns of tuna and their prey. Bluefin tuna need warm water and, after this year’s heatwaves, the Devon coast must be like heaven.

The multiple catastrophic effects of the climate crisis on ecosystems are … well, too horrific to look at head-on. So let’s focus, if only for today, on this astonishing good news story. In 2021, Atlantic bluefin tuna were reclassified on the IUCN red list from “critically endangered” to “least concern”. It’s a giant leap.