Fast and furious, they are regarded as the ‘Ferraris of the seas’ - lethal hunters, highly prized by big game anglers and craved by Japanese diners.

For years, Atlantic bluefin tuna were a rare sight in Scottish waters, with their numbers depleted as their prime source of food – herring and mackerel – landed instead on the nation’s dining tables.

So, when skipper Angus Campbell’s fishing boat Aqua SY 210 pulled up alongside the quay at Stornoway a few weeks ago, the whopping bluefin tuna his crew had landed – 10ft long and weighing 164kg - strung up for curious locals to see, there was more than a little interest.

“It was definitely very exciting,” says Mr Campbell, who has been fishing the waters off the Isle of Harris since he was just 15 years old.

Read more: Hive mind: David Beckham's a fan, now meet the Scots beekeepers buzzing for bees

“It took around 45 minutes to get that fish, so there’s a definite buzz for the guys who were fishing.”

It was Scotland’s first commercially caught Atlantic bluefin tuna for decades. Since then, Campbell, who has the country’s only commercial licence which allows him to catch 3.9 tonnes per season, has hauled in a second equally impressive 160kg tuna.

And although neither hit the heady heights of the astonishing £2.5 million fetched by one Atlantic bluefin tuna that sold in Japan in 2019 – Campbell’s haul was closer to £15 per kilo, with one heading to Islander Shellfish in Stornoway, the second to a fishmonger in Edinburgh – they have opened the door to what could be the Hebrides’ next big thing.

For having hunted bluefin tuna to almost extinction in the Pacific, Japanese markets are now increasingly turning their attention to revived stocks of their Atlantic cousins to feed their expensive appetites.

The Herald:

Japanese and global demand for sushi, sashimi and tuna steak has already fuelled a booming Spanish farmed bluefin tuna market. In Mediterranean waters, the fish are herded in nets in a method called purse-seine fishing, to be kept in open water before being despatched using the traditional Japanese ‘ikejime’ method - with a spike in the hindbrain intended to prevent stress and lactic acid which can affect the meat.

Outer Hebridean line-caught tuna, on a smaller ‘artisan’ scale and considered far more sustainable, however, is likely to be regarded as a far superior – and therefore more expensive - product.

Grant Fulton, who works for community company Harris Development Ltd and is also a Western Isles councillor for Harris and South Lochs, believes there is huge potential to grow a new ‘silver darlings’ fishing sector.

“We’re on a learning curve at the moment,” he points out. “But in five years’ time I’d hope to see four or five commercial vessels out here fishing and landing product to be processed on Harris, using the Isle of Harris brand that’s already associated with gin, whisky and tweed.

Read more: Green hydrogen fears: 'We feel we’re being used as guinea pigs'

“We are now looking at how best to process the fish and the possibility of smoking some of it; making a nice, artisanal product and one which people do not expect to see in the Hebrides.”

It has already taken years of careful planning to reach this stage: The Outer Hebrides Regional Inshore Fisheries Group became involved in exploring the potential of a rod and line blue fin tuna fishery nearly 10 years ago.

In 2014, a tagging programme was launched with Mr Campbell at the forefront; so far he estimates he has invested around £30,000 in equipment, crew and other resources.

The programme has helped identify patterns of behaviour: the bluefin tuna which arrive off the Hebrides have been found to be larger and stronger than elsewhere in UK waters.

The Herald:

While it also revealed the distances a single fish might over: one was found 200 miles off the south-west of Ireland, another in the Azores and the third in the Bay of Biscay.

The trials, involving several island vessels and others in England, led to the UK Government receiving the go-ahead by the International Commission for the Conservation of Atlantic Tunas to trial a small-scale commercial fishery, with a 39 tonnes quota split between ten licences around the UK.

However, crucial to developing the new sector in the Hebrides is understanding how best to handle the newly-caught fish in a way that will gain the most value, adds Grant.

To help, they are now looking across the Atlantic, to Boston, where the bluefin tuna fishing sector is both a commercial success story and a major tourism draw for ‘big game anglers’.

Read more: Ice station rebuild: the Scot on a mission to repair an Antarctic wartime base

“We are looking to replicate the kind of stuff that’s happening in Boston, where its artisanal rod and line fishing,” he says.

“The fish is then handled very carefully, and despatched when on boat.

“Handling is a priority when getting with bluefin tuna, as it’s a high value fish.”

Iain Kennedy, Economic Development Officer at Western Isles Council, says there is now a “real opportunity” to build a new fishery sector around tuna.

The Herald:

“Atlantic bluefin tuna are an iconic sporting fish, growing to over 1,500lb and with great strength, speed and stamina; they are one of the most sought-after gamefish on the planet, second only perhaps to blue marlin.

“Studies show that its economic value can be six times per tonne that of a traditional commercial fishery.

“We have seen numbers recover sharply from danger levels 15 years ago, and in the Outer Hebrides, these unique fish are now appearing in unprecedented numbers.

“There now exists a real opportunity to establish a world-class, sustainable, live-release fishery in our waters alongside a carefully managed commercial fishery.”

Read more: Meet the bravehearts breathing new life into crumbling castles

He says tourism and scientific research offer extra opportunities.   “Until the 1950s the UK had a thriving and highly valuable recreational bluefin tuna fishery operating mainly out of Scarborough.

“The collapse of the herring stocks saw the tuna fishery collapse and British big game anglers resorted to spending thousands of pounds pursuing these magnificent fish overseas.

“There is already a well-established skate fishery out of Oban where many recreational anglers travel from far afield to catch and release large skate.

“We must seize this opportunity.”

The Herald:

While the International Commission for the Conservation of Atlantic Tunas (ICCAT) says careful management of catch-size limits and catch reductions has contributed to “a rapid increase in the abundance of the stock” of bluefin tuna with numbers predicted to continue to increase, there is some caution from some quarters.

The Marine Conservation Society warns it’s not yet clear if populations have reached sustainable levels that can withstand increases in commercial fishing pressure.

And it has suggested the introduction of tuna fisheries may cause the UK’s stocks to be exploited too quickly, especially if management is deemed insufficient to avoid a free for all at sea.

Dr Kenneth Bodles, Head of Fisheries and Aquaculture at the Marine Conservation Society, said: “Bluefin tunas come back is a clear reminder that when we treat our seas right, species can stage a remarkable return.

Read more: Back on top – How slate from a west coast island is about to make a bold return

“As we witness this resurgence, it's crucial that we proceed with utmost care, adopting a management strategy that honours the fragile balance of our seas and respects this iconic species.

“We've seen the dire consequences of overfishing, and we must tread carefully to secure a future where our seas thrive for generations to come."

Meanwhile, for Angus, the drama of the chase and catch is a change from his other job: he runs day trips to St Kilda, taking summer tourists to see the abandoned township.

He is guarded when it comes to predicting how big and fast the sector might grow. “It's a brand spanking new fishing sector for the UK, and we have to take time to plan how to keep the quality in the fish,” he says.

Read more: How the Queen of the Clyde could become a US national monument

“The fish generates so much heat that when you have caught them, you have to cool them down very quickly. If you don’t, it spoils the meat.

“It takes quite a bit to do that properly.”

And although the rewards for high quality bluefin tuna in some markets are impressive, he doesn’t expect it to spark a dash among his fellow fishermen to take on tuna fishing.

“Fortunately, I have a tourism business that allows me to fish for tuna. But not everyone is going to jump on board – I can't see a huge number of boats doing it,” he adds.

 “You have to be really into fishing and have the spare time to do it.”