THEY love scallops in Oban. “We can’t get enough of them to meet demand,” smiles Carol Watt, whose family firm has been selling fish in the Argyll port for more than a century.  As a queue of masked shoppers forms outside her little mustard-yellow hut, Watt describes how she likes to cook the mollusc, pan-seared and served with pancetta, Italian bacon.

Wearing an apron emblazoned with a multi-species shoal of fish, Watt beams with delight as she shows off a tray of shelled scallops, palm-sized pale fleshy discs still attached to the blazing red roe some consumers find too pungent.

The shellfish, sometimes called plain “clams” in Scots, never used to this popular.  Just sixty tonnes of the species were landed at Scottish ports in 1960. In 2019 the equivalent figure topped 15,000 tonnes, down 2% from 2018 but still worth nearly £36m.

The boom, however, has sparked a sometimes bitter clash between environmentalists and the fishing industry over how scallops, which grow on the seabed, are harvested.  Some “clams” are sustainably lifted out of the sea by divers who charge a premium to do so.  Most, however, are dredged, scraped off the ocean floor by bottom-trawlers.  Diver-fishermen and campaigners say dredgers are effectively ploughing through delicate marine environments to create a scallop monoculture off the Scottish coast.

Trawlers counter that they too fish sustainably; that they stay clear of environmentally sensitive areas; and that seabeds recover.  In Oban this is no academic dispute. Watt’s scallops are dredged. So are those sold at another fish hut on the harbour, a green one whose sign grandly declares Oban the “seafood capital of Scotland”.  Nearly half of Scotland’s shellfish comes from the west coast. So here divers and dredgers live and work cheek by jowl. But not always easily.  Divers have been recording damage they say is done by industrial scalloping.

There were 48 reports of suspected illegal dredging - when trawlers enter marine protected areas or MPAs, the tiny proportion of Scotland’s seas set aside for nature -  between the summer of 2019 and 2020. Most reports, however, are almost impossible to substantiate or, for that matter, unsubstantiate. What happens at sea is "yonder awa", out of sight.  Divers and environmentalists believe Scotland’s fisheries watchdog, Marine Scotland, is too lax, too close to industry. Dredgers think the regulator is too tough, its SNP masters too close to the Greens.

Stef Cooper is a diver who has blown the whistle on dredging damage, helping to document the tell-tale tramline tracks left after such fishing.

He dives from a boat called the Compass Rose, now berthed at Oban harbour.  The 39-year-old can take home £300 a day - albeit a long-long day of up to 13 hours - if he picks 100 kilos of scallops, enough to fill his big green net - the size of a potato sack, twice over.

“It is like being a hunter-gatherer,” says Cooper, echoing a term also used by trawlermen.

Two boats down the quay from the Compass Rose is a scalloper, a dredger. What does Cooper think of what it does?

“I have mixed feelings,” he replies. “It is a bunch of guys trying to earn a crust. And nobody can have anything against anybody doing that.

“But when they are out there just bulldozing the seabed,” he trails off, takes a deep, snorkellers’ breath and adds: “If this was a national park being bulldozed by a private company there would be outrage. But nobody sees it: it is invisible.”

Cooper has been diving for scallops for a decade. Off Orkney, Mull and Oban. “It is heartbreaking, he says describing the seabed after dredging. “It is like the difference between being in a wild wood or in a ploughed field.”  How are relations between dredgers and their critics? “There is no RAC or AA at sea,” Cooper says. “So we rely on each other.”

However, reporting alleged wrongdoing has make things awkward.“It is always going to cause issues because it is seen as a betrayal of the fellowship of the sea,” says Cooper.  “There isn’t any enforcement, it is only on paper. “Even when they have been caught within the MPAs, they get a parking ticket level of fine.” Cooper’s view is backed by sustainable seafood charity Open Seas. It wants to flip the balance of sea use. Instead of roughly a twentieth of inshore Scotland waters being protected, they think most should be, with areas set aside for bottom-trawling if they are deemed resilient.

Dredging was banned within three miles of the Scottish coast from 1889 to 1984.  At Oban Harbour David Fraser - nicknamed Toastie thanks to a long-lost holiday tan -  scoffs at the very idea of going back to those days. He dredges for prawns, not scallops, but he has done his time fishing for the latter species too. Now 61, has been going to sea for 35 years.  “I have fished right around Britain,” he says as he loads crates on to his 45-year-old 11.5m prawn boat, the snub-nosed, wooden-hulled Girl Errin. “And I have always done so sustainably or I’d not have a business.”

Fraser has stayed in port because of the weather - it is a dreich December morning. He normally supplies local businesses like Carol Watt’s fish shop and - as he demonstrates with a sweep of his arm - the upmarket Eu-usk seafood restaurant across the harbour.

“These guys can afford to sit and tap away on their keyboards while I am trying to make money in a legal and sustainable way,” Fraser says.

“There are people from towns and cities who know zero about this environment telling me how it should be run. All they do is tap tap tap.”

Saying he is “very angry”, but rarely resting what looks like a permanently-fixed friendly grin, Fraser disputes that bottom-trawling harms sensitive features. Why? Because dredgers do not, he says, risk their valuable gear by dragging it over anything other than sandy flat beds of scallops.

“What the general public don’t realise about the seabed is that it has valleys and troughs and deepwater,” he explains. “So scallopers fish in a tiny percentage of the seabed.

“You are not going to tow through the kelp forest, the kelp blocks up the gear. We don’t want to drag our gear over a rock - it breaks.”

Fraser used to dive. Like Cooper, he has seen the bottom after dredging. But he tells a different story.  “It is not a sterile desert: it is all life,” he says. “If you drag over a sandy bank; it will have an impact but this will disappear in a couple of weeks. The scallops come back in the same places every year.  “That, in my book, makes it sustainable.”

The charge from environmentalists is that the dredging is creating spaces for scallops - but not other species. Nick Underdown speaks for Open Seas - one of the people Fraser accuses of “tap-tap-taping”. He thinks the damage being done to the seabed is being ‘normalised” and that this is bad for the long-term future of fishing.

“Many within the dredge fleet have fished this way for decades now,” he says. “The changes over this time are undeniable –  fish stocks are not recovering, and government scientists are confirming that seabed habitats are still in decline. These are not just pretty habitats, they are fish nursery grounds and a public asset.  “Much of our seabed could be teeming with life if left alone, rather than dredged as a monoculture for scallops. It’s a difficult thing to say – but dredging is undermining the viability of other fisheries, other potentially more sustainable livelihoods.”

Open Seas has accused vessels belonging to large commercial operators of “stealing” in to MPAs. This stance infuriates John “The Dredge” MacAlister, who talks on the species for the Scottish White Fish Producers Association and owns and runs one of the country’s biggest fleets of scallopers.

Speaking on a gangway outside his Oban base overlooking the harbour, The Dredge lets rip at Open Seas. “They put stuff to the media with no sound backing whatsoever,” he says. “They are putting our businesses on the line with unfair allegations and unfair research.”

As his gold medallion, in the shape of a ship’s wheel, glints in the midwinter sun, MacAlister denies any of his skippers have ever been in any trouble with Marine Scotland.“We are not causing the damage they claim,” he says. “That would be against my interest.  “We are seeing better signs this year than we have seen in a decade. More young scallops.”

Nobody in Scotland has scalloped more than MacAlister, who skippered his first boat at 17. He has been in the trade for 50 years  - “five-oh” he clarifies - and insists the same underwater features that were there when he started are still there now. Campaigners are not convinced he is right. The clam wars are not over.