‘Like the flip of a switch, it’s gone’: has the ecosystem of the UK’s largest lake collapsed?

Declan Coney, a former eel fisher, knew there was something wrong when the famed swarms of Lough Neagh flies failed to materialise. In past years, they would appear around the Northern Irish lake in thick plumes and “wisps” – sometimes prompting mistaken alarm of a fire incident, Lough Shore residents say.

Clothes left out on a washing line “would be covered in them”, Coney says. So would any windshield on a vehicle travelling around the lough’s 90-mile shoreline. Conservationists marvelled at their courtship dances, hovering above treetops.

Last spring the flies never arrived. “This is the first year ever that, if you walked up to the Cross of Ardboe or the area around there, you’d find there’s no flies,” Coney says.

The flies were long considered a nuisance. Now, however, alarm is growing. “People have really been scared,” he says, by the rate of accelerated change to the lough’s ecology that their absence signals. “It’s just happened. Like the flip of a switch, it’s gone.”

“Lough Neagh fly” can refer to various non-biting midges, but these crucial insects support fish and wildfowl that are endemic to the lough system, as well as frogs and predatory insects. The loss of these keystone species, alongside sharp reductions of others, the spread of invasive species like zebra mussels, and a long-term deterioration in water quality, indicates deep trouble across the lough’s entire ecology. It also raises the prospect that this shallow body of water and its surrounding wetlands may have shifted beyond a state of decline into cascading ecosystem collapse.

Lough Neagh – the largest freshwater lake in the UK – supplies more than 40% of Northern Ireland’s drinking water, and hosts the largest wild eel fishery in Europe. It is considered a cultural and archaeological “jewel” that reaches “way back” into the very beginning of shared memory on the island.

Last summer, a vast “bloom” of blue-green algae – a thick, photosynthesising blanket that deprives the lake of oxygen, choking aquatic life – brought the lough’s accelerating biodiversity crisis into sharp focus. It prompted considerable public outcry and is expected to return in “more severe” form this coming summer.

The toxic algal growth – described by local people as appearing like something otherworldly due to its brilliant green or blue appearance – has since disappeared from the surface of the lough, but remains visibly suspended just underneath.

The problems have been exacerbated by the paralysis of Northern Ireland’s power-sharing institutions, which have been dormant for 40% of the period since they were formed by the Good Friday agreement, including almost all of the past two years. Members of the devolved assembly only began debating the management of the lough last week. As the politicians gathered, new reports emerged of a thick, pale scum appearing on the lough’s waterways.

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From the mouth of the River Blackwater, Ciarán Breen rows out on to Lough Neagh. Breen has spent about three decades working on this body of water. His vessel is a cot, a small wooden boat he helped to build by the shores of Maghery, a village near Portadown on the lough’s southern end.

Breen pauses to take stock of the losses he has witnessed since he began work here as a wildlife ranger in 1986.

“In the winter, we did an annual wildfowl count – a colleague and I did this particular section,” he says, gesturing towards an area of several square kilometres between Coney Island and Kells Point.

“We got about 50,000-60,000 diving ducks. So many that people – our bosses, I mean – came out of Belfast to take a look for themselves, since they didn’t believe us at first.”

These fleets of pochard, scaup and goldeneye made Lough Neagh an internationally significant site for overwintering birds in the 1980s. In the years since, their numbers have plummeted. A 2013 study found that the number of these winter migratory birds at the lough had dropped nearly 80% in a decade – from 100,000 to fewer than 21,000.

“We’re looking out there – at the same spot – now,” Breen says. “There’s a wee flock of coot and no ducks. None. So there’s been a catastrophic collapse in duck numbers from when I started.”

Overwintering whooper swans from Iceland used to arrive as December approached. “For many years, they would herald the winter coming in,” says Tom McElhone, who lives near a disused freshwater laboratory at Traád Point on the lough’s north-western shore – its last major research facility, which closed in the early 2000s.

“I remember lying in bed and hearing these swans calling out to each other, up and down the lough, having this magnificent conversation at all hours of the night. That’s all gone.”

Even when they move away from it, Lough Neagh courses through the veins of those like Coney, raised on its south-western shores, who have worked the water or resided within one of its many tight-knit local communities.

The 53-year-old believes, however, that many of the social ties and customs that helped fuse together these shoreline villages, parishes and townlands have unravelled during his lifetime, mirroring a progressive decline of the lough’s central fishing industry.

As the number of boats fishing the waters has dwindled – from more than 200 in the 1980s to a few dozen today – so too, he says, have the summer fairs and “lough shore tug of wars”, the ad-hoc music sessions, hyperlocal vernacular – even residents’ familiarity with the water body itself.

“The local knowledge is not there any more,” he says. “And that sense of togetherness along the lough shore is just gone.”

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Along the walls of the Toome Canal, at the north-western tip of Lough Neagh, chalk-like bright blue residue from the algal blooms was visible for weeks after the thick sludge of surface algae had disappeared from sight. Warning signs have remained in place at sites such as Ballyronan throughout the Christmas holidays and into early 2024.

The algal growths have robbed people not only of this year’s summer craic – families around the lough, say – but also of something calming, restorative, even “healing”.

And they have also prompted a belated “awakening” to the lough’s plight, in the words of the lough shore resident and former MP for Mid-Ulster, Bernadette McAliskey (nee Devlin).

She and other veteran civil rights leaders – who took up the cause of the area’s disfranchised fishers in the 1960s – have been speaking up for the lough once again.

Addressing a rain-drenched demonstration by the same canal in late November, just a stone’s throw from the eel fishery’s headquarters, McAliskey cited talks to bring the lough into a community co-operative trust nearly a decade ago. It was one of a number of lost opportunities for public ownership over the past 50 years.

“Our evidence was [that] people look after what belongs to them,” she said.

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Ownership of Lough Neagh has a long and contentious history. The aristocratic Shaftesbury family has claimed the lough’s bed, banks and soil since the 19th century, having been given the asset by the Chichester family, whose territorial claim dates back to the Plantation of Ulster in the early 1600s.

The lough’s fishing communities were once bound together by a history of struggle in defending public rights to fish the lough that, in the words of House of Lords judges at a key 1911 appeal case, had been exercised “from time immemorial”. But now, Coney says, many have become despondent due to mismanagement of the water body, and a “lack of industry support” or apparent outside interest.

Those who fish for the increasingly emaciated, scattered eels only managed three weeks last season, which would usually run from May to late October.

The lough’s ecological and economic decline is now playing out amid fragmented management structures, and a lack of key scientific data – ecological “baselines”.

Local communities fear that the lough may be sold on to a new private owner – a prospect the 12th Earl of Shaftesbury has not ruled out publicly. Among many, there is a profound lack of trust or confidence in management and governing bodies.

“The priority has to be sustaining the life of the lough,” McAliskey told the Toome rally. “Because if we sustain the life of Lough Neagh together, Lough Neagh will sustain the rest of us. So long as we work in harmony with her, there is a living [here] for everybody.

“This whole lough could be an income generator that keeps all of our young people from emigrating to the cities and emigrating out of the country. We could have a really good life around this lough, while supporting the rest of the ecology.”

But Breen, who has also worked in government, is less optimistic.

“They’re hoping this will blow over, now the algae’s disappeared from sight”, he says of decision-makers and government, “and that it’ll be back to business as usual.”