Scotland failing to protect Ice Age fish, the Arctic Charr

“I feel,” he said, “I have been stonewalled by every cabinet secretary for environment from the days of Roseanna Cunningham to Lorna Slater who has palmed me off. But the problem isn’t really with the politicians. They are non-specialist themselves. It’s the inertia of the bureaucrats.”

Arctic charr, like brown trout (another species Greer says is under threat), are part of the Salmoniae family and related to the iconic salmon whose decline has been far more publicised.

Often the charr are described as like the Galapagos finches, because like the birds Charles Darwin came across in those Ecuadorian isles, different populations, cut off from each other in their own lochs, have developed different features, their own local form.

“If you can imagine,” said Mr Greer, “a part of the Cairngorms the same area as these lochs, and it had four or five different types of Ptarmigan there would be huge efforts to protect it. It’s just that fish don’t have a good public profile. They’re cold, wet and slimy. They’re not cuddly and furry. And they don’t turn up at Chris Packham’s bird table.”

Arctic charr are predominantly found in deep loch systems in Scotland, sometimes at depths of 200-300ft. Till Greer started looking for them, he recalled, “We didn’t even know where there because it was unexplored. “

Mr Greer has been working on the fish since the age of 23 when he was working in the government's freshwater fisheries laboratory in Pitlochry. “I realised," he said, "there was this fish called Arctic charr that we didn’t know very much. I even learned Norwegian so I could access their literature.”

The freshwater ecologist studied the fish in Norway and came back and started “dipping nets” into lochs to see what charr were there. He recalled: “The more I looked at lochs the more I realised that we’ve got hundreds of populations. We’ve got more populations of Arctic charr than anywhere in Europe outside the Scandinavian countries. Instead of finding they were very rare, I realised they were actually very common.

“I now look at Scotland as just a big island off the coast of Scandinavia. You look at that and you realise why there are so many Arctic charr. It's because Scotland is a sub-Arctic country.”

The fish biologist highlighted sites where either charr or brown trout are under threat. These are  Loch Rannoch (where the threat is from roach and rudd), Loch Earn (where the threat is from non-native vendance) Loch Laidon (where brown trout are threatened by non-native pike) and Loch Insh (which has seen explosive expansion of non-native perch and roach).

He sees only two possible answers to what he describes as an existential threat. “A, the use of the piscicide rotenone; and B, translocation to a receptor loch where the existential threats do not exist.”

The source, he said, of the problem at Loch Rannoch is that roach and rudd that were introduced to Loch Monaghan and Loch Finnart are filtering down and there is a danger that these fish compete with the plankton-feeding charr, which will be threatened or wiped out. An extraordinary three-species ‘assemblage’ there, Greer said, is under threat. The dangers are further  enhanced by climate change since the invasive species are less vulnerable to warming waters.

Mr Greer compared the presence of the invasive fish to “someone putting grey squirrels into Rothiemurchus”.

“Can you imagine that? Or someone put mink at the top of the Cairngorms and they’ve eaten all the Ptarmigan. Another analogy is that it’s like finding the Black Wood of Rannoch is now full of Sitka spruce, Japanese knotweed and rhododendron. But it would actually be easier to remove.”

The charr in Loch Rannoch, he observed, are even more ancient than the native pine trees - and have been in those waters for 12-15000 years.

Mr Greer's proposed solution for Loch Rannoch is the application of rotenone to the manmade lochs Finnart and Monaghan.

Brown trout

However, Dr Katherine Leys, NatureScot’s Head of Biodiversity and Geodiversity, said: “One of the management options Mr Greer refers to in order to reduce the threat to Arctic charr from non-native species is the use of the broad-spectrum biocide rotenone, which will kill both invertebrates and fish. 

"The Scottish Environment Protection Agency is the public agency responsible for non-native species and authorising the use of biocides in the freshwater environment, and as such, would need to consider this proposal. However, it is our view that the use of rotenone is unlikely to be compatible with the protected features of the lochs.

"A natural pyrethrum-based biocide called Pyeblast has been used to control signal crayfish in Scotland, but only in a few small waterbodies which were not connected to freshwater systems."

A spokesperson from the Scottish Environment Protection Agency (SEPA) said: “SEPA are aware of the issue of non-native fish in Lochs Monaghan and Finnart. To confirm the distribution of non-native fish in these lochs and Loch Rannoch, SEPA collected samples in 2023 for environmental DNA analysis. The results confirmed the presence of roach, rudd and crucian carp in Loch Monaghan, and the latter two species in Loch Finnart. There was no indication of the presence of any of these species in Loch Rannoch.

“SEPA are actively collaborating with NatureScot and the Rannoch and District Angling Club to assess potential options for management of the non-native fish in Lochs Monaghan and Finnart, taking into account the conservation designations of species and habitats in the lochs.”

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Meanwhile, at Loch Insh, said Mr Greer,  there are also threats to the charr because of the introduction of locally non-native perch and roach. Attempts are being made by the Cairngorm National Park Authority to deal with the problem, and Greer praised these. But, he said, “a translocation of the species to a different loch where the threats are not present” is vital.

NatureScot is the licensing authority for conservation translocations and Dr Leys said:  "We can consider this option where there is shown to be a significant risk to a species of conservation concern, a suitable site can be located which can support the species over the long-term and there is no risk to native biodiversity."

“We’ve ruined the terrestrial environment,” Mr Greer said, “but, in the deep-water lochs, we’ve still got the original Ice Age associations there. There’s something special left there that has been relatively untouched for 15,000 years and now we’re in the process of screwing that up as well.”

“We talk about the future of Scotland's biodiversity. These charr are original biodiversity. They were swimming about when the mammoths and the musk ox and the reindeer and all the rest were roaming about. And they have been lying there up until now totally unexploited and unaffected. But now it’s beginning to happen. And it’s beginning to happen in full knowledge of what we’ve done on land.

"Here we are trying to save the wildcat, but  we’ve got the original in the lochs and we’re doing little to protect it.”

A Scottish Government spokesperson said: “Scotland’s native biodiversity is vitally important to our freshwater lochs and rivers, with Arctic charr recognised as a species of significant conservation value, and Loch Rannoch, Loch Tummel and Loch Laidon internationally renowned for their Atlantic salmon and lamprey, as well as their water quality.

“Legislation came into force in 2008 to regulate the introduction or stocking of all species of freshwater fish to protect native biodiversity and applies to all stocking of freshwater fish, including rudd, roach and perch. The introduction of any fish species into freshwaters requires a licence from the Scottish Government Marine Directorate, or NatureScot if it is a water body outside where it would naturally be found. Anyone who deliberately introduces a species of fish into Scottish freshwaters without the appropriate licence is guilty of an offence.

“The recent publication of the draft Scottish Biodiversity Strategy outlines that tackling the causes of the decline of freshwater fish is a priority for NatureScot and our partners within the Scottish Government as well as the wild fisheries sector. Landscape-scale action to protect and improve the condition of freshwater habitats is key to mitigating the climate emergency and ensuring the continued survival of less well-known species such as Arctic charr, European whitefish and Vendace. This is why we are working with partners to ensure that water bodies supporting these valuable parts of our freshwater biodiversity are protected.”