15 May 2025

The Arctic charr (Salvelinus alpinus) is a cold-water salmonid related to salmon and trout. Populations in England are near the southern extent of the natural species range, with all English populations being located in the Lake District (Figure 1). The species is declining globally due to a range of pressures including nutrient enrichment, acidification, land-use pressures, over-exploitation and the effects of non-native species and climate change.

Some Lake District populations seem to be faring better than others but the population in Windermere is particularly impacted by nutrient enrichment, invasive non-native species (e.g. roach) and the many impacts of climate change. The population in Windermere is one of the most complex in Britain, due to the existence of up to five different ‘races’ within the same lake. Races are separated by their timing of spawning in autumn (November) or spring (February–March), and their location within the lake (North and South Basins). The fifth potential race, now thought to be lost, was a river-running population that spawned in the River Brathay, which feeds the North Basin. Like other salmonids, Arctic charr need a coarse, stony substrate dominated by gravel, pebbles and cobbles in which to create their nests, known as redds. To survive their incubation period, fertilised eggs require very clean spawning sediments with low levels of organic matter. High temperatures and low dissolved oxygen concentrations can be lethal for salmonid eggs.

The Freshwater Biological Association has recently formed a partnership made up of fish biologists, ecologists, researchers and industry partners with the main focus of better understanding the pressures on the species and saving populations from extinction in England. The Lake District Charr Recovery and Management project (LD-CHARM) is funded by Natural England’s Species Recovery Programme and the Environment Agency, as well as by some of our private partners, to address important knowledge gaps, namely:

1. Are Arctic charr still using their historic spawning grounds in Windermere?
2. What is the condition of Windermere spawning grounds, and what are the major human pressures reducing their condition?
3. Do the different races within Windermere constitute genetically independent populations?
4. What is the genetic structure, differentiation and diversity of Arctic charr populations in the Lake District?

Answering these questions will help the FBA to design a conservation plan, prioritise restoration actions and identify further research needs for this species in England, whilst setting this information in the wider, national context.

LD-CHARM will have a busy year working to advance our understanding of the Arctic charr, one of the Lake District’s most enigmatic species, so keep up to date with the latest developments on the FBA website