THE decline of a fish species that has been in Windermere since the last ice age has gone 'unnoticed' by the public, scientists say.

The lake is home to one of England's few Arctic charr populations, a cold fish normally found in sub-Arctic regions. They were trapped when the glaciers retreated from the area around 12,000 years ago. 

Windermere represents the southern edge of the species' habitat niche so it is the least resilient salmonid to warming lake waters due to climate change. 

There used to be a population of Arctic charr in Windermere that were river-spawning but the species is now contained to four groups in the north and south basins which spawn in either the spring or autumn. 

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According to the Freshwater Biological Association, the populations of charr in both basins have declined in the last two decades, largely from warmer lake waters which hold less oxygen, eutrophication from agricultural and wastewater pollution and the introduction of invasive species such as roach. 

The scientists say there is a 'lack of evidence' to drive decision and conservation actions. 

Simon Johnson, executive director of the association, said: "The decline of the Arctic Charr on Windermere has gone largely unnoticed by the public. Arctic charr are truly unique and are of global ecological and cultural significance. We must not be the generation that allows the charr to be lost forever from Windermere. 

"It’s time for a wake-up call; Windermere without Arctic charr should be seen as no different to a Lake District woodland without red squirrels or songbirds." 

Mr Johnson's association is starting a research and species recovery programme.

Last week, the biological association started their Arctic Charr hydroacoustic and eDNA sampling project in Windermere. 

The project is a consortium led by the Freshwater Biological Association involving Echoview, Blueprint Subsea, UK Centre for Ecology and Hydrology, University of Hull, Colin Bean - honorary professor at the University of Glasgow, University of Highlands and Islands, Institute of Fisheries Management, Lake District National Park Authority, Westmorland and Furness Council and the Environment Agency.