A crayfish which populates Cumbria's rivers has been listed as endangered, sparking concern among conservationists.
Cumbria has Europe's only stronghold population of white-clawed crayfish.
It is now listed as "endangered" on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
South Cumbria Rivers Trust said the species was at risk from the American signal crayfish.
The American signal crayfish was introduced for food in the late 1970s and 1980s, and carries a plague which affects only the white-clawed species.
The white-claw crayfish's immune system does not recognise the fungus and it will spread unchallenged through their body, eventually killing it.
Paul Bradley who has been studying the native white-clawed crayfish and the plague for more than 10 years in the region, said: "Cumbria supports possibly the best white-clawed crayfish population in Europe.
"They are therefore very vulnerable to the plague and a single incident of the plague could devastate the Cumbrian population".
Bekka Close, co-ordinator of the Cumbria Freshwater Invasive Non-Native Species Initiative, advised fishermen to dry equipment to help stop the spread of the plague, as it can be transferred on anything that gets wet.