Signal Crayfish found in the Derwent Catchment

Signal Crayfish found in the Derwent Catchment!! A member of the public has reported to the Environment Agency in Penrith seeing a crayfish in the St Johns Beck (Derwent Catchment) near Threlkeld. No crayfish (native or non-native) were previously known to occur in this catchment. Environment Agency staff from fisheries and FRB (Fisheries, Recreation and Biodiversity) have confirmed that non-native signal crayfish are present. Over thirty individuals have been recovered so far and it is confirmed that the population occupies at least 600m of St Johns Beck which is an important salmon spawning area. Further investigations are ongoing into the extent of the infestation and the source. This is the first time signal crayfish have been recorded in Cumbria and anyone who thinks they may have seen a crayfish in any of the tributaries of the River Derwent is urged to contact the Environment Agency immediately (0800 807060). Cumbrian rivers and becks support some of the last remaining populations of the native white clawed crayfish. Crayfish plague (caused by the fungus Aphanomyces astaci) has caused drastic losses of native crayfish in rivers in England. It is believed that this disease was introduced and is spread by the most frequently farmed species, the signal crayfish a carrier of the disease. Crayfish plague is spread by spores that are specific to crayfish but can be transferred between rivers not only by crayfish but also by fish, water, mud or equipment that has been in water where signals crayfish are present Preventing the spread of crayfish plague. As the spores remain viable only when damp, complete drying of equipment that has been in contact with water or sediments is an effective way of killing them. (This is probably the easiest and best way to help / prevent spread of crayfish plague – wash boats with tap water and allow to completely dry out (UV kills plague spores). Also please consider the order of rivers paddled. Please paddle the Derwent Catchment rivers last (Eden, Leven and Kent rivers first) and then wash all kit thoroughly.) Spores can also be killed by Iodine-based (iodophors) disinfectants. Disinfection of Equipment and Tackle. Typical iodophor products are Wescodyne/Iosan CCT and FAM 30/Iofarm, generally available from farm or dairy suppliers. Label information and manufacturers instructions should always be adhered to, but as a broad guide, Wescodyne/Iosan CCT should be diluted 1.5 parts in 100 with water, and FAM 30/Iofarm 1 part in 100 with water. Disinfection is best achieved by first clearing off all mud etc. followed by immersion/exposure for 5 minutes, or by application to surfaces using a spray, or pad soaked in disinfectant. Disinfectants can be applied using a spray applicator, although it may be necessary to use a bowl to dip paddles and other equipment. Iodophors are inactivated by prolonged exposure to light. When active they are a dark brown solution, becoming colourless when inactivated. Inactivated disinfectant should not be used. Always read product labels and follow the manufacturers instructions.