Survey and Mitigation for White Clawed Crayfish

Native of Britain White clawed crayfish is widely strewn in South and West Europe and has reached to northern Spain. Fast flowing streams are their typical habitats. They also find shelter in tree roots. These fishes are olive brown in color with pale-pink front claws that are used for collecting food and during breeding. They are of around 15 cm in size according to Ecological consultants these species play an important role in understanding ecological status of various water bodies. They are found almost throughout the year but can be found in abundance during autumn and summer because these are the times when water temperature is high. It is from during the late September that the female crayfish carries eggs and this continues till May.

But the recent studies say that white clawed crayfish are declining drastically and due to this these species are being protected under Wildlife and Countryside Act 1981. According to law selling, killing or advertising this fish would be considered as a legal offence and if found guilty the person would have to pay £5000 as fine. Moving further the studies also say that persistency of American signal crayfish has also been one of the main reasons of it getting declined because these species were extensively aggressive and carried plague that had adverse effects on aquatic living beings. This plague spread by the non-native species contaminated the water which resulted in around 95% loss of crayfish. Various programs are being encouraged for conserving white clawed crayfish.

Survey and mitigation for White clawed crayfish are carried by licensed ecology consultancies between mid of July to End of September because during this period the flow of river is low. Ecological consultants conduct survey during night by using torch. Mitigation is done by relocating the fishes if needed and by creating proper fencing.

Why is the White Clawed Crayfish important to be saved?

The White Clawed Crayfish (Austropotamobius pallipes) is the only native Cray fish species present in UK. In recent years the density of White clawed crayfish have declined in huge number and it’s been officially upgraded from “vulnerable” to “endangered” on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Due to its severe population decline it is protected under Wildlife and Countryside Act 1981 (as amended) and The Conservation (Natural Habitats, &c.) Regulations 1994, which states that to kill or injure or try to sell the white clawed crayfish is a legal offence and the person is guilty to pay fine of £5000.

White clawed crayfish has special characteristics i.e. they prefer to live in fresh water with more oxygen and their existence helps us understand how healthy our rivers are. The major cause of extreme decline in White clawed crayfish population is the non native species called signal crayfish, an origin of North America. These Signal Crayfish are larger than our native species which eats of all possible nutrients, not allowing other species to survive. Moreover the killer crayfish carries a plague which does not affect to itself but is vulnerably infectious to white clawed crayfish and other aquatic living beings. Due contaminated water and plague spread by Signal Crayfish, up to 70% of White clawed crayfish has lost their existence and is expected to extinct from the world if protective measure are not taken on time.

White clawed crayfish mitigation can help in saving the species. There is several mitigation schemes which can be designed based on white clawed crayfish habitat surveys. This includes translocation of the crayfish to save them from infected water or installation of stone walls and improving vegetation, etc. The public is required to identify the white clawed crayfish, be aware to protect them and take measure like to keep fishing nets clean and dry to not let the crayfish plague spread.