The spiny-cheek crayfish, Orconectes limosus (Rafinesque, 1817) [Crustacea: Decapoda: Cambaridae], digs into the UK

The invasive, plague-carrying, North American spiny-cheek crayfish, Orconectes limosus, has apparently only recently reached the UK despite being first introduced into continental Europe in 1890. A number of populations have now developed over a wide geographic area in England. It is thought that these have arisen from deliberate introductions by anglers or from aquarium pets being released by the general public. O. limosus probably poses as great a threat to the indigenous white-clawed crayfish, Austropotamobius pallipes, in the UK as does the North American signal crayfish, Pacifastacus leniusculus. Like the signal crayfish, O. limosus burrows extensively. A developing lake population of O. limosus has been studied by trapping and direct observation for the first time in the UK to see whether it could be controlled before it spreads to adjacent lakes and a river. Although large numbers appear to be present they are not easily caught in traps and the CPUE over the year of trapping was low (1.28), although in certain months, i.e. September and October, it was relatively high (2.0). Trap catches were dominated by adult males. Mating and egg-laying took place in the spring. A berried female of 62 mm CL and a male of 65 mm CL were found, which were probably at least four years old. A review of the life-history of O. limosus is also undertaken as there appears to be some variation within Europe, with two periods of mating being reported for some populations. The only way to control the population would appear to be by chemical or physical (dewatering) means.