Scientists have studied a developing lake population of the introduced spiny-cheeked crayfish (Orconectes limosus) in the UK to assess the feasability of control to prevent its spread into adjacent water bodies.
The results of the study are published in a paper by David Holdich and John Black in a recent issue of the journal Aquatic Invasions.
Although the spiny-cheeked crayfish had been introduced into continental Europe in 1890 and has spread rapidly there, it was not recorded in the UK until more than a hundred years later (in 1995), with the first occurrence in the wild reported in 2000.
The authors report that the main source ...seems to be from anglers introducing them into fish ponds to improve production, or members of the public releasing aquarium pets into natural waters...
The authors studied an established population of crayfish in Clifton Pond, a water-filled gravel pit near Nottingham.
Although large numbers of crayfish appeared to be present (they are thought to have been introduced there 4 or 5 years ago), they were not easily caught with traps throughout the year, except in September and October.
Mating and egg-laying were observed in the spring, with the authors speculating that O. limosus may reproduce twice a year. The species was also observed to form burrows at the site.
Although none of the populations of O. limosus in the UK appear to threaten the native white-clawed crayfish (Austropotamobius pallipes), the potential for spread as an invasive species still exists, along with the additional danger of acting as a vector for crayfish plague.
Because of the low catch efficiency, the authors suggest that the only way of effectively controlling the population (at least at the study site) would be to use natural biocides (which would involve a lot of money, time and effort) or physical (dewatering) means (which might not completely eradicate the crayfish, given that they burrow).
For more information, see the paper: Holdich, D and J Black (2007) The spiny-cheek crayfish, Orconectes limosus (Rafinesque, 1817) , digs into the UK. Aquatic Invasions 2, pp. 1"16.