On size and sexual dimorphism in Austropotamobius pallipes (Lereboullet) : A step in assessing the commercial exploitation potential of the native British freshwater crayfish

Abstract

Interest in crayfish farming in Great Britain is currently very high. Attention is drawn in this paper to the naturally occurring British crayfish resource. The unexploited native crayfish Austropotamobius pallipes is examined with respect to size and sexual dimorphism of the chelipeds and abdomen, with a view to aiding assessment of the possible commercial potential of this species. Individuals can be designated mature or immature regarding production potential on the basis of a sudden increase in the size of the chelipeds at 29.0 and 30.7 mm carapace length for males and females, respectively. A disproportionate increase in abdomen width is also recorded for females at the 24.0 mm carapace length stage. This probably represents the onset of sexual maturity. The importance of a consideration of reproductive efficiency in a cropping strategy is emphasised. Conclusions can thus be drawn as to the acceptability of the size of the British crayfish, which is present in large populations in some areas. An attempt has been made to provide quantitative guidelines as to expected size, and a size above which crayfish may be more productively cropped is also suggested. On the basis of current data, this species appears to be at no major disadvantage with regard to these size parameters when compared with other crayfish species being marketed.