A Method of Marking Crayfish Astacus astacus Linné in Population Studies

Abstract

Marking adult crayfish (Astacus astacus L. 1758) was carried out by local cauterisation on the carapace so that both the pigment and the pigment producing tissue were destroyed. Well-delimited marks, observable even after two moults, were produced by a 100 watt soldering iron. A numerical system is presented which makes possible individual marking of up to 6,392 crayfishes. The method is illustrated by the results of an investigation of the growth of some Swedish populations of A. astacus. The method may be applied also to other decapode Crustacea, such as crabs and lobsters.