Growth with age in the freshwater crayfish, Euastacus spinifer "(Decapoda: Parastacidae)", from the Sydney Region, Australia

Growth with time of different sub-groups in the Euastacus spinifer population in two pools of the Loddon River has been measured and assessed. Annual increments of newly released juveniles maintained in captivity match predicted values from the linear regression calculated from large field samples (sub-adults, mature males <55mm CL). No difference in growth related to sex, could be detected and the decline in annual growth (again a linear relationship) for all specimens above 55mm CL is partially due to lowered moulting frequency, to a single annual moult. Normal males mature at about 5 years (45-55mm CL), while females do not reach maturity until 8 years (-70mm CL) or older. Mean carapace length at age can be estimated with confidence up to at least 8 years; with calculated ages, for the largest specimens recorded at the study site, ranging from 22-39 years. Reports suggest that in some areas E. spinifer can attain a size (160mm CL) and weight (1.8kg) which place it among the largest of parastacid species.