Biology of the Mountain Crayfish Euastacus sulcatus Riek, 1951 (Crustacea: Parastacidae), in New South Wales, Australia

Abstract

The biology and distribution of the threatened Mountain Crayfish Euastacus sulcatus, was examined through widespread sampling and a long-term mark and recapture program in New South Wales. Crayfish surveys were undertaken at 245 regional sites between 2001 and 2005, and the species was recorded at 27 sites in the Clarence, Richmond and Tweed River drainages of New South Wales, including the only three historic sites of record in the state, Brindle Creek, Mount Warning and Richmond Range. The species was restricted to highland, forested sites (220-890 m above sea level), primarily in national park and state forest reserves. Adult crayfish disappear from the observable population during the cooler months, re-emerging in October when the reproductive season commences. Females mature at approximately 50mm OCL, and all mature females engage in breeding during a mass spawning season in spring, carrying 45-600 eggs. Eggs take six to seven weeks to develop, and the hatched juveniles remain within the clutch for a further 2.5 weeks. This reproductive cycle is relatively short, and represents a more protracted and later breeding season than has been inferred for the species in Queensland. A combination of infrequent moulting and small moult increments indicated an exceptionally slow growth rate; large animals could feasibly be 40-50 years old. Implications for the conservation and management of E. sulcatus are discussed.