Abstract

The distribution and biology of the powerful crayfish, Euastacus valentulus Riek 1951, was examined through long-term monitoring at Iron Pot Creek and regional surveys at 245 sites in New South Wales, Australia. The species was recorded from 35 sites in the Clarence, Richmond, Tweed and Brunswick River catchments, in a wide range of habitats from 10 – 530 m above sea level. Limited recapture data indicated an absolute growth rate of ~0.7 mm per month. A maximum size of 110 mm OCL was recorded, with onset of female maturity at ~69 mm OCL. However, western animals were distinctly smaller, maturing at 40–45 mm OCL and attaining a maximum 65 mm OCL. The species was reproductively active in winter to spring; females at Iron Pot Creek carried fewer eggs (120–400) than eastern females (180–1,000+), and were collected over a longer period (June – November, cf. July – September). Eggs took approximately 7 weeks to hatch, with a further 4 weeks until juveniles became independent. GIS analysis of confirmed sites produced an Extent of Occurrence of 5436 km². However, the biological differences recorded coincide with an obvious distribution gap, suggesting the possibility of cryptic speciation and/or fragmentation of the species across its range.

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