Aspects of the biology of the freshwater crayfish Euastacus spinifer (Heller) (Decapoda: parastacidae)

Abstract

A study of the freshwater crayfish Ehastacus spinifer (Heller) was conducted near Sydney, N.S.W., with the aim of describing the reproduction, growth, population structure and feeding habits of this crayfish under natural conditions. Reproductive mechanisms were compared to those of other parastacids, and seasonal reproductive activity was determined from changes through time in the breeding condition of wild females. The gonopore setae of females and the genital papillae of males were established as field indicators of maturity by comparison with laboratory determinations of gonad weight and maturity, and, in the case of females, with breeding condition in the wild population. Sizes at the attainment of maturity were thus determined for both males and females, and two reproductive types of males were described. Population structure was interpreted from the composition of catches, according to the results of tests for equal average catchabilities of crayfish in different sex- and size-groups based on recapture data. Studies of growth were based primarily on the resuls of mark-recapture studies, and a number of statistical methods were combined to form a routine for the extraction of information on moult increments from mark—recapture data.