Size At Sexual Maturity in Red Shrimp Females, Aristaeomorpha Foliacea, From the Sicilian Channel (Mediterranean Sea)

Abstract

Abstract This paper reports on the maturity pattern and the estimation of length at sexual maturity for Aristaeomorpha foliacea females, based on two years of seasonal research trawl surveys. Two approaches were used: gonadic condition (empirical scale) and presence/absence of spermatophores. Ready-to-spawn females (IV stage) occurred almost exclusively in summer throughout the area surveyed. Distribution of the proportion of "mature" (III + IV stages) females showed the classic "sigmoid" shape but with a general failure to attain 100% maturity, even though in the largest size classes there is substantial inter-year variability. The presence of spermatophorcs, however, being a sign of adulthood, with almost all the medium/large specimens positive, showed a better approximation to the sigmoid curve. An attempt to combine the two curves, in order to more precisely identify the length at maturity, is illustrated and discussed. The logistic model has been chosen in a form that allows the asymptote to be < 1. The maximum reproductive potential is defined as the point of intersection of the two curves (spermatophores and maturity). This maximum is reached after about 18 months, at a carapace length of 40 mm.