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

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.

Fishery and Biology of Aristaeomorpha foliacea (Risso, 1827) (Crustacea: Decapoda) in the Northern Tyrrhenian Sea (Western Mediterranean)

“…Data on reproductive activity are consistent with findings for the central Mediterranean Mura et al, 1992;Ragonese and Bianchini, 1995;D'Onghia et al, 1998). Females exhibit an extended reproductive period, from spring to autumn, with a peak between July and September.…”

“…Percentage of large individuals is very low. During the spring months, an early component can be found, corresponding to the cohort of trawl net recruits, as already reported in the literature (Ragonese and Bianchini, 1995;D'Onghia et al, 1998;Spedicato et al, 1998).…”

“…However, a patchy distribution is also observed. Thus the species is scarce or absent in the Catalan Sea, in the Gulf of Lions and in the Ligurian Sea (Sardà, 1986, Campillo, 1994Orsi Relini and Relini, 1994), abundant in Tunisia (Ben Marien, 1994) and weakly present in Algeria (Yahiaoui, 1994), outnumbers A. antennatus in the northern Tyrrhenian Sea (Campillo, 1994;Biagi et al 1998) and in the Sicilian channel (Ragonese and Bianchini, 1995), is present in almost equal proportions in the southeastern Tyrrhenian Sea (Greco et al, 1994) and again less abundant in the Ionian Sea (Pipitone and Andaloro, 1994;D'Onghia et al, 1998).…”

“…It was defined as the size corresponding to the intersection of the gonadic maturity curve and the mating complementary curve (i.e. absence of spermatophore) during the maximum reproductive activity of the stock (Ragonese and Bianchini 1995;D'Onghia et al, 1998).…”

“…Most of the information relates to Italian waters of the central Mediterranean Ragonese, 1989;, Mura et al, 1992Bianchini and Ragonese, 1994;Ragonese et al, 1994Ragonese et al, , 1997Matarrese et al, 1995;Ragonese and Bianchini, 1995;DOnghia et al, 1998;Bianchini et al, 1998;Bianchini, 1999). Only scanty attention is devoted to the western basin (Lumare and Utzeri, 1973;Bianchini and Ragonese, 1994).…”