Life cycle of the deep-water pandalid shrimp Plesionika edwardsii (Decapoda, Caridea) in the central Mediterranean Sea

The reproduction, growth and population dynamics of the deep-water pandalid shrimp Plesionika edwardsii Brandt were studied in the South Tyrrhenian Sea (central Mediterranean Sea, Italy). Individuals were collected between 100- and 350-m depth during an experimental trap survey conducted in the April 1998-November 1999 period. The mean catch did not show differences in relation to either sampling depth or season. Reproduction appeared to be continuous throughout the year even if the main reproductive activity occurred in April-July. The small ovigerous females were 15.5 mm CL, whereas the mean size at which 50% of females were ovigerous (L-50) was 18 mm CL. Differences in size at maturity were recorded during the year. The L50 reached the minimum value in June and maximum in October-November, at the end of the breeding season when the reproductive stock was composed mainly of a few large females. A main recruitment cohort was observed in January, although new cohorts of juveniles appeared in each sampling period. Tire von Bertalanffy growth curve parameters were estimated for both sexes using the relative mean carapace lengths at ages. Females grew faster and reached larger size after maturity than males. Longevity was estimated to be around 3.5 years for both sexes.