Population parameters of Melicertus kerathurus (Decapoda, Penaeidae) in southwest Sicilian shallow waters (Mediterranean sea) using length-frequency analysis.

The growth and mortality of the Caramote shrimp, Melicertus kerathurus (Forskål, 1775), in the shallow waters off southwest Sicily (central Mediterranean Sea) were estimated based on length-frequency data using the FISAT II software. The carapace length (CL) of the 1504 sampled shrimps ranged from 16.2 to 63.3 mm. Based on the CL frequency distribution, the shrimp population off the south-western Sicilian coast is composed of two dominant modes, representing shrimps of one and two years old, respectively, plus a few specimens up to three years old. The overall population growth parameters obtained from the seasonalized Von Bertalanffy growth function were: CL? = 72.00 mm, k = 0.78 yr-1, C = 0.29, and WP = 0.55. Total mortality, Z, based on the mean CL of shrimp in the catch, was 1.49 yr-1 using the Beverton & Holt equation and 1.28 yr-1 using the Ault & Ehrhardt equation. The instantaneous natural mortality M was 0.94 yr-1 and the exploitation ratio E was estimated between 26% and 37%. Based on the present data, it can be concluded that off the south-western coast of Sicily the Caramote prawn stock is currently experiencing an underfishing condition.