Recruitment Areas of Demersal Species in the Straits of Sicily (Central Mediterranean)

Locating nursery grounds of exploited demersal species is essential for implementing management measures aimed at reducing the fishing pressure on vulnerable stages of species life cycle and their habitat. The aim of this study was to identify the nursery areas of seven important commercial species of the northern sector of the Straits of Sicily (central Mediterranean): European hake, Red mullet, Greater forkbeard, Deep-water rose shrimp, Giant red shrimp, Norway lobster, Horned octopus. The data were collected during experimental trawl surveys carried out routinely in the Straits of Sicily from 1994 to 2004 during spring and autumn season. The analysis was performed using the following three-step approach. Firstly the juvenile fraction (recruits) of a species was identified and the relative density indices by haul were estimated. In a second step, yearly distribution maps of recruit density indices were generated through geostatistical analysis. Hence the areas encompassing the highest concentrations of recruits each year were delineated (density hot-spots). Finally, the persistence in time of the density hot-spots was evaluated to identify the stable nursery areas. Results showed that most of the species have nursery grounds well defined and very stable in time. Protection of these areas, through limitations of fishing pressure throughout the year or during selected months, is an important management measure for ensuring the long-term sustainability of fisheries