Untitled - CNR

Recruitment Areas of Demersal Species in theStrait of Sicily (Central Mediterranean)G. Garofalo 1 , M. Gristina 1 , T. Fortibuoni 2 , G.B. Giusto 1 , G. Sinacori 1 , F.Fiorentino 11, Institute for Coastal Marine Environment, CNR, Mazara del Vallo (TP), Italy2, Institute for Environmental Protection and Research, Technical-Scientific Structure ofChioggia (VE), Italygermana.garofalo@iamc.cnr.itAbstractLocating nursery grounds of exploited demersal species is essential for implementingmanagement measures aimed at reducing the fishing pressure on vulnerablestages of species life cycle and their habitat. The aim of this study was to identifythe nursery areas of seven important commercial species of the northern sector ofthe Strait of Sicily (central Mediterranean): red mullet, European hake, horned octopus,deep-water rose shrimp, greater forkbeard, Norway lobster and giant red shrimp.The data were collected during experimental trawl surveys carried out routinely inthe Strait of Sicily from 1994 to 2004 during spring and autumn season. The analysiswas performed using the following three-step approach. Firstly the juvenile fraction(recruits) of a species was identified and the relative density indices by haul wereestimated. In a second step, yearly distribution maps of recruit density indices weregenerated through geostatistical analysis. Hence the areas encompassing the highestconcentrations of recruits each year were delineated (density hot-spots). Finally, thepersistence in time of the density hot-spots was evaluated to identify the stable nurseryareas. Results showed that most of the species have nursery grounds well definedand very stable in the long term. The protection of these areas, through limitations offishing pressure throughout the year or during selected months, may be an importantmanagement measure for ensuring the long-term sustainability of fisheries.1 IntroductionThe spatial ecology of fishery targetspecies is a major issue of current fisheriesresearch [1]. The spatial structure ofpopulations, the location of nurseries andspawning grounds, the ontogenetic movementsand migration patterns, are investigatedin order to better understand the reproductiveecology of fish species and implementeffective fishery management. Indeed,the reproductive success and subsequentrecruitment of young fish to theirparent stocks is one of the most importantfactors regulating the annual abundanceof populations [2]. Accordingly,fishery managers should strive to reducefishing mortality of the critical fractions ofthe stocks (e.g. adult/spawners and juveniles/recruits).Most recent research suggeststhat understanding the spatial distributionof stock fractions and their dynamics,and implementing consistent spatiallyexplicit management measures, such as