Biology of red mullet, Mullus barbatus (L. 1758), in the Gulf of Castellammare (NW Sicily, Mediterranean Sea) subject to a trawling ban

Under-or non-exploited areas are useful to aid in evaluating the potential productivity of fish stocks for sustainable fisheries. The Gulf of Castellammare (NW Sicily), where trawling has been banned since 1990, is a good site to study the biology and dynamics of low impacted fish populations. A total of 661 (595 female and 66 male) specimens of red mullet Mullus barbatus (95-245 mm total length, TL) obtained by monthly sampling from trammel net artisanal fishery, was collected in the Gulf of Castellammare from April 2006 to June 2007. Mature females occurred from April to September, with a peak in May. The mean Gonado-somatic index (GSI) also showed a May peak for both sexes. From Sagittae (642) readings the age structure ranged from age class I to VII in females and I to V in males. Female growth parameters, estimated according to the classic von Bertalanffy model, were: L-infinity = 221.2 +/- 11.51 mm standard error (SE), k(y)(-1) = 0.38 +/- 0.09 SE, t(0)(y) = -0.94 +/- 0.38 SE. The growth performance index (circle divide' = 2.27) was included in the range of values obtained by hard structure readings in the Central Mediterranean. Natural mortality (M-y(-1)) of females estimated by different methods ranged between 0.62 and 0.87 (mean value = 0.71 +/- 0.06 SE).