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This paper reports the weight-length relationship (WLR) for thirty-eight fish species from the Gulf of Castellammare (NW Sicily, Mediterranean Sea). A total of 59 870 fish were collected and measured during four seasonal trawl surveys carried out in 2005 at 10 to 200 m depth. The b parameter of the WLRs ranged from 1.79 ( Cepola macrophthalma) to 3.56 ( Conger conger). Significant differences in both a and b values among seasons were detected for eight species. Moreover, the condition factors (as weight-at-length) of Merluccius merluccius and Mullus barbatus were compared in different area/year combinations characterized by the presence or absence of trawling impact. While M. barbatus showed a higher condition factor in trawled areas/years, possibly due to density-dependent factors linked to the increased biomass in the no-trawl area, no such link was detected in M. merluccius. [ABSTRACT FROM AUTHOR]

Describes the rediscovery of the diogenid, Paguristes syrtensis de Saint Laurent, 1971, in a shallow-water Posidonia oceanica Delile bed along the coast of southwest Sicily, Italy. Retention of the color pattern after 15 months of fixation; Morphological characteristics; Habitat preference.

This study examines the impact of bottom trawl fishing on the macrobenthic communities inhabiting the coastal terrigenous mud off the northern coast of Sicily (Western Mediterranean). Two intensely trawled gulfs were compared with two gulfs from which trawling has been excluded for 15 years. The results show a significant effect of trawling on the faunal assemblage and when comparing the mean biomass and the whole isotopic composition of the benthic communities. A similar pattern, although not significant, was found for total abundance, biomass, production/biomass ratio and diversity. Higher abundance and lower biomass were found in the untrawled areas, attributable to the presence of more numerous yet smaller individuals, possibly a consequence of more abundant larger predators that are not removed by trawling, and consequent higher predatory pressure on the benthic macrofauna. The SIMPER analysis evidenced a dominance of burrowing deposit feeding worms (Paraonidae and Cossuridae) in trawled areas, as a result of increased mechanical alteration and hence more organic matter available as food. In contrast, the response to trawling as drawn by the use of trophic markers (i.e., stable isotopes) was less clear. While δ 15 N of benthic taxa did not vary significantly between untrawled and trawled areas, δ 13 C was higher in trawled areas possibly due to high sediment resuspension and consequent intense microbial activity. Mixing models confirmed higher reliance to a detritus-based food web for benthic organisms in the trawled areas. Standard Ellipse Areas (SEAc) as a measure of community niche width were slightly larger in trawled areas, likely due to higher generalism triggered by alteration/removal of the original benthic community. [ABSTRACT FROM AUTHOR]

A pilot experiment of marine ranching using hatchery-reared juveniles of white seabream, Diplodus sargus, was made in the Gulf of Castellammare (NW Sicily). The research aimed at evaluating (i) if artificial reefs are suitable for the settlement of reared young seabreams, (ii) what are the main causes of mortality and (iii) the growth rate of released fishes in the open sea. A total of 6930 tagged cultured juvenile white seabreams (305 days old) were released in an artificial reefs (AR) area. Underwater visual census, sightings and recaptures were used as a source of data for estimating abundance and size of released fishes. The survey lasted 15 months and was carried out in artificial (AR, breakwaters and harbours) and natural (river mouths, rocky bottoms and Posidonia oceanica meadows) coastal habitats of the Gulf. A few days after the release, more than 90% of the tagged seabreams left AR and moved mainly towards harbours and breakwaters, which resulted to be particularly suitable for their settlement and growth. The recapture was 8.2% of the released stock. During the first days after releasing, the main ascertained sources of mortality were professional fishing (6.7%) and predation by conger eel, Conger conger (1.1%). A behavioural deficit of the reared seabreams in the use of refugia and food was observed in the initial period following the release. The results obtained provide some management suggestion for the feasibility of marine ranching initiatives involving hatchery-reared fishes. [Copyright &y& Elsevier]