Abstract
Bibliographic and data gathered in scientific bottom trawl surveys carried out off the Southern Coasts of Sicily (Mediterranean Sea), from 1994 to 2009 and between a depth of 10 and 800 m, were analysed in order to prepare a checklist of demersal sharks and chimaera, which are species sensitive to fisheries exploitation. Out of the 27 previously reported demersal shark and chimaera taxa in the Mediterranean, only 23 were found in literature and 20 sampled during the surveys in the investigated area. Among the species sampled in the surveys, only 2 ubiquitous ( Squalus blainville and Scyliorhinus canicula ) and 3 deep-water ( Chimaera monstrosa , Centrophorus granulosus and Galeus melastomus ) species showed a wide geographical distribution with a consistent abundance. Excluding the rare (such as Oxynotus centrina ) or uncommon shark (e.g. Squalus acanthias ), the estimated frequencies of occurrence and abundance indexes show a possible risk of local extinction for the almost exclusively (e.g. angelshark, Squatina spp.) or preferential (e.g. Scyliorhinus stellaris ) neritic species.
Highlights
Chondrichthyes are generally considered among the most sensitive species even to low fishing pressures
Among the 27 demersal sharks and chimaera recognized in the Mediterranean Sea [51,52,53,54,55], which belong to five orders (Chimaeriformes, Hexanchiformes, Squaliformes, Squatiniformes and Carcharhiniformes), four species (Hydrolagus mirabilis, Hexanchus nakamurai, Centroscymnus coelolepis and Galeus atlanticus) were never reported in the investigated area
The grand means and corresponding standard deviations and r figures are reported in table 2 (MEDITS) and table 3 (GRUND), while the results of the statistical analyses are reported in table 4 (MEDITS) and table 5 (GRUND)
Summary
Chondrichthyes are generally considered among the most sensitive species even to low fishing pressures. Demersal sharks and chimaera share the same life traits of their benthic batoid and pelagic counterparts, including a high position in the trophic food webs, slow growth, delayed sexual maturity, low fecundity and long life spans [1,2,3,4]. These animals have always represented a common by-catch of the bottom trawl fleets operating on the fishing grounds located between Southern Sicily and the Northern Coasts of Africa since the 70’s and 80’s. More recent studies have shown that shark do not feed on red shrimps [1,9,10]
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