Chondrichthyes species in deep waters of the Mediterranean Sea

Letizia Sion,Francesca Capezzuto,Michele Panza,Gianfranco D’Onghia,Anna Bozzano

doi:10.3989/scimar.2004.68s3153

Abstract

Data collected during the DESEAS survey carried out in three areas of the Mediterranean Sea (Balearic Sea, western and eastern Ionian Sea) were used to describe the distribution and abundance of chondrichthyes species at depths between 600 and 4000 m. A total of 8 chondrichthyes species were recorded, 5 of them in the Balearic Sea, 4 in the western Ionian and 6 in the eastern Ionian. A decrease in abundance with depth was observed in each species with the exception of Centroscymnuscoelolepis. The most abundant species were Galeus melastomus and Etmopterusspinax. The depth range of some species was updated. G. melastomus was caught down to 1500 m, exhibiting a smaller-deeper pattern in females, while E.spinax was captured down to 2200 m with a bigger-deeper trend. Mature females of these two sharks were found between 600 and 1500 m. A wide size-range was shown in both species. C.coelolepis was only collected in the Balearic Sea down to 2800 m. The presence of a pregnant female was sampled from a depth of 1500 m. The distribution of the species is discussed in the context of the present knowledge of the Mediterranean ichthyofauna.

Highlights

A decrease in abundance with depth was observed in each species with the exception of Centroscymnus coelolepis
The fish fauna in the Mediterranean Sea consists of 664 species, of which 86 are represented by chondrichthyes (Quignard and Tomasini, 2000)
This paper presents the results of deep-sea chondrichthyes species collected during this research

Summary

Introduction

The fish fauna in the Mediterranean Sea consists of 664 species, of which 86 are represented by chondrichthyes (Quignard and Tomasini, 2000). Cartilaginous fishes represent by-catch of the commercial fisheries in the Mediterranean, their importance as indicators of the “top down” effect in the food webs and overexploitation by fishery is currently under discussion for this basin (Serena et al, 2002) Their position at the top of the marine food webs in addition to their life-history k-strategies make chondrichthyes more susceptible to overfishing and to man-induced environmental changes (e.g. Stevens et al, 2000; Vacchi and Notarbartolo di Sciara, 2000). In this respect, a specific international plan of action has recently been proposed for the conservation and management of Mediterranean cartilaginous fish (Serena et al, 2002). The importance of such an action plan is linked to the awareness of the fragmentary knowledge on their biology and ecology, even for the more common species

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Discussion

Conclusion