Chondrichthyes species in deep waters of the Mediterranean Sea

Abstract

SUMMARY: 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 Centroscymnus coelolepis. The most abundant species were Galeus melastomus and Etmopterus spinax. 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.

A Tale on the Demersal and Bottom Dwelling Chondrichthyes in the South of Sicily through 20 Years of Scientific Survey

“…[31]); however, it can reach a depth up to 800 m (in Ref. [44]). The maximum TL recorded was 150 cm (in Ref.…”

“…In the Mediterranean, C. monstrosa is usually caught by offshore trawlers mostly between 500 and 800 m (in Refs. [32,44]) and immediately discarded (in Ref. [8]).…”

Retinal specialisations in the dogfish <i>Centroscymnus coelolepis</i> from the Mediterranean deep-sea

“…During the DESEAS cruise in the Mediterranean (financed by the EC), it was caught at depths of 1500, 2500 and 2800 m (cf. Sion et al, 2004). As sharks occupy a high level in the marine trophic chain, identifying the special role of their sensory organs is one of the means of understanding their behavioural response.…”

Historical and contemporary records of the angular rough shark Oxynotus centrina (Chondrichthyes; Oxynotidae) in Turkish waters

“…O. centrina is a sluggish shark found over the continental shelf and upper slope at depth ranges generally between 60 and 660 m (COMPAGNO, 1984); however, a recent DESEAS survey revealed that lower limit of the depth range of the angular rough shark extends to 800 m in the western Ionian Sea (SION et al, 2004), and the upper limit may cover shallower areas around 30 m, as observed in the present study.…”

“…The rarity of O. centrina in the Turkish waters has become obvious after the most recent thorough investigations. O. centrina is considered to be a deepwater shark (COMPAGNO, 1984;SION et al, 2004); however, the present study has shown that it can ascend to shallower depths of around 30 m. Nocturnal excursions to shallow water by the angular rough shark increase the chance of incidental captures by coastal fishing gear, coastal gill-netting in particular. Furthermore, the shallower the angular rough shark occurs, the higher the chance of encountering divers.…”