Additional and unusual captures of elasmobranch species from the northern coast of Tunisia (central Mediterranean)
The present paper reports occurrences of six elasmobranch species previously considered as rare and/or unknown in northern Tunisian waters. Captures of sharpnose seven-gill shark, Heptranchias perlo (Bonnaterre, 1788) and bluntnose six gills shark, Hexanchus griseus (Bonnaterre, 1788) showed that both species although they are threatened are not totally exctincted in the area. A new record of a juvenile great white shark, Carcharodon carcharias (Linnaeus, 1758) confirms one again that the central Mediterranean could be considered as a possible nursery area for this species. Additionally, captures of sandbar shark, Carcharhinus plumbeus (Nardo, 1827) and blackchin guitarfish Rhinobatos cemiculus E. Geoffroy Saint-Hilaire, 1817 are due to migrations from southern toward northern areas as a consequence of the warming of the latter areas. It may be also the case for blue shark, Prionace glauca (Linnaeus, 1758), from Algerian waters where the species is rather abundant.
Keywordsmigration nursery area water warming distribution measurements competition pressure
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