First record of Pteroplatytrygon violacea (Bonaparte, 1832) with annotation of cartilaginous fishes by-catch by gill nets (Egyptian Mediterranean)

摘要

Five cartilaginous fish species were recognized and identified as by-catch species during studying the catch of gill nets operated in the coastal area of Alexandria City from the Egyptian Mediterranean Waters during the study periods from Feb. 2018 to June 2018 and from Dec. 2019 to Nov. 2020. The by-catch included the first record ofPteroplatytrygon violacea, the closely related speciesDasyatis pastinacaandDasyatis tortonesei, the rarely found speciesRhinoptera marginata, and the blackchin guitarfishGlaucostegus cemiculus. Among these five species, four species are listed in the IUCN Red List; as least concern forP. violacea, data deficient forD. pastinacain the Mediterranean Sea, near threatened forR. marginata, and critically endangered forG. cemiculus. Morphological characters and morphometric measurements were studied to provide identification of these species. The species have been dissected for more biological information.