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

Abstract

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 of Pteroplatytrygon violacea, the closely related species Dasyatis pastinaca and Dasyatis tortonesei, the rarely found species Rhinoptera marginata, and the blackchin guitarfish Glaucostegus cemiculus. Among these five species, four species are listed in the IUCN Red List; as least concern for P. violacea, data deficient for D. pastinaca in the Mediterranean Sea, near threatened for R. marginata, and critically endangered for G. cemiculus. Morphological characters and morphometric measurements were studied to provide identification of these species. The species have been dissected for more biological information.