How accurately are we describing the longline bycatch? The case of the ‘rare’ shark Alopias superciliosus in eastern Mediterranean

Abstract

The bigeye thresher shark, Alopias superciliosus, is a highly cosmopolitan species found in tropical and temperate seas worldwide. Its presence in the Mediterranean has been poorly documented while in the eastern Mediterranean, it has been confined on individual-based records and considered as scarce. Hereby, we provide evidences from two longline fishing trips of at least eight by-catch specimens. These represent the first confirmed presence of A. superciliosus in the waters of Cyprus and the first documentation of such a large occurrence of the species in the eastern Mediterranean. It is evidenced that the participation of scientific observers on-board is imperative in order to avoid misreporting and misidentification of by-catch species, and enable a correct and representative assessment of the marine resources. Finally, the incorporation of underwater cameras during the scientific programmes is encouraged since it can provide insights on the species identity and post-release mortality of the discarded specimens.