Unexpected massive enmeshments of the Sharpchin barracudina Paralepis coregonoides Risso, 1820 in mesopelagic sediment traps in the Levantine Basin, SE Mediterranean Sea

Abstract

This study reports exceptional penetrations of the Sharpchin Barracudina Paralepis coregonoides into pelagic, open-sea sediment traps in the Levant Basin of the SE Mediterranean Sea. This first substantiated record of the species at the Levant Basin has been observed in two sediment traps at 180 and 280 m depth, 50 km offshore the coast of Israel. Over one year of deployment (November 2016 till November 2017), 483 adult individuals have been repeatedly entrapped inside the automatic sediment traps that were covered with a 25 mm baffler mesh for the first half year and then replaced with a smaller 10 mm mesh for the second half. This undesirable catch of such an elusive and understudied species enabled us to revise its distribution, abundance and genetic divergence. The continuous entrapment throughout the year of sexually mature individuals has confirmed that this species is common to the SE Mediterranean. In order to avoid unwanted entrapments that disrupt biogeochemical sediment studies, the installation of small mesh size nets on the conventional sediment trap openings must be considered in the pelagic zone of the SE Mediterranean, and probably elsewhere.