Biological and ecological aspects of the blackmouth catshark, Galeus melastomus Rafinesque, 1810, from the Southern Tyrrhenian Sea

Data on the biology and ecology of Galeus melastomus are old/absent for the SouthernTyrrhenian Sea, despite there being numerous studies in the wider area. A total of 127 specimens ofG. melastomus from the southern Tyrrhenian Sea, collected in 2018-2019 using trawling nets, wereanalyzed to investigate size at sexual maturity, sex ratio, length-weight relationships, and feedinghabits. To our best knowledge, this is the first time in which all these features were investigated in theSouthern Tyrrhenian Sea for G. melastomus. The stomach content analysis showed that G. melastomushad intermediate feeding habits, preying on a great variety of species, especially Cephalopoda,Osteichthyes, and Crustacea. The Levin's index value (Bi) was 0.53. Sex ratio was 0.92:1, with femalesslightly more abundant and bigger than males. The results also showed a decrease (33.7 cm forfemales, 31.1 cm for males) in length at 50% maturity (L50). This could be a result of anthropogenicstressors, such as overfishing and/or and environmental changes, which can induce physiologicalresponses in several species. Our results highlighted the differences related to sexual maturity,growth, and feeding habits of the blackmouth catshark in the studied area, providing reference datato allow comparison with future studies on this species adaptations to this and other deep-sea areasin the Mediterranean Sea.