Distribution and in vivo Observations of the Boa Dragonfish Stomias boa (Stomiidae) in Deep-Sea Canyon Ecosystems of the Northwestern Mediterranean Sea

An remotely operated vehicle survey conducted in three Canyon heads of the Ligurian Sea (northwestern Mediterranean Sea) in 2022 documented the presence of the boa dragonfish, Stomias boa (Risso, 1810), belonging to the family Stomiidae. Overall, 112 specimens of this meso- and bathypelagic species were primarily observed at depths ranging from 350 to 400 m, with the highest number recorded in Bergeggi (n = 59, in a single dive). This study significantly contributes to our understanding of the behaviour of S. boa by providing novel insights, including the description of a yawn-like action. Furthermore, by utilizing data from public geodatabases and incorporating new records, an updated distribution map of S. boa in the Mediterranean Sea was generated, encompassing a total of 2266 specimens and 1443 occurrence points, indicating a widespread presence of this species throughout the Mediterranean Sea. These findings contribute to the understanding of the species abundance and behaviour to environmental stimuli in deep-sea Canyon ecosystems.