New insights on the ecology and biology of the rare shark species Oxynotus paradoxus from recent records

Graça Aranha Carvalho Ramos, Sofia; Dias, Ester; Marsili, Tiago; Pires da Rocha, Pedro; Teodosio, Maria; Figueiredo, Ivone

http://hdl.handle.net/10400.1/28599

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Autores

Graça Aranha Carvalho Ramos, Sofia

Dias, Ester

Marsili, Tiago

Pires da Rocha, Pedro

Teodosio, Maria

Figueiredo, Ivone

Resumo(s)

Oxynotus paradoxus, documented in the Eastern Atlantic Ocean from Senegal to Scotland at depths ranging between 92 and 1044 m, has been a subject of limited scientific attention in Portugal. Despite its presence in various Portuguese occurrence checklists, only two scientific studies have reported O. paradoxus, one off the mainland and the other off the Azores islands. In this study, conducted during fishing campaigns, four O. paradoxus specimens were caught off the southwest coast of Portugal (SW Iberian Peninsula) at depths ranging between 742 and 1238 m. Notably, an adult female achieved a new maximum depth record for this species, measuring 650 mm in total length. By examining this adult female, we provide novel insights into the ecology and biology of O. paradoxus. Morphometric measurements are compared with previous studies, revealing some intra-specific variability. The observed low hepato-, gonadosomatic, and ecophysiological indices suggest that the adult female had refrained from feeding for some time before collection. This individual-focused approach contributes significantly to the understanding of this poorly known species, especially considering its rarity. This study marks a noteworthy effort to enhance knowledge and emphasizes the importance of individual-based investigations when targeting rare species.