Threatened Sharks in Low Oxygen Waters of the Sea of Marmara Highlight Potential Challenges for Conservation

ABSTRACT Despite the ongoing and increasingly disruptive process of deoxygenation, deep–sea sharks Hexanchus griseus , Centrophorus uyato , and Oxynotus centrina , continue to access the hypoxic slope waters of the northern Sea of Marmara although the frequency of such excursions remains unknown. This study shows that H. griseus , C. uyato , and O. centrina can tolerate at least moderately hypoxic conditions and may have the potential for much higher hypoxic tolerance than previously appreciated. Investigating the spatial and depth distribution of mesophotic habitats, mainly composed of Eunicella cavolini and Savalia savaglia in the bathyal zone, and investigating their potential use by deep–sea sharks are essential steps for future shark conservation and management plans.