Integrating migratory connectivity data into the conservation of Australian sharks and rays

Understanding migratory connectivity is important for conserving highly mobile marine species facing escalating threats. Establishing baseline information on migratory connectivity is necessary for identifying species and regions requiring transboundary cooperation for their conservation. Despite efforts to track migratory sharks and rays, information on transboundary movements is limited and often inaccessible to managers and policymakers. To address this gap, we synthesized movement information from published studies for Australian shark and ray species listed under the Convention on Migratory Species (CMS) and investigated which species require international engagement to support their population recovery. We built connectivity networks from telemetry and mark-recapture studies to provide the first transboundary connectivity baseline for Australian sharks and rays. Of the 29 CMS-listed shark and ray species reviewed, we identified five species linking the Australian Exclusive Economic Zone to other national jurisdictions via migratory connections through the Tasman Sea to New Zealand, through the Tasman and Coral Sea to New Caledonia, and north across the Timor Sea and Torres Strait. White sharks (Carcharhinus carcharias) and whale sharks (Rhincodon typus) were the most data-rich species, whereas 18 species (62%) had no movement data available. Overall, we identified 64 studies for only 12 species, indicating that conservation and management of only a few CMS-listed sharks and rays are informed by understanding their movement, whereas the migratory connectivity of most species remains unknown. These results underscore the need for expanded, multilateral, and species-specific movement studies. Notably, almost two-thirds of endangered or critically endangered migratory sharks and rays had only one or no published studies on their movements. Finally, our results demonstrated the potential for this baseline information to support (or not) the listing of migratory species under CMS. Additionally, this work shows that migratory connectivity baselines can support international reporting, direct international collaboration, and research efforts on critical knowledge gaps.