Assessing the current and projected distributions of temperate sharks and rays in southeastern Australia

Elasmobranchs, including sharks and rays, face growing threats, with a quarter of species globally at risk of extinction. In southeastern Australia, climate change (e.g., increasing temperatures), further pressures these species. However, limited knowledge exists on how climate change will affect elasmobranchs in temperate regions or how effective marine protected areas (MPAs) are in safeguarding them. This study modelled the influence of environmental variables on elasmobranch distribution and abundance off Victoria's coast using data from 1048 baited remote underwater video stations (BRUVS) and six oceanographic and habitat layers. Models were used to assess key environmental drivers, then projected under two climate scenarios (RCP4.5 and RCP8.5) to predict future changes and evaluate MPA effectiveness. Sea surface temperature and wave environment were the strongest predictors of abundance, though model performance varied (15–68 % deviance explained; test correlation r = 0.25–0.75). Cephaloscyllium laticeps (Draughtboard Shark) had the best-performing model, while Notorynchus cepedianus (Broadnose Sevengill Shark) had the poorest. Climate projections indicated overall declines in abundance by 2090, especially for Trygonorrhina spp. (Fiddler Rays), though some species, such as Mustelus antarcticus (Gummy Shark), may increase locally. Present-day MPA coverage of suitable habitat was limited (average 17 %) but increased under future scenarios (up to 27 %) as predicted species distributions shifted. C. laticeps had the highest predicted protection (up to 58 %), while Southern Eagle Rays (Myliobatis tenuicaudatus) had the lowest. Though MPA effectiveness varied across species and scenarios, it generally increased under projected climate conditions. These findings offer insight for improving conservation and management of temperate elasmobranchs under climate change.