Since the 1950s, industrial fisheries have expanded globally, as fishing vessels are required to travel further afield for fishing opportunities. Technological advancements and fishery subsidies have granted ever-increasing access to populations of sharks, tunas, billfishes, and other predators. Wilderness refuges, defined here as areas beyond the detectable range of human influence, are therefore increasingly rare. In order to achieve marine resources sustainability, large no-take marine protected areas (MPAs) with pelagic components are being implemented. However, such conservation efforts require knowledge of the critical habitats for predators, both across shallow reefs and the deeper ocean. Here, we fill this gap in knowledge across the Indo-Pacific by using 1,041 midwater baited videos to survey sharks and other pelagic predators such as rainbow runner ( Elagatis bipinnulata ), mahi-mahi ( Coryphaena hippurus) , and black marlin ( Istiompax indica) . We modeled three key predator community attributes: vertebrate species richness, mean maximum body size, and shark abundance as a function of geomorphology, environmental conditions, and human pressures. All attributes were primarily driven by geomorphology (35%−62% variance explained) and environmental conditions (14%−49%). While human pressures had no influence on species richness, both body size and shark abundance responded strongly to distance to human markets (12%−20%). Refuges were identified at more than 1,250 km from human markets for body size and for shark abundance. These refuges were identified as remote and shallow seabed features, such as seamounts, submerged banks, and reefs. Worryingly, hotpots of large individuals and of shark abundance are presently under-represented within no-take MPAs that aim to effectively protect marine predators, such as the British Indian Ocean Territory. Population recovery of predators is unlikely to occur without strategic placement and effective enforcement of large no-take MPAs in both coastal and remote locations.

Tristan da Cunha Islands, an archipelago of four rocky volcanic islands situated in the South Atlantic Ocean and part of the United Kingdom Overseas Territories (UKOTs), present a rare example of a relatively unimpacted temperate marine ecosystem. We conducted the first quantitative surveys of nearshore kelp forests, offshore pelagic waters and deep sea habitats. Kelp forests had very low biodiversity and species richness, but high biomass and abundance of those species present. Spatial variation in assemblage structure for both nearshore fish and invertebrates/algae was greatest between the three northern islands and the southern island of Gough, where sea temperatures were on average 3-4o colder. Despite a lobster fishery that provides the bulk of the income to the Tristan islands, lobster abundance and biomass are comparable to or greater than many Marine Protected Areas in other parts of the world. Pelagic camera surveys documented a rich biodiversity offshore, including large numbers of juvenile blue sharks, Prionace glauca. Species richness and abundance in the deep sea is positively related to hard rocky substrate and biogenic habitats such as sea pens, crinoids, whip corals, and gorgonians were present at 40% of the deep camera deployments. We observed distinct differences in the deep fish community above and below ~750 m depth. Concurrent oceanographic sampling showed a discontinuity in temperature and salinity at this depth. While currently healthy, Tristan’s marine ecosystem is not without potential threats: shipping traffic leading to wrecks and species introductions, pressure to increase fishing effort beyond sustainable levels and the impacts of climate change all could potentially increase in the coming years. The United Kingdom has committed to protection of marine environments across the UKOTs, including Tristan da Cunha and these results can be used to inform future management decisions as well as provide a baseline against which future monitoring can be based.

Tuna Regional Fisheries Management Organizations (RFMOs) are responsible for conservation and sustainable management of transboundary tuna resources in Exclusive Economic Zones and Areas Beyond National Jurisdiction (ABNJ). The data collected and analyses performed by tuna RFMOs are one of the main sources of scientific information supporting the management, sustainable use and conservation of biodiversity in the ABNJ. An understanding of the scope and availability of data provided by tuna RFMOs is timely, given the expected establishment of a new legally binding high seas agreement to protect marine biodiversity in the ABNJ. We examined official catch statistics and stock assessments that are accessible in the public domain for the five tuna RFMOs, and evaluated their taxonomic, spatial and temporal resolution. We found that the Atlantic and Indian Ocean tuna RFMOs report catches for a greater number of taxa compared to Pacific RFMOs. There are substantial gaps in the taxonomic resolution of sharks and rays and ‘other teleosts’, and only about half of the reported global catches are georeferenced, despite existing mandatory requirements. Additionally, the estimation and reporting of discards in all tuna RFMOs remains incomplete. Tuna RFMOs have made progress in implementing stock assessments for a wide range of taxa including targeted species with high economic value but also functionally important non‐target species with lower economic value. However, assessments should be expanded to cover other bycatch species. We emphasize the importance of accessible and accurate statistics, for supporting the research and societal oversight needed under any future ABNJ biodiversity treaty.

Here we describe the first underwater sighting of Shepherd's beaked whale (Tasmacetus shepherdi). Two individuals were observed together on video footage obtained via mid-water stereo-Baited Remote Underwater Video Systems (BRUVS) deployed off the coast of Inaccessible Island, Tristan da Cunha, in the South Atlantic. This observation constitutes the first recorded live sighting of this species in the waters of Tristan da Cunha since 2002 and provides further evidence for the persistence of a population of this species in the region. The observed individuals lacked the dark flipper stripe observed in previous descriptions, indicating that the species may exhibit greater variation in pigmentation than previous records indicate. The planned implementation of a marine reserve in the region along with the current low level of fishing pressure and remote location of this archipelago provide a good context to ensure the appropriate management and protection of this rare species. The recent establishment of an ongoing mid-water stereo-BRUVS monitoring programme, in concert with other methods targeted at marine mammals, may yield further information about this little known species and aid in informing management decisions in the future.