Relative abundance indices for critically endangered oceanic whitetip sharks (Carcharhinus longimanus) derived from pelagic Baited Remote Underwater Video Stations (pBRUVS)

Oceanic whitetip sharks ( Carcharhinus longimanus ) have undergone marked population declines due to overexploitation. Abundance trends typically rely on fisheries-dependent data that can be biased, particularly for protected species, as legal protections may influence compliance in capture reporting, likely leading to under- or inaccurate reporting. Fishery-independent methods offer complementary insights but traditional surveys (e.g., longlines) can be costly and difficult to implement. Here, we evaluated pelagic Baited Remote Underwater Video Stations (pBRUVS) to establish relative abundance indices for oceanic whitetips using both free-drifting and boat-tethered configurations. Across two sampling periods (April–May 2023 and 2024), we deployed 99 pBRUVS off of Cat Island, The Bahamas between Columbus Point (~ 24°07′ N, 75°17′ W), and Tartar Bank (~ 24°02′ N, 75°28′ W) where oceanic whitetips were detected on 51.52% of deployments. We used individual fin markings to estimate the minimum number of individuals per deployment (IND) and compared this to the common index MaxN (maximum individuals in a single frame). IND was positively correlated with, but typically higher than, MaxN—especially when MaxN exceeded one—and was up to three times greater where MaxN ≥ 2. In total, 50 individual oceanic whitetips were identified; 12 were resighted across deployments and 2 were resighted between years. pBRUVS also recorded other pelagic and semi-pelagic taxa (four additional shark species, twelve bony fishes, one cephalopod, and one sea turtle). Our findings demonstrate that pBRUVS support individual-level identification and robust relative abundance indices, providing a scalable, non-extractive approach to track oceanic whitetip population recovery.