Delivering effective marine protection on the high seas requires spatial frameworks that reflect pelagic ecosystem structure, dynamics, and climate sensitivity. The CCAMLR‑led initiative
PHOCIS—
Pelagic High Seas Ocean Ecoregionalisation of the Indian Subantarctic—provides a science‑based approach to determining pelagic ecoregions across large areas of the Indian Sector of the Southern Ocean's high seas. PHOCIS integrates physical oceanography, biogeochemistry, plankton, mesopelagic fish, seabirds, and marine mammals to identify distinct ecoregions shaped by ocean fronts and productivity gradients. PHOCIS supports ecosystem‑based management to inform conservation planning, including the identification of priority areas and representative pelagic habitats for consideration as Marine Protected Areas (MPAs).