Strategic approach to identify areas for spatial protection using pelagic ecoregionalisation in the subantarctic Indian High Seas

The PHOCIS project (Pelagic High Seas Ocean eCoregionalisation of the Indian Subantarctic) held an in-person workshop in Cape Town, South Africa between 25 - 29 August 2025 to discuss how the systematic conservation planning (SCP) process will be applied to the pelagic Indian subantarctic ocean to define a representative system of Marine Protected Areas (MPAs). The workshop participants included experts in oceanography, ecology, governance and conservation management as well as representatives from South African and French government institutions. Throughout the workshop, the participants were invited to contribute their knowledge and expertise. Building off the previous ecoregionalisation efforts of PHOCIS, there is now an in-depth understanding of the ecological, biophysical and biogeographical characteristics of the region as well as many spatial products that can inform a SCP process. The planning region of the SCP (20° - 150° E; 40° - 60° S) was determined and was informed by coherent ecological boundaries, processes and patterns. In order to guide the next steps of the SCP process, we have determined preliminary general and specific conservation objectives, informed by the CCAMLR conservation measure 91-04 article 2. During the workshop, participants developed a list of abiotic and biotic variables guided by the draft conservation objectives to inform the SCP process. Human activities were discussed as well as the potential impact of climate change and how this information will be used to inform the SCP process. An ecological synthesis of the PHOCIS study area and the first iteration of the spatial prioritization product of the SCP will be presented at WG-EMM 2026. The development of potential MPA in the subantarctic Indian has been informed since 2011 and responds to the CCAMLR willingness of developing a representative system of MPAs. The region is important to consider for conservation management as it faces major changes and will be a critical area that contributes to the representativeness of the MPA network within CCAMLR.