The Expert Workshop on Pelagic Spatial Planning for the Eastern Sub-Antarctic Region (CCAMLR MPA Planning Areas 4, 5, and 6) held in Cape Town in 2019 aimed to develop a scientific work program for the regionalization of abiotic and biotic pelagic zones. The workshop emphasized the importance of plankton, mesopelagic fish, and top predators in understanding the sub-Antarctic region's ecoregionalization. This report is the preliminary work conducted to explore planktonic species presence over the area from 20°W to
160°E and from 30 to 60°S. The data were obtained from international databases and recent expeditions, and an analysis was performed to identify species assemblages using a biogeographic network approach. The results show the number of records and grid cells with the presence of major macrozooplankton taxa, focusing on euphausiids, amphipods and salps. The influence of the sampling method (Continuous Plankton Recorder or nets) can explain certain patterns of specific richness. The same concern applies to some offshore sectors as some of them have been heavily sampled using CPR, while others around the islands or in the subtropical Indian part have been sampled using nets. Further research and data cleaning will be necessary before moving on to the next step, which involves modelling the potential habitats of key keystone species in the pelagic ecosystem. Members of WG EMM are kindly asked to communicate if they have any additional surveys or occurrence data on the study area and if they wish to collaborate on this work.