The Madrid Protocol and beyond: Strategies for marine conservation in the high seas and Southern Ocean

The establishment of Marine Protected Areas (MPAs) on the high seas has recently emerged on the international agenda as a critical issue requiring the integration of novel approaches, international cooperation and political will. Since the high seas are subject to open access, the rights and obligations of States on the high seas can be ambiguous and confusing. There is a need to clarify how high seas marine conservation can be implemented under international law and in the Antarctic, both within and beyond the instruments of the Antarctic Treaty System (ATS). In recent years, Antarctic Treaty Consultative Parties have pondered the application of alternative international approaches and instruments in the region. This study seeks to contribute to this debate, assessing the ATS and key international instruments and approaches regarding their applicability to the high seas, comprehensiveness (assessed by species, in-situ or ex-situ conservation measures), progressiveness (application of the ecosystem or precautionary approach) and their legal status (soft or hard law, entry into force, Contracting Parties). Site selection for Southern Ocean MPAs is hindered by a lack of data on marine biodiversity. This study uses seabirds as surrogates for marine biodiversity. Drawing on a 20-year database comprising over 140,000 'at sea' seabird sightings, this study assesses the potential use of seabirds as surrogates for marine biodiversity in the Indian sector of the Southern Ocean. Surrogate indices used were species density, richness, IUCN status and Shannon-Weaver diversity. The seabird observations were aggregated into 1° (n = 1952), 2° (n = 704) and 5° bins (ri = 177). Surrogates were classified as high, medium or low, with 'high' areas of greatest conservation value. The study identified 22 urgent priority areas where conservation action appears justified, with clusters near Heard and McDonald Islands, and Isles Crozet. Integrating policy with science and considering area selection techniques provides an objective contribution to Antarctic conservation planning. Antarctic marine conservation is best managed within the ATS, with strong involvement from the Commission for the Conservation of Antarctic Marine Living Resources. The ATS could, however be strengthened by applying the principles and approaches used by key international instruments, particularly the Convention on Biological Diversity and the United Nations Convention on the Law of the Sea. The use of seabirds as surrogates has value in Antarctic conservation planning, but additional species or environmental data would improve the process.