Ecological considerations for marine spatial management in deep-water Tanzania

The United Republic of Tanzania has jurisdiction over a large marine area (223,000 km2) of which over 92% is deeper than 200 m. These deep areas extend from, in most cases <10 km from shore, have connections to shallow and coastal marine habitats through oceanographic processes, and support important living and non-living resources, which are becoming increasingly exploited to support a valuable blue economy. Recognising the need for sustainable development, implementation of conservation and management measures in Tanzania's offshore waters has begun, with the development of coastal protected areas and marine spatial plans (e.g. the Coastal and Marine Spatial Plan for Zanzibar). As yet, the deeper areas of Tanzania have not been considered in marine spatial planning. Here we present a synthesis of available data on the habitats and biological communities of deep-water Tanzania, including new data collected in collaboration with the deep-water oil and gas industry, to provide an indication of regional-scale patterns and areas of potential importance. We also discuss the value and multiple uses of the deep ocean areas to Tanzania, and assess the ecological effects of impacts in these environments. This information is valuable to the Tanzanian government to help inform development of management measures to continue to make sustainable use of valuable deep-water resources. To facilitate uptake, we provide a series of recommendations on considering the Tanzanian deep ocean areas in marine spatial planning to boost future management of the important and sensitive offshore domain.