A dugong monitoring network was established in the Rufiji Delta in 2004, which was the last known refuge in Tanzania for this species. In 2009, a dugong was sighted on the west coast of Mafia Island and the network was extended to include Mafia. Members of the network, comprising Conservation Officers, local fishers and village leaders, record live dugong sightings and report dugong mortalities.
Since the establishment of the dugong monitoring network, 67 dugong sightings have been reported to Sea Sense. Of these, 53 were live sightings (including two mother/calf pairs), 14 had drowned in gill nets (including one mother/calf pair) and one was stranded on a beach. Even though sightings are rare, there is clear evidence that a small breeding population exists in the Rufiji Delta - Mafia Island seascape. There has been a steady increase in the number of reported dugong sightings since 2004, which can most likely be attributed to Sea Sense awareness and education programmes. The last live dugong sighting was in September 2021, when an individual was sighted on the west coast of Mafia Island.
Tissue samples were taken from nine of the stranded dugongs and sent to James Cook University in Australia for analysis. DNA was successfully extracted from four of the samples and compared to DNA from dugongs in the Arabian Gulf. The results suggest that there is little genetic variation in east African dugongs, and that they are genetically close to dugongs from the Arabian Gulf.
Between 2014 and 2018, a regional dugong research and conservation project was initiated, funded by the Western Indian Ocean Marine Science Association (WIOMSA). The project was a regional collaboration between Tanzania, Kenya and Mozambique and Sea Sense was the lead investigator in mainland Tanzania. The project aimed to re-evaluate the status of the east African dugong meta-population. All three countries conducted the same surveys using standardized protocols to allow comparisons between sites and countries. The overarching goal of the project was to provide data that could support an IUCN Red Listing at the sub-population level. Globally, dugongs are listed as Vulnerable, largely due to stable populations in Australia and the Arabian Gulf. However, east African dugongs are at high risk of local extinction, with Mozambique supporting the last viable population in the region.
Sea Sense has conducted seagrass habitat surveys in the Rufiji Delta and on the west coast of Mafia Island, where recent dugong sightings have been reported. Survey teams identified seven seagrass species and recorded dugong feeding trails at Mbarakumi Island and Bwejuu in Mafia and in Mohoro Bay in the Rufiji Delta. Prior to the surveys, dugong sightings and mortalities had been reported within the Rufiji– Mafia Seascape but the exact location of their feeding habitat was unknown.
In 2006 and 2008 Sea Sense conducted aerial surveys to assess the distribution and abundance of dugongs in the Rufiji Delta. A mother and calf were observed in seagrass meadows during one aerial survey but no other observations were made.
Sea Sense repeated the aerial surveys in 2016 and 2017 as part of the regional assessment. However, no dugongs were observed during either survey.