Africa’s first ever dugong-tagging project has taken place off the coast of Mozambique, which conservationists believe will provide crucial data to help secure the future of the elusive, Critically Endangered marine mammals.
The ground-breaking initiative - a collaboration between wildlife NGO African Parks, Mozambique’s National Administration of Conservation Areas (ANAC) and James Cook University - saw seven male and four female dugongs in Bazaruto Archipelago National Park (BANP) fitted with specialised satellite-tracking tags.
Historically, the East African coastal subpopulation of dugongs (Dugong dugon) ranged from southern Somalia to southern Mozambique and were relatively abundant. But the number of mature individuals in the geographically-isolated East African coastal dugong subpopulation is now estimated to be fewer than 250, based on aerial surveys, including the Bazaruto seascape.
BANP is considered a refuge for East Africa’s last known viable population of dugong. Groups of dugong in Mozambique, Kenya, and Tanzania are small, usually just 1–10 animals, and rarely sighted.
“Dugong numbers have been severely depleted over the past few decades,” says Evan Trotzuk, African Parks’ Research and Monitoring Coordinator at Bazaruto.
“The Bazaruto subpopulation makes up at least 90% of East Africa’s remaining dugong population. The extinction of the dugong is probably inevitable in East Africa unless the loss of the Bazaruto subpopulation can be avoided.”
Dugongs, also known as sea cows, inhabit the tropical coastal waters of the Indian and western Pacific oceans. Their grazing habits promote the health of seagrass meadows, while they also contribute to genetic diversity by spreading seeds across meadows, which helps maintain healthy ecosystems that support many other marine species.
“Seagrass meadows are critically important in East Africa for fisheries, which provide economic livelihoods and food security for coastal communities, and for carbon sequestration,” explains Trotzuk.
“Dugongs are also historically culturally important in parts of East Africa, with unique myths and stories. The extinction of dugongs from East Africa would also mean the loss of this cultural heritage.”
Regular annual surveys undertaken by Bazaruto National Park over the past three years have indicated a stable population of a few hundred dugong, including an abundance of cow-calf pairs, which is a positive sign.
But the use of gill nets, which trap and drown marine megafauna, poses a critical threat to the dugong population. Seagrass coverage, on which the dugong rely entirely for food, has also shrunk by an estimated 20% in the tropical Indo-Pacific region over the past century.
“The principle threat is widespread unsustainable fishing practices, such as the use of gill nets that ensnare and drown dugongs,” says Trotzuk.
“While banned inside Bazaruto Archipelago National Park (BANP), gill nets are still used regularly in the north of the Bazaruto seascape. Seine nets also threaten dugongs as they destroy seagrass meadows and when left unattended can entangle and drown the mammals.
"The Bazaruto National Park management team has been working with local fishing communities to reduce the use of gill nets and improve the management of seine netting. Another threat is the loss of crucial habitats such as seagrass meadows due to coastal development, pollution, and direct damage.
"Without sufficient forage, dugongs, like all animals, will endure unfavourable conditions that could decrease reproductive rates and increase mortality rates.”
The tagging project is the next step in BANP’s dugong conservation efforts, after African Parks spearheaded the relisting of East Africa’s dugong population from Vulnerable to Critically Endangered on the IUCN Red List in 2022.
Experts from James Cook University provided technical support and training to local staff and scientists on the tagging process. “Attaching the tracking devices required lots of planning and careful preparation,” Trotzuk says.
"Weather, tides and chance all played their part. The tagging process itself is challenging. It’s not possible to sedate a dugong, as you might with terrestrial animals, nor to attach a tag from afar, like suction tags with whales. All tagging must be done while the dugong is fully conscious, which requires careful monitoring of key health indicators to prevent overstressing the animal.
"The Bazaruto team was fortunate to learn from the expert team at James Cook University and this transfer of skills will be vitally important for the future - nine of the park’s locally employed staff were trained to carry out the capture, tagging and sampling of dugongs.”
“The tagging operation was difficult in the beginning, especially because of the language differences for some people on the team,” adds Lorena Matos, Assistant Research and Monitoring Coordinator for African Parks.
“After the third dugong was tagged, we were more prepared and comfortable with the process. It was a great experience, and we’re proud to say that the Bazaruto team can fit tracking devices to dugongs - a first in Africa.”
The satellite tags will provide detailed information on the dugongs’ range, migration patterns, and feeding grounds. Dugong are capable of travelling hundreds of kilometres. They’re known to move out of the Marine Protected Area (MPA) into areas where risks are significantly higher.
The data will be instrumental in shaping effective conservation measures. “Mozambique aims to gazette 10-12% of its marine territory as conservation areas over the next few years - only around 2% is currently protected,” explains Trotzuk. “This tagging will help inform conservation planning initiatives by identifying key hotspots and movement corridors outside of BANP that deserve special attention. But there is still much work to be done. Since dugong movements are predominantly individualistic, it’s essential that at least 10% of Bazaruto’s dugong population count is tagged in order to get a comprehensive understanding of how dugongs move in and around their last refuge in East Africa.”
Main image: Scientists tag a dugong in Bazaruto Archipelago National Park, Mozambique. Credit: Andy Coetzee
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