In lieu of an abstract, here is a brief excerpt of the content:

9 Eastern African Dugongs Catharine E. Muir and Jeremy J. Kiszka The eastern coast of Africa marks the westernmost boundary of the dugongs’ global range. They are known to occur in the waters off Somalia, Kenya, Tanzania, and Mozambique (map 9.1). Their range also extends farther east off the islands of the Seychelles, Comoros, Mayotte, and Madagascar1. In Mauritius and Rodrigues dugongs were historically present, and in some places abundant, but declined during the eighteenth century due to hunting . Dugongs are now extinct in Mauritius2. The Western Indian Ocean (WIO) region is an important feeding and calving ground for dugongs as well as other endangered marine species such as sea turtles3. The region has a coastal population of more than 30 million people, who are among the poorest in the world and whose livelihoods are largely dependent on marine and coastal resources such as inshore fisheries and mangroves4 . The population is increasing at a rate of 5–6% per year and is expected to exceed 40 million by 2020. This rapid human expansion is having a significant negative impact on marine and coastal environments5. As in many areas of their range, dugongs here are severely depleted. Their future survival is threatened by incidental catch in fishing nets, habitat loss/degradation, fishing pressure, hunting, and pollution. Vessel strikes, acoustic pollution, and ecotourism pose lesser threats. Sharp population declines in recent decades have led to escalating concern about their future survival in a region where dugongs are considered to be critically endangered6 . This chapter explores the issues that influence dugong conservation in eastern Africa and presents a suite of possible conservation strategies in a region of rapid development. Dugong Status and Distribution The critical status of dugongs in eastern Africa and the lack of knowledge concerning their abundance and ecology were highlighted by Marsh et al.7, who called for immediate and effective conservation measures to ensure their future survival. This prompted an initiative to develop a regional WIO dugong conservation strategy8. As part of this study, in 2003, scientists from the seven countries in the region gathered data on dugong status, distribution, and threats, working mainly from historical data (literature reviews) and qualitative surveys (questionnaire surveys and opportunistic sightings). Since then, dugong studies and conservation programs have been set up in some countries, including Tanzania , Madagascar, the Comoros archipelago (Mayotte and Moheli), and Mozambique, to collect more data on dugong abundance, biology, and ecology as well as to raise awareness among local people. These studies indicate that populations are very small, isolated from one another, and threatened by gillnets and habitat disturbance. The mortality levels and the discrete nature of these populations underscore their critical conservation status. Mitigating the threats poses a major challenge for conservation managers, particularly as there are extensive gaps in knowledge of dugong biology, movements, population dynamics, and feeding, mating, and calving habitats. The summaries that follow for each country reflect the results from both the regional assessment and these national initiatives. Historical records and anecdotal reports indicate that dugongs were relatively abundant off the eastern African coast in the 1950s and 1960s, with herds ranging in size from 30 to over 500 individuals9. However, current information suggests that dugong populations have been declining sharply since the 1960s and 1970s in Kenya and Tanzania and more recently, since the late 1980s and early 1990s, in the Comoros, Mozambique, Madagascar, and Mayotte. In the Seychelles the historical status of dugongs is not clear. In southern Somalia dugongs are reported to occur around the Bajuni archipelago, but their current status is unknown10 (map 9.1). Kenya’s dugong population has dropped precipitously since the 1960s when large groups of animals were re- Eastern African Dugongs 85 ported, the largest a group of 500 seen in 196711. In 1994, ten dugongs were observed during an aerial survey12. During the last national aerial survey conducted in 1996, only nine dugongs were counted: six within the Lamu Archipelago in the north and three in the south near the border with Tanzania13. The most recent verified records are from the Tana Delta area, where two dugongs died in gillnets in September 200514. Based on recent research on the possible movement patterns of dugongs15, the extreme northerly and southerly populations may interact between southern Somalia and northern Tanzania. In Tanzania the most important dugong habitat is off the Rufiji Delta east to Mafia Island and south to Kilwa, an area characterized by extensive shallow seagrass beds and sheltered bays and channels. Dugongs have...

Share