Key Species in the Eastern African Marine Ecoregion
Turtles
There are seven species of marine turtle worldwide, five of which occur in the Western Indian Ocean
(WIO). These species include the green, hawksbill, loggerhead, olive ridley and leatherback turtles.
Marine turtles are long-lived and slow to mature and are susceptible to human exploitation at all
stages of their life cycle. Globally, most turtle populations are depleted and some are already extinct
as a result of centuries of human exploitation for food, oil, leather and ornaments, as well as mortality
associated with incidental capture in the fishing industry, marine and land-based pollution and
disruption of feeding and nesting sites.
All five species found in the WIO feature on the IUCN Red List of Threatened
Species and are listed on Appendix I of CITES. In the WIO, various studies indicate that turtle
populations have continued to decline with a high human pressure index accounting for
approximately 85% of turtle mortalities and illegal take-offs in the form of poaching of turtle meat,
eggs and oil.
Within the WIO region, all five turtle species nest. The green turtle is the most widely distributed and
most abundant and nests in Kenya, Tanzania, Mozambique, South Africa, Madagascar, Seychelles,
Comoros and Mayotte.
For more detailed information please consult the following regional publication from which the above extract has been taken; The Status of Marine Turtles in the United Republic of Tanzania, East Africa. C. Muir (2005).
Dugong
Dugongs occur in shallow tropical and subtropical coastal and
island waters of the Indo-Pacific. They are threatened
worldwide due to loss and degradation of seagrass pastures,
fishing pressure, indigenous use and hunting, and coastal pollution
and are listed globally by IUCN as vulnerable to extinction. The
WIO region harbours an important remnant population of the
threatened dugong and in a recent UNEP/IUCN report on their
global status, extinction of the dugong in the WIO region was
considered inevitable without immediate and effective
conservation measures.
Between April 2003 and March 2004, 7 countries in the region -
Kenya, Tanzania, Mozambique, Madagascar, Seychelles, Comoros
and Mayotte/Reunion – gathered information on the status,
distribution and threats to dugongs and made recommendations
for research and conservation. Data were collected through a
review of existing literature, questionnaire surveys and
opportunistic sightings.
Historical data indicate that dugong populations have suffered a
steep decline in most countries since the 1960s. In Kenya, large
herds were reported in the 1950s and ‘60s and a 500-strong
group was seen in 1967. In Tanzania groups of up to 20-30 animals
were commonly seen in the Mafia – Rufiji area at this time. In
Madagascar and Mayotte fishers have witnessed a decline since
the early 1980s while in Mozambique the decline may have been
more recent, escalating since the end of the civil war in 1992.
Prior to this study, dugongs were thought to be extinct in
northern Tanzania and their status in the south of the country
was unknown. In the Comoros Archipelago, small
numbers were believed to
occur around
Moheli Island but no
data were available
for Grand Comoro,
Anjouan and Mayotte. Information
gathered during this survey have
confirmed the existence of dugongs
in Tanzania and Mayotte and
established the regional significance
of the Bazaruto Archipelago
(Mozambique) as an important
dugong habitat.
In the past, dugongs were hunted for their meat, a prized source
of protein. However, deliberate captures have declined over
recent decades due to waning populations and low capture rates.
The main contemporary threat is entanglement in inshore
artisanal gill and shark nets. Other fishing gears such as seine nets
and fence traps pose a lesser threat. Destructive illegal fishing
techniques (dynamite and poison) may also be threatening
dugongs in Tanzania and Kenya.
Unplanned coastal development, land clearance
and land-based pollution are believed to be impacting the condition and extent of seagrass habitats in all
countries, with the exception of Aldabra Atoll. Habitat
degradation and loss is also attributed to trawling (Kenya,
Tanzania & Mozambique) and cyclones (Mozambique and
Madagascar). In Mozambique and Mayotte, disturbance to
dugongs from boat traffic and tourism activities were also cited
as threats.
In all the countries cited in this report, dugongs are afforded
protection under international and / or national legislation.
However, most governments in the region have neither the
capacity nor the resources to control and monitor all activities in
the marine and coastal zone.
Recommended priority actions for dugong
conservation in the WIO region are to:
- Improve the level of protection for dugongs inside and outside
marine protected areas by: promoting co-management and coownership
of marine and coastal resources among all
stakeholders; strengthening or imposing measures to reduce
the mortality from threatening fishing gears / techniques and
considering the provision of incentives and alternative fishing
gears; establishing dugong sanctuaries or community-protected
areas in sites currently unprotected and unmanaged; and
promoting trans-boundary conservation partnerships.
- Adopt the dugong as a regional flagship species and initiate a
region-wide public awareness campaign.
- Strengthen capacity of relevant government authorities to
enforce legislation.
- Determine and monitor dugong population characteristics
(status, distribution, movements) & habitat through quantitative
aerial surveys, catch monitoring and tagging, and assessments of
seagrass distribution, health and diversity; and
- Establish a regional network for dugong and general
conservation practitioners and researchers through the
existing Sirenian list server and promotion of national dugong
conservation task forces to facilitate the development and
implementation of dugong action plans and conservation
strategies.
For more detailed information please consult the following regional publication from which the above extract has been taken; The Eastern African Marine Ecoregion: Towards a Western Indian Ocean Dugong Conservation Strategy: The Status of Dugongs in the Western Indian Ocean and Priority Conservation Actions.
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Dolphins in Tanzania
The most common resident dolphins in Tanzania and Zanzibar archipelagos are bottlenose (Tursiops aduncus) and the humpback (Sousa chinensis). These two types are abundant in Menai Bay - in the South coast of Zanzibar. Marine Researchers have estimated that about 140 bottlenose and 60 humpback are resident at Menai Bay. Spinner dolphins (Stenella longirostris) are common at Nungwi and Matemwe off the north coast of Zanzibar. The Risso’s dolphins (Grampus griseus), humpback whales (Megaptera novaeangliae) and rough-toothed dolphin (Steno bredanensis) have also been observed in coastal waters off mainland Tanzania, Unguja and Pemba Islands. Other places where dolphins have been frequently sited or caught as by catch are Rufiji, Sadan, Kilwa, Tanga and Mtwara. The 400 individuals that were found dead in April 2006 at Nungwi Bay in Zanzibar were not residents of Tanzania / Zanzibar archipelagos. They are believed to have belonged to the Indo-Pacific bottlenose populations that live in deep offshore waters.
Dolphins of Menai Bay have attracted tourism that forms one of the main stay of the economy of Zanzibar. Villagers at Kizimkazi – Dimbani and Kizimkazi Mkunguni acknowledge that dolphin based tourism is among the dependable sources of income. The Menai Bay Conservation Authority (MBCA) is entitled to 100% retention of the royalties from tourism. An average of 3 US$ from every non-resident visitor and 1,000 Tanzanian Shillings from every resident visitor are set aside for supporting community development activities in the area. Dolphin based tourism has also created jobs for youths that operate boats or work in hotels.
Deliberate killing, incidental catch in fisheries (particularly drift, bottom-set gillnets and purse seine nets), habitat degradation, noise disturbance, pollution as well as unsympathetic tourism are the main threats faced by dolphin populations. A survey conducted by researchers at the Institute of Marine Science in Zanzibar from 1995 - 1999 revealed that 45% of all dolphins caught incidentally in fisheries in Zanzibar comprises of bottlenose dolphins, 30% spinner dolphins, 20% other unidentified species and 5% humpback dolphins. However, observations indicate that by-catch levels have decreased significantly following establishment of Menai Bay Conservation Authority.
For more information contact click here to visit the website of WWF International.
Whale sharks
Whale sharks (Rhincodon typus) are the largest fish in the world and occur in all tropical and warm temperate seas, oceans and coastal areas around the globe. Throughout most of their global distribution whale sharks have become threatened in the past 10-20 years because of the high commercial value of their large dorsal fins. In 2000 they were listed as Vulnerable on the IUCN Red List of Threatened Species, and in 2004 they were included in CITES Appendix II (which restricts international trade in whale shark products).
At least one population of whale sharks have found a local haven around the boundary of Mafia Island Marine Park, off the central Tanzanian coast one of the globally important Seascape areas. Despite the fact that there is routine trading of fins of other shark species from Tanzanian waters, whale sharks are not targeted by fishers in the area. Local fishers report that whale sharks only started appearing off Mafia during the late 1980s and have slowly increased in number ever since. The sharks migrate over a wide (but currently unknown) range, their peak presence in Mafia being between October-April. It is estimated there were about 30 different sharks in the area during the 2005/06 season.
WWF’s initiative on whale sharks at Mafia Island, Tanzania is an activity under the species and habitats protection component of the broader Rufiji-Mafia-Kilwa Seascape Program. The program aims to promote sustainable use of marine and coastal resources and to protect important biodiversity, endangered species and habitats within areas recognised as Tanzania’s high-priority coastal and marine seascape. The immediate aim of the whale shark work is to develop a better understanding of the local whale shark population dynamics, including distribution and migration behavior, number of individuals and gender, breeding behavior etc. This will be achieved through a tagging (using real-time satellite and archive tags) and observation programme.
At the same time, WWF supports the newly formed Mafia Island Whale Shark Association (of which WWF is a member) to develop protocols for tourism viewing and monitoring of the sharks, whilst also raising awareness amongst local Mafia people on the relative benefits of protecting the whale sharks as a source of tourism revenue.
For more information contact click here to visit the website of WWF international.
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