• The Greater Pemba Channel

    LANDSCAPES

    The Greater Pemba Channel

    Tanzania’s extraordinary biodiversity extends beyond the land and into the marine realm. WCS’s marine conservation work currently focuses on whales, dolphins and other marine megafauna.
  • Research

    THE GREATER PEMBA CHANNEL

    Research

    WCS is carrying out a national assessment of whales and dolphins to provide baseline information on species, hotspots and threats throughout Tanzanian waters
  • Indian Ocean humpback dolphins

    THE GREATER PEMBA CHANNEL

    Indian Ocean humpback dolphins

    One of our priorities for conservation is the Indian Ocean humpback dolphin - Tanzania’s most endangered dolphin.
  • Humpback whales

    THE GREATER PEMBA CHANNEL

    Humpback whales

    WCS is carrying out research into humpback whale distribution, abundance, migratory routes, and resting areas as well as threat incidence.
  • Research

    THE GREATER PEMBA CHANNEL

    Research

    The WCS BigBlueTz Survey was a boat-based visual and acoustic survey of the cetaceans of Tanzania covering 2,600km along the entire Tanzanian coast, including the islands of Mafia, Zanzibar and Pemba.
  • Southern/ Highlands
  • Ruaha/ Katavi
  • Tarangire/ Ecosystem
  • Zanzibar/ Forests
  • Greater/ Pemba Channel

WCS’s marine conservation work currently focuses on marine mammals and includes carrying out a national assessment of whales and dolphins and research into the Indian Ocean (IO) humpback dolphin - Tanzania’s most endangered dolphin. Studies of Tanzania’s seasonal humpback whale population and threatened sharks and rays are beginning.

CONSERVATION SIGNIFICANCE CONSERVATION SIGNIFICANCE

There is very little information on which species of whales and dolphins occur and what threats they face in Tanzanian waters. WCS is gathering essential baseline data on marine mammal communities as a first step to identifying and prioritising species and locations that require urgent conservation action. The Pemba Channel has already been identified as an EBSA (Ecologically and Biologically Significant Area) and with its steep drops in bathymetry, rapid current and variety of habitat types it was identified by WCS as having amongst the highest cetacean densities in the country.  One either side of the deep Pemba Channel extensive shallows, reefs and mangroves support significant numbers of endangered IO humpback dolphins. The Greater Pemba Channel Seascape includes two marine parks, the Pemba Channel Conservation Area and the Tanga Coelacanth Marine Park, and a proposed trans-boundary marine area.

THREATS THREATS

Unsustainable fisheries and by-catch are the main threats to cetaceans in Tanzania - especially IO humpback dolphins which occur within 2km of shore and in water less than 15m deep. WCS work has shown that 40% of IO humpback dolphin’s small resident population around Pemba Island bear the scars from entanglement with fishing gear. In March and April 2015, WCS acoustic equipment recorded 318 underwater explosions from blast fishing along 2,700 km of the Tanzanian coast. The results show the scale of the problem, its geographical distribution and hotspots where environmental impacts are greatest.

WCS APPROACH WCS APPROACH

One of the largest marine initiatives conducted by the WCS Tanzania Program is the national assessment of whales and dolphins in Tanzanian coastal waters. This brought together information on cetaceans from a large number of sources including field visual and acoustic surveys, historical reports, information on skeletal remains, sightings from dive operators and tourists, and local knowledge. These data will enable the identification of sites of potential conservation priority for cetaceans requiring more study and protection. 

The WCS #BigBlueTz Survey was a boat-based visual and acoustic survey of the cetaceans of Tanzania covering 2,600km along the entire Tanzanian coast, including the islands of Mafia, Zanzibar and Pemba (which each have Marine Reserves). Sightings of 11 of Tanzania’s 18+ species were recorded, including Blainville’s beaked whales - a new species for the country. Spinner dolphins were sighted in groups of up to 800 and Risso’s, common bottlenose and Indo-pacific bottlenose dolphins were frequently seen. IO humpback dolphins were seen in shallow near-shore areas in the north of the country and seem rare or absent in the south. 

Research into the occurrence, habitat and threats to the IO humpback dolphin is a focus. WCS is collecting baseline data on the presence, distribution, range and abundance of this species, as well as researching the characteristics of its habitat and quantifying by-catch and hunting in the Greater Pemba Channel area. Furthermore, marine protected area (MPA) managers and staff on Pemba are being trained to better enable them to monitor and conserve cetaceans.

Photo-identification using dorsal fin scars is being used to understand the connectivity between areas of IO humpback dolphin concentration throughout East Africa. This research is to determine whether these species on Pemba Island are isolated (or if there is cross-border movement between Kenya and Tanzania), and to understand whether existing marine parks are sufficient to protect this endangered species. A bilateral ‘East African Cetacean Working Group’ has been set up to facilitate the sharing of data.

The acoustic techniques that are commonly used to record the vocalisations of cetaceans also record other sounds in the marine environment. The #BigBlueTz national cetacean assessment survey in 2015 provided a national overview of the nationwide distribution of fishing with explosives. Hotspots around Dar es Salaam, Tanga, Lindi and near Songo Songo will be further monitored in collaboration with government authorities to demonstrate whether law enforcement efforts have resulted in actual declines in the number of blasts.  

Humpback whales arrive in Tanzania each year in June-July and are present until October-November. Remarkably little is known about their migratory routes, numbers, behaviour patterns and preferred habitat. WCS has placed underwater acoustic recorders at key locations around Pemba and Unguja Islands in an effort to learn more. The recorders will operate from July to November 2016, and depending on conditions, can detect whales from 5 to 50km away. The data will also be examined to look for the presence of Blue Whales, Sperm Whales and Beaked Whales - all little known species in the region.