The Distribution and Abundance of Hammerhead Sharks (Family: Sphyrnidae) and Sawfishes (Family: Pristidae) within Malindi-Ungwana Bay in Coastal Kenya

1 Apr 2021 Malindi-Ungwana Bay, Kenya, Africa Fishes | Habitats | Marine

Lameck Joash Menya Otieno

1. To determine the species of hammerhead sharks (Family: Sphrynidae) and sawfishes (Family: Pristidae) landed by prawn trawlers in the Malindi-Ungwana Bay, Kenya.
2. To determine the seasonal catch rates (Kg/hr) of species of sawfishes and hammerheads landed as by-catch by prawn trawlers in the Malindi-Ungwana Bay, Kenya.
3. To spatially demarcate the areas of high catch rates of sawfish and hammerhead shark species within the bay and hence determine the conservation hot-spots in the bay.
4. To determine the size-structure, sex ratios and maturity status of the landed species of hammerhead sharks and sawfish species within the Malindi-Ungwana Bay, Kenya.
5. To publish and disseminate the results by way of a M.Sc. Thesis and Journal publications.

Hammerhead sharks are among the endangered shark species, while all the five known species of sawfishes are endangered or critically endangered with extinction according to IUCN redlist. The species are generally threatened by fishing pressure for their fins, meat or rostra. Additional threats come from trawlers that land them as by-catch or discards. Nonetheless, sharks play important roles in the ecosystem and information is needed for scientific management of their stocks. Hammerheads and sawfishes are particularly threatened with extinction globally, because of their life history traits and body structures.

By-catch by trawlers and other fisheries account for over 50% of sharks landed globally. Because sharks are not commercially valuable in many countries including Kenya, there are no management measures for stocks. However, management actions even where intended are hampered due to lack of scientific information on populations. In Kenya, shark and rays are captured in large numbers within the productive Malindi- Ungwana Bay on the north coast. They are landed as by-catch with significant discards by the prawn trawlers. However, there is lack of information on catch rates by the prawn trawlers and distribution of species within the bay. Among the sawfishes, no information exists on the species composition and their distribution within the bay, but catches are known to occur. The project therefore aims to work with the prawn trawlers in the bay in order to generate data on the seasonal catch rates of the species, size composition, spatial distribution, sex-ratios and maturity status of the hammerhead and sawfish species landed by the prawn trawlers in the Malindi_Ungwana Bay. Sampling will be done aboard prawn trawlers which land sharks as by-catch. Data to collect on the sharks will include monthly catch rates, size distribution, spatial distribution and species identification for hammerheads and sawfishes. Data will be analyzed for thesis dissertation and will also be disseminated for conservation and management purposes following the envisaged National Plan of Action for Sharks.