Sierra Leone - State of the Marine Environment 2015

5. Species

A total of 29 species or species groups have been assessed (Fig. 5.1). On average biodiversity seems to be in good condition. Several groups show a declining trend over the past 5 years (e.g. inner shelf demersal and pelagic fish species, terns). Condition of other species or species groups seems to be stable. A discussion on the results is provided below. 5.1. Dolphins Little is known about the status of populations in Sierra Leone with the exception of sporadic sightings. The Atlantic Humpback dolphins ( Sousa teuszii ) frequently occur in the artisanal bycatch. Other cetaceans include the Clymene and common dolphins which are often sighted in deep waters beyond the 50 m isobar. According to results of the assessment, dolphin populations are in a very good condition. This is because they are not harvested. 5.2. West African Manatee ( Trichechus senegalensis ) A single representative of the Sirenean, the Africanmanatee ( Trichechus senegalensis ) occurs in river estuaries of Sierra

Leone. They frequently occur in the vicinity of the Ribbi River, Bonthe, Gbondapi etc. The assessment revealed that manatees are still in good condition. 5.3. Sharks and rays Sharks andrays areexploitedusingbottomsetnets respectively and their fishing efficiencies are subject to environmental variability. The artisanal fish landings for sharks appear to be at a peak in the dry season (March–April) and generally lower in rainy season (June–August). The reason for the apparent differences in seasonal shark landings has been attributed to the turbulence in the water column as a result of the ensuing tidal current caused by the rains. The situation would normally create difficulty in setting the net and hence undermine catchability and landings of shark species. The dominant ray species in shrimp trawl fisheries are Dasyatis pastinaca (44%) and D. margarita (23%). The shark species are dominated by Sphyrna lewini (72%) and Carcharhinus obscurus (15%). In the case of finfish demersal trawl fisheries, the dominant shark species are Carcharadon carcharias (44%), Carcharhinus brevipina (15%) and Sphyrna lewini (15%).

These stocks are under pressure from commercial trawlers.

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