Les ressources halieutiques des lagunes ivoiriennes

Three main groups of species are exploited in the lagoons of Ivory Coast: a) Crustacea: 400 to 600 metric tons (m.t.) of the pink shrimp Penaeus duorarum , and 500 to 900 m.t. of bluecrab Callinectes latimanus are landed each year; b) Pelagic fish: amounting to about 7,500 m.t. Ethmalosa fimbriata representing the total landings and is found in all the lagoons. It is of low economic value. c) Demersal estuarine species: 1,500 to 2,500 m.t. of Cichlidae (Tilapia spp., Tylochromis sp.), Bagridae (Chrysichthys spp.), etc., are fished mostly in the oligohaline areas and these species are highly valuable economically. Some tonnage has decreased, i.e. shrimps and Ethlamosa in Ebrie Lagoon. This is because of two phenomena: Pollution damage of ecological conditions affecting mainly larval and post-larval stages of both species, and overfishing

Changes in the trophic structure, abundance and species diversity of exploited fish assemblages in the artisanal fisheries of the northern coast, Senegal, West Africa

International audienceThis work investigates the effects of changes in both fishing pressure and the environment on the trophic dynamics, abundance and diversity of species in the artisanal commercial fisheries off the northern coast of Senegal. Using artisanal commercial fishing data (provided by the Centre for Oceanographic Research of Dakar-Thiaroye [CRODT] in Senegal), we identify changes in the catch per unit effort, mean trophic level, biomass trophic spectrum and species diversity between two fishing periods (1990-1999 and 2000-2009). Decreases in mean trophic level, the biomass of high trophic level species and indices of species diversity between 1990 and 2009 were observed in commercial catches. These decreases were then related to changes in fishing pressure, fishing strategy and the combined effects of fishing and environmental factors (as derived from satellite observations). This paper helps to better inform the management of fisheries resources by providing decision makers with more effective biological indicators that incorporate the effects of fishing pressure and environmental change and that are applicable at local, regional and global scales

Analyse pluridisciplinaire de l’efficacité des Aires Marines Protégées, Le logiciel IPER : Estimation des Indicateurs de PERformance

National audienceno abstrac

A socio-ecological assessment aiming at improved forest resource management and sustainable ecotourism development in the mangroves of Tanbi Wetland National Park, The Gambia, West Africa

Although mangroves dominated by Avicennia germinans and Rhizophora mangle are extending over 6000 ha in the Tanbi Wetland National Park (TWNP) (The Gambia), their importance for local populations (both periurban and urban) is not well documented. For the first time, this study evaluates the different mangrove resources in and around Banjul (i.e. timber, non-timber, edible, and ethnomedicinal products) and their utilization patterns, including the possibility of ecotourism development. The questionnaire-based results have indicated that more than 80% of peri-urban population rely on mangroves for timber and non-timber products and consider them as very important for their livelihoods. However, at the same time, urban households demonstrate limited knowledge on mangrove species and their ecological/economic benefits. Among others, fishing (including the oyster-Crassostrea cf. gasar collection) and tourism are the major incomegenerating activities found in the TWNP. The age-old practices of agriculture in some parts of the TWNP are due to scarcity of land available for agriculture, increased family size, and alternative sources of income. The recent focus on ecotourism (i.e. boardwalk construction inside the mangroves near Banjul city) received a positive response from the local stakeholders (i.e. users, government, and non-government organizations), with their appropriate roles in sharing the revenue, rights, and responsibilities of this project. Though the guidelines for conservation and management of the TWNP seem to be compatible, the harmony between local people and sustainable resource utilization should be ascertained. copyright; Royal Swedish Academy of Sciences 2012.(IF52011 = 3.101; IF2011 = 2.025; CHL = 9.3).info:eu-repo/semantics/publishe