General framework In fisheries there is a controversy as to whether fluctuating environmental conditions or heavy fishing are primarily responsible for fisheries collapses or changes. In Lake Tanganyika (catches estimated: 200 000 tons per year, 40 000 fishers, 1000 000 consumers) as in other great Lakes in East Africa, the abundance of some species has changed dramatically in the last 30 year. Attributing those changes to excessive fishing pressure is a too simple explanation that does not take natural variability and recent environmental changes into account. Ignoring natural cycles and true reasons for fisheries changes inevitably leads to management difficulties and lack of future development of the fisheries based on the hypothesis that the potential of the lake has been reached. However, a recent study (FAO/FINNIDA) has shown that the lake is actually overexploited only in very localized areas while the fluctuations of abundance of main stock of fishes could be linked to natural productivity cycles of the lake (Lindquist et al, 1999). The lake hydrodynamics is highly sensitive to climate (Naithani et al, 2002, 2003) and several significant correlations between fisheries catches abundance with local and global climate have been found (Plisnier,1997, 1998, 2000, O’reilly et al, 2003) as well as teleconnections between ENSO events and local climate and fisheries (Plisnier et al, 2000). Links between ENSO and fisheries suggest possibilities to forecast productivity of fisheries at Lake Tanganyika several months ahead of time. The main fisheries of Lake Tanganyika are based on two sardines fishes (Stolotrissa tanganicae and Limnothrissa miodon) and a perch (L. stappersi). Their relative abundance and behavior appear to be highly influenced by fluctuations of the environment. There seems to be extreme years in the Lake Tanganyika limnology. A highly dynamic environment appears to favor sardines fishes, particularly S. tanganicae, while stable conditions seem more favorable for L. stappersi abundance or catchability. There is little question today that there are natural fluctuations of great magnitude in fish populations which are attributable to causes other than fishing (Lasker, 1985). In Lake Tanganyika, since the last 20 -30 years climatic changes appear unfavorable to the upwelling in the south (a major hydrodynamic event linked to the productivity of the lake), the general turbulence level and internal waves amplitude in the lake. This probably caused the lake to be less dynamic. Less mixing of water is linked to a decrease of nutrients input from deep waters and a decreased in primary productivity (O’reilly et al, 2003). The project is investigating the relationships between climate and fisheries using an ecological model. This model could be developed with a fisheries component. Managers, could use climate data collected by their official network but also remote climate or proxy-climate data (El Nino) and input this in the model to simulate the level of the fisheries catches and species abundance in the next month or the next year. This information will be useful for all the stakeholders to make the best use of the resource without overexploiting it meeting a main concept of sustainable development. Specific tasks The objectives are to (1) investigate the impact of recent environmental changes on the fisheries of Lake Tanganyika using weather and limnological monitoring, fisheries statistics, remote sensing and eco-hydrodynamics modeling (2) use those results and the ECO-SLIM model under expected climate change most likely scenarios to evaluate the future of the fisheries at Lake Tanganyika (3) evaluate the feasibility of developing an operational ECO-FISH model as a forecasting tool for the managers of Lake Tanganyika fisheries.