To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

Abstract

For seven years, village-based recorders monitored fish catches and water levels in seven floodplainassociated lakes of the Lower Rufiji, Tanzania. The lakes differ in the number of days and volume of inflows from the river, and thus provide a natural experiment to explore the links between catch composition, income per hour of fishing (IPHF) and hydrological connectivity, and to analyse the response of the users. The fishers adapt their fishing mode and equipment to achieve a rather constant IPHF of between 0.2 and 0.8 US$/fisher/hour. In situations of low connectivity, during a series of drought years, the less well-connected lakes lost many species and became a virtual monoculture of Oreochromis urolepis. Only in one extreme case was average fish size significantly reduced, indicating a high fishing pressure. Catch was therefore highly resilient to shifts toward illegal, non-selective and active fishing techniques. Fish diversity and lake productivity were quickly re-established when the larger lakes reconnected. The potential impacts of changes in the flood hydrograph (through dams, increased abstraction or climate/land-use changes) are assessed, and management options discussed. La taille moyenne des poissons a été significativement réduite dans un seul cas extrême, montrant ainsi la forte résilience des captures au changement vers des engins de pêche illégaux et non sélectifs et aux techniques de pêche active. La diversité halieutique et la productivité des lacs sont rapidement restaurées quand les plus grands lacs se reconnectent. Les impacts potentiels de modifications de l'hydrogramme de crue (par des barrages, des prélèvements additionnels et des changements climatiques/changements de l'utilisation des sols) sont évalués et des options de gestion sont évoquées.

Appropriation des ressources « naturelles » et criminalisation des communautés paysannes

“…Cette invisibilité est flagrante dans la promotion des grands projets de développement dont le Rufiji est la cible. Bien que concurrents, ces projets manifestent tous la même absence de prise en compte de l'existence même de ces populations : un barrage hydroélectrique qui mettrait fin au régime de crue sans lequel les activités agricoles et halieutiques locales disparaissent (Hamerlynck et al 2011) ; l'attribution de milliers 39. L'impuissance des communautés locales résulte de leur méconnaissance des lois et de l'absence de moyens financiers pour les faire valoir.…”

Mosquito Net Use in an Artisanal East African Fishery

“…Mosquito nets are generally deployed in shallow water, dragged by two or more fishers to catch pelagic-neritic fish, molluscs and crustaceans (Srivastava et al 2002;Lopes & Gervasio 2003;Samoilys et al 2011;McLean et al 2014). It is commonly perceived that MNF is primarily undertaken by women and children (Jiddawi &Öhman 2002;Van der Elst 2003;Abbott & Campbell 2009;Hamerlynck et al 2011).…”

The Multiple Benefits of River–Floodplain Connectivity for People and Biodiversity

“…The Mekong River supports the largest freshwater fishery in the world and its productivity is derived from the extensive floodplains and lakes inundated by the annual flood pulse. In the Rufiji River (Tanzania), fish diversity and lake productivity were higher in the well-connected floodplain lakes than in those rarely connecting to the river (Hamerlynck et al, 2011). Because much of this harvest consists of small fish consumed whole, fish also provide a primary source of calcium and other micronutrients in a region with little access to dairy products (Coates et al, 2003).…”