Floods and Fish Migration; A Fishery's Response to Flood Management

Floods create aquatic habitat beyond the confines of river channels. This 'new' habitat is the source of floodplain productivity but continuation of the aquatic environment also serves as a link to connect rivers normally separated by land. These connections can be vital to migratory fish but can be lost when floods are managed.

The Waza-Logone floodplain or "Yaere" of the Logone River in northern Cameroon has high ecological and social importance. In 1979, the construction of the Maga Dam for rice production severely reduced river discharge and the area of inundated floodplain. In 1994, a reflooding programme and reinstated, albeit smaller, floods. Our Modeling Regime Shifts in the Logone (MORSL) group investigates the current dynamics of the floodplain fishery from a Coupled-Human and Natural Systems (CHANS) approach. 

Our work shows the current fishery has benefited from the reflooding programme, however, with significant differences. The pre-Maga Dam fishery targeted migratory Alestiidae spp. or the "African sardine" but the current catch composition is dominated by non-migratory fish. We propose the reduced flooding removed the migratory routes for juvenile Alestiidae and stimulated a sequence of events within the coupled-human system and help shaped the current fishery.