The influence of flood regime on fish catch and fish communities of the Cross River Floodplain ecosystem, Nigeria

The morphology, climate and flood regime of the Cross River floodplain are summarized and related to the catch, species distribution and abundance of the economically important fishes of the floodplain ecosystem. Two flood indices, FI-1 and FI-2, are used to assess, statistically, the relationship between fish catch and flood regime. There are good positive correlations between the catch (C sub(T)) of year T and the flood index 1 of year T-1 and between (C sub(T)) and the sum of the flood indices 1 and 2 of year T-1 (r = 0.6516 and 0.6894, respectively, both at P = 0.05). Cross River is a relatively highly productive system (in terms of fish catch) and this productivity is attributable mainly to the yearly flooding of the plain when fish find allochthonous food materials in the expanded habitat. Changes in hydrometeorological conditions, such as the drought that affected the northern part of the Cross River basin in 1983-1984, if they persist can effectively reduce fish catch from the system.