Larval Fish Assemblages and Recruitment Dynamics in the Littoral Zone of Lake Volta: Implications for Transboundary Fisheries Management

Lake Volta is shared between Ghana and the northern extension of Nigeria's transboundary water systems, and its larval fish recruitment dynamics have implications for fisheries productivity on both sides of the border. This study investigated larval fish assemblage structure, temporal dynamics, and environmental drivers of larval abundance in the littoral zone of Lake Volta's northern basin, with comparisons to available data from the Nigerian Kainji Lake system to develop transboundary fisheries insights. Larval fish were collected using conical ichthyoplankton nets at six littoral stations twice monthly over 14 months. Specimens were identified to family level where possible and to genus or species for dominant taxa. Environmental variables including temperature, dissolved oxygen, transparency, and wind speed were recorded concurrently. Larval abundance showed pronounced seasonal peaks corresponding to the post-spawn aggregation periods of dominant cichlid and mormyrid species. Ciclid larvae (mainly Oreochromis spp.) dominated assemblages for six of the fourteen survey months. Mortality curves computed from length-frequency data indicated high early life mortality rates across all taxa, with estimated daily mortality coefficients of 0.14 to 0.28 per day. Water temperature was the strongest predictor of larval density in generalised additive models. Recruitment failure events associated with anomalous temperature drops were documented on two occasions. Comparison with Kainji recruitment data suggested synchronous recruitment cycles driven by shared macro-climatic forcing. The study recommends establishment of a transboundary monitoring consortium for larval fish dynamics. Keywords: larval fish, recruitment dynamics, Lake Volta, littoral zone, transboundary fisheries.