Spatiotemporal fish dynamics in Lake Malombe

Lake Malombe in Malawi has been under severe fishing pressure despite its continued provision of significant ecosystem services to the surrounding communities. Despite several research interests, there is limited up-to-date knowledge on the status of fish catch rates, diversity and biomass; hence, a study was conducted to assess the status of the fish stocks of Lake Malombe. The study specifically determined catch rates, fish species diversity, size distribution and biomass. It hypothesized that fish catch rates, species diversity, size and biomass were the same between the 2017 and 2025 surveys. Secondary data from the 2017 biomass survey was accessed at Monkey Bay Capture Fisheries Centre. Multiple data analysis tools were used in conducting statistical analyses for both 2017 and 2025 data. The current survey results registered a significant decline in the fish catch rates between the 2017 and 2025 surveys (p=0.0007). There was a significant decline in fish biomass of key fish species between the survey periods. Both surveys revealed relatively low fish diversity and evenness with no differences between the periods (p=0.085). Across the two surveys, the 54 identified fish species belonged to various conservation statuses. Changes in fish populations, including the decline of historically dominant species and the rise of smaller haplochromines, may reflect the impacts of overfishing and habitat damage to the ecosystem. Interventions that promote resource users are strongly recommended, such as better regulation enforcement, community-based co-management approach and habitat rehabilitation, so that the long-term restoration and conservation of fisheries resources in Lake Malombe can be achieved.