Assessment of the status of Chambo (Oreochromis species) and Other Shallow Water Fish Stocks in the Southwest Arm and Southeast Arm of Lake Malawi, Malawi

Abstract

Abstract There is overwhelming evidence that the shallow water stocks of Lake Malawi have been noticeably overexploited by both the artisanal and commercial trawl fishers. However, there have been some recent initiatives to restore these areas such as enhancing monitoring, control and surveillance, revamping local fisheries management authorities and establishments of community managed fish protected areas. Yet, information evaluating the impacts of such interventions on the fish stocks is limited. This information is critical for fisheries management and planning. Therefore, a study to reveal the current status of Chambo (Oreochromisspecies) and other shallow water fish stocks of the southwest arm (SWA) and southeast arm (SEA) of Lake Malawi was conducted. The study compared the status of fish stocks in the two arms using stock abundance and biodiversity indicators. Results indicated similar fish species diversity in the two arms. Overall, Chambo (Oreochromis spp.) was among the top ten fish that contributed a significant amount of weight to the total sampled catch. The SWA and SEA reported average catch rates of 77.4±22.6Kg/0.5hr and 177.7±18.4Kg/0.5hr, respectively whereas Chambo registered mean catch rates of 61.0±8.1Kg/0.5hr and 68.0±13.7Kg/0.5hr, respectively. Overall fish densities for all fish species in the SWA and SEA were estimated at 2.9tons/km2and 3.5tons/km2, respectively. Chambo density estimates for both SWA and SEA were calculated as 1.1tons/km2 and 1.2tons/km2, respectively. A total biomass of 10, 722 tons was estimated in both regions with the SEA contributing 57% while the biomass estimates of Chambo was 3,964 tons of which 54% was registered in the SEA. A decline in fish stocks in the shallow waters was observed and masks the efforts that the Government is doing to ensure the restoration and sustainability of fish stocks in the areas. It is therefore strongly believed thatregulating mesh sizes, limiting fishing effort and protecting critical breeding habitats are critical in reversing the observed trends.