From Infestation to Recovery: Evaluating Changes in Livelihoods and Fishing Productivity Following the Biocontrol of Kariba Weed Along Kyoga Basin Lakes and Kibimba Dam

ABSTRACT The invasive kariba weed ( Salvinia molesta ) has severely degraded aquatic ecosystems in Uganda's Kyoga basin lakes and Kibimba Dam, disrupting fisheries, navigation and community livelihoods. Between 2017 and 2021, the National Agricultural Research Organisation implemented a biological control program using the host‐specific weevil Cyrtobagous salviniae . This study assesses socio‐economic and ecological changes associated with the intervention using a quasi‐experimental before and after design combined with household fixed effects and variation in exposure duration. Household survey data were collected from 498 fishing households across Lake Kyoga basin lakes and Kibimba Dam between 2021 and 2022. Post‐intervention periods are associated with higher reported fishing productivity, with average fish catch per trip increasing by 42% and fishing income by 104% (based on regression estimate), alongside improved access to fishing grounds and reduced operational constraints. Respondents reported an 89% reduction in surface weed coverage and a 40% decline in health‐related challenges. However, increases in income were not consistently reflected in short‐term asset accumulation, highlighting constraints to translating ecological recovery into durable welfare gains. While the reliance on recall data for the pre‐intervention period limits strong causal inference, dose‐response patterns and robustness checks suggest that observed improvements are consistent with sustained bio‐control exposure. The findings indicate that biological control can play a critical role in restoring inland fisheries, but durable livelihood impacts require complementary investments in credit, extension services, and long‐term monitoring.