Assessing the Depletion Status and Sustainability of Catfish ( Clarias gariepinus ) Fisheries in the Southeast Arm of Lake Malawi

Catfish is a major commercial and subsistence species in Malawi, making its sustainability vital for local livelihoods and food security. However, limited evidence exists on the long-term biological and economic depletion of commercial catfish stocks. This study assessed the depletion status of the catfish fishery in the southeast arm of Lake Malawi using secondary catch and effort data from 2000 to 2023 obtained from the Malawi Department of Fisheries, and price and cost data obtained from the field study. Applying the bioeconomic Gordon–Schaefer model, the study estimated biological depletion and economic depreciation to quantify resource losses and evaluate the fishery’s sustainability. Constant and periodic harvesting strategies were examined to determine sustainable harvest thresholds. Results show that depletion occurred in 15 of the 24 years analysed, with a cumulative biomass loss of 446.1 tonnes and an estimated total depreciation of about MK 1.5 billion. These findings indicate exploitation beyond sustainable levels both biologically and economically, threatening stock recovery, long-term productivity, and economic viability. The study highlights the value of bioeconomic modelling in fishery assessment and underscores the urgent need for improved management, including strengthened monitoring, effort regulation, and enhanced enforcement, to ensure sustainable utilisation of catfish resources and protect dependent livelihoods.