Current status environmental stressors and management constraints affecting fisheries in lake Hashenge, Northern Ethiopia

Small inland lakes provide important fishery resources and ecosystem services but are increasingly threatened by environmental degradation and climate variability. Lake Hashenge, a closed high-altitude lake in northern Ethiopia, has experienced recurrent fish mortality events and substantial catchment modification. This review synthesizes published and unpublished information on the lake’s environmental condition, fisheries development, and socio-economic importance. Historical records indicate that the lake was stocked with fish species, including Nile tilapia ( Oreochromis niloticus ) and common carp ( Cyprinus carpio ), during the early 1980s. Although the potential fish yield has been estimated at 106–161.76 t year⁻¹, reported catches have generally remained below 25–30 t year⁻¹. Major fish mortality events, particularly in 2000 and 2014, have been associated with low dissolved oxygen conditions that may have been linked to lake stratification and turnover processes. Catchment degradation resulting from deforestation, overgrazing, and agricultural expansion has likely increased sediment and nutrient inputs, contributing to eutrophication, reduced lake depth, algal blooms, and declining water quality. The review identified four major stressors affecting the fishery and ecosystem: eutrophication and hypoxia, sedimentation and habitat degradation, the dominance of introduced common carp and its potential ecological implications, and climate-related hydrological variability. Additional pressures include wetland disturbance, improper waste disposal, and limitations in fisheries management and governance. Despite these challenges, Lake Hashenge remains an important source of food, income, and livelihood opportunities for local communities. Available evidence indicates that reported fish catches remain substantially below estimated production potential, while the long-term sustainability of the fishery is influenced by interacting environmental and institutional pressures. Integrated catchment management, strengthened fisheries governance, and adaptive management strategies are needed to support ecosystem conservation and sustainable fish production.