Environmental and human factors affecting Indian major carps' spawning in Halda River, Bangladesh

The spawning success of Indian major carps (IMCs) in the Halda River is intricately linked to favorable environmental and hydrological conditions, which have shown significant variability in recent years. This research aimed to investigate the environmental and anthropogenic factors driving to decline in IMC spawning and propose sustainable management strategies. Field investigations were conducted across four key spawning sites, analyzing hydrological parameters, climatic trends, and anthropogenic influences. Results revealed a sharp decline in IMC spawning success in the year 2021, with egg production dropping to 8,580 kg and fry yield to 105.73 kg which reductions of 66% and 73.3%, respectively, compared to 2020. Key environmental stressors included rising temperatures (contributing 90% of observed variation), reduced rainfall (86%), decreased hill water runoff (84%), and saline intrusion (76%). Anthropogenic disturbances, such as pollution (76%), river bend cutting (80%), rubber dams’ installation (78%), and abandoned sluice gates (84%), intensified these challenges. This study reveals climatic and anthropogenic impacts on IMC spawning decline in the Halda River, stressing the need for ecosystem-based conservation. These findings underscore the urgent need for targeted mitigation measures, including minimizing anthropogenic disturbances and restoring natural river dynamics, to enhance the resilience of IMC spawning habitats and ensure sustainable fisheries in the Halda River.