Biological risk factors affecting fish growth and health in freshwater ecosystems of Inland fisheries of North 24 Parganas

Abstract

Freshwater inland fisheries of North 24 Parganas, West Bengal, India, represent a critical resource for rural livelihoods, food security, and regional economic development. However, the health and productivity of fish populations in this region face multifaceted biological threats that remain inadequately documented and scientifically evaluated. Through a systematic review of available literature, field survey data, and fisheries extension reports from the region, this study identifies Aeromonas hydrophila, Edwardsiella tarda, ectoparasites such as Argulus spp. and Dactylogyrus spp., and proliferating populations of introduced exotic species as primary biological stressors impacting native and cultivated fish species including Catla catla, Labeo rohita, Cirrhinus mrigala, Channa striata, and Mystus vittatus. The paper further analyses the interaction between biological risk factors and the prevailing environmental conditions of the Bidyadhari and Jamuna river systems, the Sundarban-fringe water bodies, and the numerous bheris (tidal ponds) and culture ponds spread across the district.Findings indicate that polyculture systems in the district suffer an estimated 15–30% annual production loss attributable to biological stressors, with disease outbreaks predominantly occurring during the monsoon and post-monsoon seasons. Strategic recommendations are provided for integrated disease management, biosecurity protocols, stocking density regulation, and genetic stock improvement to sustain and enhance the fisheries productivity of North 24 Parganas.