Impacts and vulnerability of inland fisheries to climate change in the Ganga River system in India

Abstract

Climate change is evident in India as manifested by increased air temperatures, regional variation in themonsoon, frequent occurrence of droughts, and a regional increase in severe storm incidence in coastalstates of India. The impacts are evident for freshwater fisheries and fishers of the River Ganga and the waterbodies in its plains and deltaic areas. Analysis of time series data for 32 years from published literatureand from current investigations showed a 0.99◦C increase in the minimum water temperature recorded inthe upper stretch of River Ganga and 0.5 to 1.4◦C increases in aquaculture water on the Gangetic Plainsof West Bengal. The minimum air temperature showed a 15% shift upwards during the colder months ofJanuary–February. Rainfall showed a 1% increase in the post monsoon months of September–December.The impacts were manifest in a geographic shift of warm water fish species such asGlossogobius giuris,Xenentodon cancilainto the colder stretch of the River Ganga. The breeding of the Indian Major Carps(IMC) has been affected and a consequent decline in fish spawn availability in River Ganga recorded.However a positive impact on breeding in fish farm hatcheries in the Gangetic Plains was evident in theadvancement and extension of the breeding period for IMC by 45–60 days. Drought in West Bengal during2009 was evident in rainfall deficits of 29% and 27% in the districts of North 24 Parganas and Bankura,respectively, in the fish breeding months of March–September and 92% of fish spawn hatcheries wereaffected. These districts recorded losses on average 61% to 73% of fish spawn during 2009 compared tothe previous four years. A study of the potential impact of cyclones and storms on saline water inundationusing a digital elevation model generated for coastal district of South 24 Parganas indicated the potentialfor 3% to 11% submergence of aquaculture areas in response to 1 to 2 meter rises due to sea waterincursions. The inland fisheries sector in coming years will face stiff competition for water from theindustrial, municipal and agricultural sectors and climate change will compound these problems. Undersuch a scenario implementation of integrated water resource management involving different stake holdersof fresh water would be the most effective management approach