Geospatial analysis for sustainable aquaculture expansion: A case study on water spread area mapping and fish production potential in Dimbhe

Indian reservoirs with an area of 3.91 million hectares, possess immense potential for fisheries that offer economic and social security. Planning fisheries and aquaculture activities in a reservoir require knowledge of water spread dynamics and potential fish culture areas. Geospatial technologies in inland water resource management and decision-making have been widely used worldwide. The current study assessed the water spread dynamics and map potential areas for enclosed fish culture in Dimbhe reservoir, Maharashtra, India using Sentinel-2 Multi Spectral Instrument (MSI) images during the period 2019-22. Mapping of the spatial extent of the Water Spread Area (WSA) for identifying the potential sites and area for scientific ranching and fish culture using Normalized Difference Water Index (NDWI) and Water Presence Frequency (WPF) along with bathymetry was performed. The results showed that the WSA declines from Rabi season to summer season, with 70.44 percent (1445.39 ha) of the area covered with water for at least 8 months and 39.60 percent (812.45 ha) retaining water for at least 11 months, respectively. The calculated average number of fingerlings required to utilize the available water area in Dimbhe reservoir is 0.56 million with a production potential of 112.88 metric tonnes. The perennial WSA available in the Dimbhe reservoir is 551.22 ha which is most suitable for permanent cage culture practices. The study shall help in planning out scientific ranching and the improvement of enclosed fish culture locations with other water resource applications and to plan appropriate interventions for reducing the fish yield gap.