Analysing the spatiotemporal dynamics of coastal aquaculture along the northern coastal plains of Tamil Nadu, India, using remote sensing time series data

Aquaculture is one of the major and fastest emerging food production industries in India, globally ranking second only next to China in terms of total production. In recent decades, with the introduction of Penaeus monodon and Penaeus vannamei shrimp species, the coastal aquaculture in India has shown an exponential growth. The northern coastal plain of Tamil Nadu is one of the major hotspots for the shrimp aquaculture due to the favourable geomorphological and hydrological conditions. In this study, we used Sentinel-1 SAR time series satellite data and the manual extraction approach to map the spatiotemporal distribution of the coastal aquaculture ponds and validated with field visits. With the development of high spatial resolution baseline data of shrimp aquaculture, its distribution, density and hotspots were analysed at micro-administrative level. From the results, it is found that the coastal aquaculture ponds in the study area significantly increased between 2016 and 2024 by 634 ha with an annual change rate of 10.5% with major increase notably in the districts of Thiruvallur (44.4%), Cuddalore (26.4%) and Mayiladuthurai (13.2%). Spatial metrics including total aquaculture pond area (TAPA in %) and aquaculture pond density ratio show that intensity and distribution of aquaculture ponds were dominant in Thiruvallur and Nagapattinam districts. Hotspot analysis shows that the significant clusters of aquaculture concentration are confined near the tidal flats, estuarine zones and backwater networks. Our study contributes to micro-scale aquaculture monitoring by providing baseline information and underscores the importance of micro-level geospatial assessments in guiding sustainable aquaculture development, land use regulation and coastal resource management in vulnerable deltaic regions. This would enable the policymakers and governments in framing integrated coastal resource governance policies considering both environmental factors and human dimensions of aquaculture expansion.