Pond aquaculture dynamics in Asia: Satellite time series for analyzing the spatio-temporal development of coastal aquaculture

Abstract

Asia plays a dominant role in global aquaculture, contributing over 88 % of the total aquaculture output, primarily through pond aquaculture systems used for the farming of fish, shrimp, and mussels. Coastal regions in Asia have experienced rapid spatial expansion of pond aquaculture. Recognizing the importance of spatial data in effectively monitoring and managing these systems, we present a methodological approach utilizing dense optical satellite time series archive data to analyze the spatio-temporal development of coastal pond aquaculture in Asia. This study builds on previous work that delineated all aquaculture ponds at a single-pond level for the entire coastal zone using a multi-sensor Earth Observation approach, integrating both SAR and optical satellite data. The resulting continental-scale vector dataset of mapped aquaculture ponds served as reference to derive spatio-temporal dynamics of coastal aquaculture. By utilizing multi-decadal Landsat archive data (1984–2019), we developed a framework to determine the annual status of each pond based on water masks derived from satellite time series. The methodology was applied across 22 coastal countries in South Asia, East Asia and Southeast Asia to investigate the development patterns of pond aquaculture. Using the complete, continentalscale dataset on annual pond aquaculture status, this research conducted geostatistical analyses of growth rates and spatial expansion patterns across various administrative levels, including national and district scales. Growth dynamics were examined for each individual country at 5- and 10-year time intervals. Between the 1980s and 2019, coastal Asia experienced significant expansion of pond aquaculture in time and space, with China, Indonesia, India, Vietnam, and Thailand emerging as the largest contributors. In 1988, reference aquaculture ponds covered around 6500 km2, increasing to over 19,000 km2 in 2019, representing a more than three-fold increase. Among the examined countries, China maintained the largest pond aquaculture industry, accounting for 40.6 % of the total active pond area in 2019, followed by Indonesia (13 %) and India (11.2 %).