Evolutionary pattern and influencing factors of the aquaculture development in the Guangdong-Hong Kong-Macao Greater Bay area during 1986–2020

The rapid expansion of aquaculture ponds at the end of the last century raised concerns about their environmental and ecological impacts in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). This study aims to comprehensively investigate the spatiotemporal evolutionary characteristics and explore the influencing factors of aquaculture development in the GBA. An automated approach was established to extract the aquaculture pond areas on the Google Earth Engine (GEE) platform using Landsat images and showed high accuracy. The aquaculture development in the GBA underwent three phases of rapid expansion (1986–1996), constant transformation (1996–2010), and drastic contraction (2010–2020), and was closely related to the important aquaculture policies in China and Guangdong Province. The local aquaculture ponds showed three evolutionary patterns of continuous shrinkage, earlier shrinkage, and later shrinkage, which were mainly influenced by the economic development level and urbanization in each city. Rapid urbanization created great demands for aquaculture products and intense land use competition, which drove the conversion of aquaculture ponds into impervious land and migration from the central GBA towards the surrounding coast and upstream areas. Government policies promoted the initial rapid increase and regulated the aquaculture ponds to develop towards a more environment-friendly and intensive mode, which led to a steady increase of aquaculture products despite the drastic decrease in aquaculture pond areas in the past decade. These evolutionary features are of significance for policymakers and farmers to maintain the sustainable development of aquaculture in the GBA and Guangdong Province.