Spatio-temporal patterns and sustainable development of coastal aquaculture in Hainan Island, China: 30 Years of evidence from remote sensing

The fast-growing coastal aquaculture industry provides nutritious seafood and huge wealth for society, but also affects the natural environment and coastal ecosystems. There is an urgent need to realize the sustainable development of coastal aquaculture with regard to the trade-off between economic development and ecological conservation. Satellite remote sensing provides long-term data on the distribution and dynamics of aquaculture, which is essential for the design of suitable policy interventions for sustainable development. In this study, Landsat time series were used to map the tendencies and dynamics of aquaculture ponds for 30 years (1987–2018) in the coastal area of Hainan Island, China. The results showed that (1) the coastal aquaculture area of Hainan Island first increased rapidly, then increased slowly, and then decreased slightly in the past 30 years, increasing by approximately 10 times. The largest annual change rate of aquaculture ponds was between 2000 and 2005 (1597 ha/year), followed by the period 1995–2000 (1414 ha/year). (2) The development of aquaculture was unbalanced in the space, and Wenchang City in the northeast of Hainan Island accounted for 47.87% of the total aquaculture area in 2018. The aquaculture centroids moved from the center of Hainan Island to the northeast with a total migration distance of 72.9 km from 1987 to 2018. (3) There were three different types of development tendencies in the coastal cities (counties) (aquaculture areas increased continually; aquaculture areas increased first and then decreased slightly; aquaculture areas increased first, and then decreased significantly), mainly related to the different regional characteristics and development orientations. The different evolution phases of coastal aquaculture in Hainan Island were driven by relevant national and local government policies. Formulating and implementing appropriate aquaculture policies according to local conditions, as well as promoting industrial upgrading of aquaculture with high-tech, are significant suggestions for sustainable aquaculture. This study provides baseline data for local managers to assess the development of coastal aquaculture and reference experiences of sustainable aquaculture for other tropical islands and countries.