Impact of marine industrial agglomeration on the high-quality development of the marine economy——A case study of China's coastal areas

•Explored the impact mechanisms and interrelationships between industrial agglomeration and high-quality development in the marine sector.•Constructed a five-dimensional evaluation index system for high-quality development of marine economy.•The impact of industrial agglomeration on the green development dimension of the marine economy is time-lagged.•The impact of industrial agglomeration on high-quality economic development in the marine sector shows regional heterogeneity. Although the high-quality development of the marine economy has become a new paradigm to explore sustainable development in China, the path to its realization remains unclear. One path being explored in China is industrial agglomeration, but whether industry clustering leads to high-quality development of the marine economy has not been fully explored. Thus, the impact of industrial agglomeration on the marine economy deserves further investigation. This study first establishes a five-dimensional index system (innovation, coordination, greenness, openness, and inclusivity) to gauge the quality of marine economic development and then applies a hybrid method to evaluate each dimension. Furthermore, from an industry perspective, this study explores the influence mechanism of marine industry agglomeration on the high-quality development of China’s marine economy from several dimensions. The results show that (1) different regions have significantly different development levels, and the growth rates vary across each dimension. (2) From a broad standpoint, marine industry clustering has greatly promoted high-quality economic development in four sectors: innovation, coordination, openness, and inclusivity. However, its impact on green development has a time lag. (3) From the perspective of geographical heterogeneity, the impact of industry clustering is insignificant in the Bohai Rim region, positive in the South China Sea region, and negative in the Yellow Sea and East China Sea. Our study can enrich the research in this field and provide reference for the development of marine industry and marine economy in coastal areas.