Does the differentiated blue product structure affect country's blue economy status? Evidence from complex network and spatial econometric analysis

Upgrading the structure of blue products has become a key way to enhance the blue economy status of a country. An effective measurement of a country's blue economy status is necessary. Using traditional economy indicators alone does not fully provide a complete understanding of country's relative position in its trade relationships with others. In this study, the concept of country's blue economy status was transformed into an operational definition through complex network method. Considering the influence of the unavoidable spatial correlations between countries in blue product trade, the double-fixed spatial Durbin model was used to analyze the direct effect of blue product structure on the promotion of country's blue economy status and the spatial spillover effect on surrounding countries. The results showed that: (1) There is a significant spatial correlation between countries' blue economy status, meaning that countries are not randomly independent of each other and are also influenced by other regions. (2) Capacity accumulation, advanced, diversified, and rationalized blue product structure all contribute significantly to the uplift of country's blue economy status, but these four blue product structures differ greatly on the spatial spillover effect of surrounding areas. (3) The results of the heterogeneity analysis based on income level also answer questions in previous studies where consistent conclusions could not be reached due to differences in the subjects studied. This research provides a theoretical and empirical foundation for countries to implement differentiated blue product structure optimization policies based on their stage of blue economy development.