From fragmentation to coupling: exploring the evolution of China’s blue–digital product space based on trade-based product proximity

The growing interaction between digital technologies and marine industries has created new opportunities for blue economic development, yet their product-level relationships remain insufficiently understood. This study constructs a blue–digital product space to explore the long-term evolution of trade-based associations between blue and digital products in China from 1995 to 2024. Using international trade data, revealed comparative advantage (RCA), and product proximity, the analysis examines how the relationships between the two product groups changed over time. The results indicate that blue–digital product associations became broader and more diversified, with increasingly visible relationships involving technology-intensive marine products, particularly those related to marine equipment, shipbuilding, observation, and communication. Considerable heterogeneity is also observed across blue product categories. Rather than identifying a causal effect of digitalization on the blue economy, this study provides an exploratory and descriptive analysis of the long-term evolution of trade-based capability-related associations between blue and digital products. The findings provide a product-level perspective that complements existing macro-level studies of digitalization and marine economic development and offers a basis for future research using more direct measures of technological and industrial linkages.