Policy tool structures and innovation network evolution in China's marine ranching governance

Marine ranching has become an important approach for promoting sustainable fisheries and conserving marine ecosystems, yet its development is hindered by institutional and technological constraints. This study integrates social network analysis of 278 policy documents (2012-2024) with a structural assessment of 875 marine ranching-related patents to examine the evolution of China's policy tools and technological innovation networks. The results show that China's policy regime is highly centralized and disproportionately reliant on environment-type tools, leading to structural imbalance. Although technological innovation networks demonstrate increasing connectivity, they remain nascent, weakly integrated and geographically uneven. Notably, the Yangtze River Delta underperforms the Beijing-Tianjin-Hebei and Pearl River Delta regions despite its stronger foundations. These findings highlight the need to recalibrate policy mixes and strengthen multi-stakeholder innovation networks to support the coordinated and sustainable development of marine ranching.