Spatial and economic asymmetries in global sea-weed production and trade: Implications for coastal development and marine spatial planning

This study investigates the spatial and economic asymmetries in global seaweed production and trade between 2003 and 2023, highlighting implications for coastal development and marine spatial governance. Using harmonized datasets from FAO FishStatJ, FAO Seaweed Insights, and FAO trade circulars, triangulated with UNCTAD reports and peer-reviewed literature, we analyze six producer categories: China, Indonesia, Republic of Korea, the Philippines, Other Asia, and Rest of World. Three comparative indicators were computed: global production share, export value share, and export value-to-volume ratio (USD/ton), enabling diagnosis of structural disparities and functional upgrading trajectories within the global value chain (GVC). Results reveal extreme spatial concentration: Asia accounts for over 98% of global seaweed output, dominated by China and Indonesia. However, value capture remains disproportionately low for these biomass leaders, reflecting reliance on raw or minimally processed exports. In contrast, Korea and the Philippines achieve higher export intensity through product upgrading (nori and carrageenan derivatives), while Rest-of-World suppliers secure premium markets for agar and specialty extracts. These asymmetries confirm persistent “commodity traps” in major tropical producers and under-score governance challenges associated with volume-driven growth. The discussion links these disparities to coastal development pathways, emphasizing the need for integrated Marine Spatial Planning (MSP), ecosystem-based aquaculture (e.g., Integrated Multi-Trophic Aquaculture), and blue economy strategies that combine downstream processing, spatial zoning, and inclusive finance. Without such interventions, rapid aquaculture expansion risks ecological degradation and social inequality. Conversely, leveraging niche specialization and technological upgrading offers pathways to sustainable, equitable blue growth.