Policy Pathways for Enabling Mussel Shell Reuse in Marine Restoration in Chile

Chile is the world’s second-largest producer of mussels and the leading exporter, harvesting approximately 400,000 t/year, of which about 30% becomes shell waste. While this biomaterial poses a growing disposal challenge, it also represents an opportunity for marine ecological restoration. In southern Chile, where mussel farming is concentrated, efforts to reuse shells as nature-based solutions (NbS) face legal and institutional constraints. This study examines the regulatory conditions shaping shell reuse through analysis of national, regional, and local legal and policy instruments, complemented by a participatory workshop with 50 stakeholders. Instruments were assessed across six policy domains and coded by legal function (enabling, restrictive, or ambiguous) and regulatory effects, identifying hard barriers, contextual friction, and underutilized enabling levers. Results show that although current regulations—particularly the classification of shells as waste—formally restrict marine reuse, key constraints extend beyond explicit prohibitions. Interpretive ambiguity, procedural uncertainty, and fragmented institutional mandates play a central role in limiting restoration initiatives. Workshop insights suggest that overcoming these barriers does not require comprehensive legal reform, but can be achieved through reinterpretation of existing rules, technical standard-setting, and improved inter-agency coordination, supported by pilot projects with strong legitimacy. These findings highlight that shell reuse is not only a legal and technical challenge, but also a cultural and ethical one, requiring approaches that integrate ecological goals with social legitimacy and community participation. The Chilean case illustrates how regulatory innovation can emerge within existing legal systems, offering transferable insights for advancing circular NbS in coastal governance contexts.