<p>Norwegian salmon aquaculture, a cornerstone of the nation’s economy, faces significant socio-ecological challenges, including fish escapes, lice infestations, and environmental conflicts. This study explores how informal, self-organized networks contribute to sustainability within the sector, focusing on horizontal collaborations among salmon entrepreneurs and vertical collaborations between companies and municipalities. Drawing on 20 semi-structured interviews and policy document analysis from two regions in Northern Norway, the research highlights the role of adaptive co-management in fostering mutual learning, sustainability, and adaptability. Horizontal networks excel in knowledge sharing, trust-building, and collective action, enabling stakeholders to address biological risks, regulatory pressures, and economic challenges. Vertical networks, while more transactional, emphasize public–private collaboration, driving community and economic development through projects like property development and place-branding initiatives. However, vertical networks show limited engagement with environmental sustainability, often driven by external policies rather than shared long-term goals. The findings align with adaptive co-management principles, demonstrating the importance of trust, local knowledge, and iterative adaptation. Yet, regulatory constraints and relational dependencies pose challenges, particularly in fostering proactive environmental collaboration. This study underscores the complementary strengths of horizontal and vertical networks, offering insights into how informal governance systems can enhance resilience and sustainability in aquaculture. These findings have broader implications for resource-dependent industries navigating complex socio-ecological landscapes.</p>