Developing productivity and susceptibility attributes towards a rapid management-risk assessment of seaweed

The challenge of balancing conservation with sustainable use of marine resources faced by fisheries managers is quite often constrained by limited data on key species. This has become particularly true in the case of seaweed, which provide essential habitats for a diverse range of species in marine ecosystems and have long been valued by humans as food or, more recently, for their industrial applications. The expanding seaweed industry relies heavily on harvesting but historical declines in seaweed populations raise concerns over sustainability, leveraged by a general data-poor scenario for these species. To address this, we propose adapting the Productivity and Susceptibility Analysis (PSA) method—traditionally used in fishery assessments—for seaweeds. This novel approach incorporates the unique biology of seaweeds, including growth, reproduction, and susceptibility to environmental changes and harvesting practices, to evaluate their vulnerability. We applied this adapted PSA framework to a case study of seaweed harvesting in the Azores Archipelago, mid-north Atlantic, demonstrating its applicability in future science-based seaweed fisheries management srtategies. Among the 18 species studied, we identified five of high vulnerability ( Cystoseira pustulata , Fucus spiralis , Gongolaria abies-marina , Laminaria ochroleuca , and Ericaria selaginoides ). Our adapted PSA framework also considers local ecological impacts, stakeholder input, and relevant environmental factors, providing targeted management recommendations. While such a PSA does not replace stock assessments, it serves as a valuable risk assessment tool, identifying species needing greater management attention despite data limitations. Ultimately, this framework supports local, national and international policy and management measures, contributing to the conservation of coastal marine ecosystems. • Adaptation of the PSA method as a novel approach to assess seaweed vulnerability to harvesting. • Application of the adapted PSA method to assess seaweed harvesting in the Azores, identifying five highly vulnerable species. • Effective for data-poor species, serving as a valuable risk assessment tool.