Giant Clam Populations Flourish Under Indigenous Management in American Samoa

A new study led by researchers at the University of Hawaii Manoa Hawaii Institute of Marine Biology ToBo Lab has revealed that giant clam populations in American Samoa are far more stable and abundant than previously thought.

The research, published in the journal PeerJ, analyzed multi-decadal survey data and found that marine areas managed by local villages consistently support higher clam densities and larger clam sizes compared to federally designated no-take reserves.

Lead author Paolo Marra-Biggs stated that, contrary to expectations of decline, clam abundances have remained relatively stable over the past thirty years. The study highlighted that village-managed closures outperformed federally protected areas, showcasing the efficacy of cultural stewardship.

Senior author Robert Toonen pointed out that blanket federal restrictions may not be suitable for regions with effective Indigenous management systems. The research team conducted a territory-wide survey from 2022 to 2024, adding 264 new transects to historical surveys initiated in 1994.

This data set represents the most complete, multi-decadal compilation of giant clams for American Samoa, assessing population stability across six islands and various management zones. Marra-Biggs emphasized the importance of collaboration with local communities and agencies, stating that their work intersects science, culture, and conservation.

This joint effort supports Indigenous management and strengthens food security in the territory, with implications extending to Hawaii's efforts to revive traditional stewardship. The study is titled 'Status and trends of giant clam populations demonstrate the effectiveness of village-based protection in American Samoa' and was published in PeerJ in 2025.