Village-Based Giant Clam Protection Outperforms Federal No-Take Zones in American Sāmoa

American Sāmoa's coral reefs support populations of giant clams (Tridacna spp.), harvested for subsistence food and shell craft. Management of the resource is a patchwork: customary village-enforced closures known as fa'asao sit alongside federally designated no-take marine protected areas, national-park subsistence zones and locally regulated areas, administered separately by the territorial Department of Marine & Wildlife Resources (DMWR) and by federal agencies.

Researchers led by Paolo Marra-Biggs (Hawai'i Institute of Marine Biology) combined historical survey data from 1994/95, 2002 and 2018 with new transect surveys conducted 2022-2024 across six islands (Tutuila, Aunu'u, Ofu, Olosega, Ta'ū and Muliāva) — 194 new transects covering 2.32 hectares across 88 sites — comparing clam density and size across five management categories: village-protected areas, locally regulated areas, federal no-take zones, national-park subsistence areas, and remote/inaccessible sites.

On Tutuila, the only island where all five management types are present, clam density differed significantly by protection level (F(4,33)=10.3, p<0.001, eta squared=0.56). Mean clam size in village-protected and locally regulated areas averaged 17 cm, compared with 11.2 cm in federal no-take zones. The highest densities territory-wide (1,166 clams/ha) were recorded at remote, largely inaccessible Muliāva, underscoring that isolation from harvest pressure — not designation type alone — drives abundance.

The authors conclude that customary village enforcement, built on the fa'asao tradition of temporary closures, is at least as effective as, and on some metrics outperforms, federal no-take designation. They recommend that resource managers invest in supporting and monitoring traditional community stewardship rather than assuming top-down federal protection is inherently superior. American Sāmoa's Village Marine Protected Areas gained statutory backing in 2008 and, together with the DMWR's Community-Based Fisheries Management Program (est. 2000), covered roughly 25% of the territory's coral reef area by 2016.

Read the full analysis: https://peerj.com/articles/20290/

Read the full analysis: https://peerj.com/articles/20290/