The effectiveness of local community in managing the dog conch (Strombus canarium Linnaeus, 1758) was evaluated in Sikao Bay, Thailand between 2007 and 2008. The dog conch densities were surveyed in two study sites under two management systems: community management and non-community management. After  that, the contour maps of the conch density were analyzed and demonstrated using GIS tool. The results revealed that low density of the conch appeared in non- community management area, whereas high density of the gastropod was recorded in the area that was managed by local organization. The higher density of the dog conch in the locally managed area indicated the effectiveness of community management in protecting mollusk resources. In that area, all destructive fishing activities were banned by the local people. Based on this finding, community-based management can be applied as a management tool to manage and conserve the dog conch in Thailand.