The Underwater Cultural Heritage of Stone Tidal Weirs

Tokyo University of Marine Science and Technology, Japan

Stone tidal weirs are a unique type of fish trap operated only by tidal amplitude. Stone tidal weirs are completely submerged during high tide when they trap fish. They emerge into full view at low tide, allowing people collect the fish. These pieces of maritime cultural heritage are found at various geographic locations around the globe and have prehistoric roots, but they are also intangible living heritage features. Many local coastal communities still actively use fishing weirs. These are located within seascapes created and maintained by the harmonious interactions of people within local marine ecosystems. In order to study, safeguard, understand and disseminate their importance appropriately to the broader academic community and public, we are working with local stakeholders who have a rich local traditional ecological knowledge, and employing anthropological theory or concepts to the analysis, rather than archaeological ones. The traditional ecological knowledge is not only the key to the conservation of stone tidal weirs but also for the well-being of communities – the seafood provided by fish weirs is more sustainable and healthier than imported canned or processed food. These days, the underwater cultural heritage of stone tidal weirs is vulnerable to the impacts of global climate change, such as sea level rise, coastal erosion, destructive storms, ocean acidification and marine plastic pollution. If sea levels rise more than one meter, all stone tidal weirs on the earth will not be able to function as they were designed. In this paper I address our current understanding of the functionality of stone tidal weirs, their importance within local communities and discuss some of the environmental threats to this ancient form of maritime heritage resulting from climate change.