The underwater cultural heritage of stone tidal weirs was originally born as a local fishing mechanism. The processes are based on a rich local traditional ecological knowledge, which brought on by members of local coastal communities. Traditionally, local communities used stone tidal weirs twice a month during the spring tide; a custom that has been preventing overfishing by locals. At high tide they sometimes functioned as fishponds. 

The traditional ecological knowledge, for instance, on non-fishing periods, as well as that on fishery-related ritual activities such as beach opening ceremonies, is widely observed at coastal communities but it is rapidly disappearing before being recorded properly by anthropologists or archaeologists. As stone tidal weirs are easily broken by typhoons or high waves, frequent community-led repairing works based on traditional knowledge are absolutely needed. In case stone tidal weirs are abandoned, however, both communal spirit and traditional ecological knowledge would extinct.  

The UNESCO UNITWIN Network for Underwater Archaeology and the ICOMOS International Committee on the Underwater Cultural Heritage (ICOMOS-ICUCH) act on the implementation of the UNESCO Convention on the Protection of the Underwater Cultural Heritage, which in its Article 1-1 defines ‘underwater cultural heritage’ as all traces of human existence having a cultural, historical or archaeological character which have been partially or totally under water, periodically or continuously, for at least 100 years. 

All stone tidal weirs are partially or totally under water during certain periods of time. Almost all stone tidal weirs, or at least their bases, all over the world are likely to have been constructed more than 100 years ago. This Convention is the first international law which acknowledges stone tidal weirs as cultural heritage that needs to be protected.  Many countries have not ratified it and there is the need to continue to raise awareness on the Convention.