Changing Coastal Commons in a Sub-Tropical Island Ecosystem, Yaeyama Islands, Japan - Island Futures: Conservation and Development Across the Asia-Pacific Region - page 131

Ebbing Tide Retreating Tide

Deep

TSW TSW

Shallow

Fish remain in the TSW

Ebb tide

Low tide

TSW

Feeding Offing

Fig. 10.2 The principle of tidal stone weirs in relation to fish movement patterns

towards the center which is deeper than the wing sides. In some cases, a TSW had
an entrance/exit in the central part. Fish coming from deeper waters through this
gate in ebbing tide are enclosed and shut in, and then later caught during low tide.
The gate is locally termed as futikakii (literally, mouth wall). In any event, fishers
can easily harvest fish around the central part of TSW by using a small gill net, four
diagonal net or hand net.
Tidal stone weirs were quite widely distributed throughout the Yaeyama Islands.
Before the Second World War, there were at least 23 TSWs reported on Ishigaki
(Editorial Committee of History of Ishigaki City 1994 ). Another source describes
tidal stone weirs at Kabira Bay, in Ishigaki, of 200-300 m in length (650-1,000 ft.),
with a height of 0.6-1 m (2-3 ft.) (History of Kabira Village Editorial Committee
1976 ). Another 27 TSWs have been counted on Kohama, of which six were still in
use in 1972 (Yano 2008 ) (Fig. 10.3 ). Evidence of the existence of other TSWs on
these and other islands in the Yaeyama group is available from other literary sources
(e.g. Editorial Committee of History of Shiraho Village 2009 ; Editorial Committee
of History of Ohama Village 2001 ; Editorial Committee of History of Ishigaki City
1999 ). Each TSW often carries its own particular name, the meaning of which is
mainly derived either from its geographical location or from its owner's kin-group
name (Yano 2008 ; Editorial Committee of History of Shiraho Village 2009 ).
It is evident that TSWs have played an important role in facilitating the provision
of regular fresh fish and other marine animal resources, especially as daily food for
the sustenance of coastal communities. More significantly, the first catch of the year
used to be offered to the community's sacred shrine ( utaki or ugan ). Fish were