A fishing weir, fish weir, fishgarth or kiddle is an obstruction placed in tidal waters, or wholly or partially across a river, to direct the passage of, or trap fish. A weir may be used to trap marine fish in the intertidal zone as the tide recedes, fish such as salmon as they attempt to swim upstream to breed in a river, or eels as they migrate downstream. Alternatively, fish weirs can be used to channel fish to a particular location, such as to a fish ladder. Weirs were traditionally built from wood or stones. The use of fishing weirs as fish traps probably dates back prior to the emergence of modern humans, and have since been used by many societies around the world. History The English word 'weir' comes from the Anglo-Saxon wer, one meaning of which is a device to trap fish. A line of stones dating to the Acheulean in Kenya may have been a stone tidal weir in a prehistoric lake, which if true would make this technology older than modern humans. In Ireland, fish traps in association with weirs have been found that date from 8,000 years ago. Stone tidal weirs were used around the world and by 1707, 160 such structures, some of which reached 360 metres in length, were in use along the coast of the Shimabara Peninsula of Japan. In medieval Europe, large fishing weir structures were constructed from wood posts and wattle fences. V-shaped structures in rivers could be as long as and worked by directing fish towards fish traps or nets. Such weirs were frequently the cause of disputes between various classes of river users and tenants of neighbouring land. Basket weir fish traps are shown in medieval illustrations and surviving examples have been found. Basket weirs are about long and comprise two wicker cones, one inside the other—easy for fish to get into but difficult to escape. In September 2014 researchers from University of Victoria investigated what may turn out to be a 14,000-year-old fish weir in of water off the coast of Haida Gwaii, British Columbia. Great Britain In Great Britain the traditional form was one or more rock weirs constructed in tidal races or on a sandy beach, with a small gap that could be blocked by wattle fences when the tide turned to flow out again. Wales Surviving examples, but no longer in use, can be