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.
Remains of a medieval fish weir just above the low water mark at Traeth Lligwy, Anglesey
Salmon weir at Quamichan Village on the Cowichan River, Vancouver Island, ca 1866
Algonquin fishing with weir and spears in a dugout canoe. After a drawing by colonist John White (1585).
The Martinsville Fish Dam Virginia, an historic Native American Indian fishing weir built with rocks
A fish trap is a trap used for catching fish and other aquatic animals of value. Fish traps include fishing weirs, cage traps, fish wheels and some fishing net rigs such as fyke nets.
Traditional fish traps, Hà Tây, Vietnam.
Cage trap at Lembeh Strait, Indonesia
Eel traps in England, 1899, by Myles Birket Foster
Fish trap, Roman period; found in Valkenburg, the Netherlands