Ancient Monuments

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Llanddona Fish Weir

A Scheduled Monument in Llanddona, Isle of Anglesey (Ynys Môn)

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Latitude: 53.3082 / 53°18'29"N

Longitude: -4.144 / 4°8'38"W

OS Eastings: 257246

OS Northings: 381168

OS Grid: SH572811

Mapcode National: GBR JM4Y.NJ9

Mapcode Global: WH53V.93XQ

Entry Name: Llanddona Fish Weir

Scheduled Date: 31 October 2002

Source: Cadw

Source ID: 3906

Cadw Legacy ID: AN137

Schedule Class: Maritime

Category: Fish weir

Period: Post Medieval/Modern

County: Isle of Anglesey (Ynys Môn)

Community: Llanddona


The monument consists of the well-preserved remains of a fish weir, dating to the medieval or post-medieval period. A fish weir is usually characterised by a foundation of stone topped with a fence or row of stakes, often with nets attached forming an enclosure within a river or harbour and used for catching, or holding, fish. Llanddona fish weir is crescent-shaped and comprises two slightly curving arms defined by spread banks of stone. The inner arm is some 120m in length and runs at 135 degrees from the shore; the outer extends to a length of 225m and runs in the reverse direction across the bay. The weir's simple form may indicate an early date within the local sequence. It is first recorded in Baron Hill Estate papers of the 17th century and is also marked on a chart of 1748.

It is of national importance for its potential to enhance our knowledge of medieval or post-medieval maritime agricultural practices. The monument is the better preserved of only two surviving weirs of this type in Gwynedd and it retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The structure itself may be expected to contain archaeological information concerning chronology and building techniques.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw

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