They are the remains of an ebb-weir, a structure designed to trap salmon as the tide retreated, funnelling fish into a net or enclosure left exposed by the falling water. The technique is ancient and, in its quiet way, surprisingly durable. These particular posts have outlasted the industry they served by well over a century.

The weir here has a long paper trail. Salmon weirs in this part of Wexford are mentioned in the foundation charter of Dunbrody Abbey, the Cistercian house established nearby in the twelfth century, which suggests the fishery was already an organised concern when the monks arrived. By 1541 the weir known as Scarre was being operated by a man named Nicholas Key. Four years later, in 1545, it passed by grant to Sir Osborn Itchingham, and the Itchingham family held onto it for the better part of a century, with the weir still recorded in their possession in 1619 and again in 1635. In 1865 a Fishery Commission inquiry formally identified the weir at Buttermilk Castle as the same historical Scarre weir, and it was permitted to keep fishing. It finally ceased operation in 1902, though there are suggestions it may have seen some use again after that.

The posts are visible only at low tide, so timing matters if you want to see what remains. Buttermilk Castle, the structure with which the weir is associated, provides a locating landmark along the shoreline near Nook in south County Wexford.