But stakes like these are the surviving bones of fish weirs, one of the oldest methods of catching fish known in Ireland, and the eastern shore of Canon Island holds at least two distinct clusters of them.

A fish weir typically works by using a barrier, often a fence of woven rods or nets fixed to upright stakes, to trap fish as the tide retreats. The technique is ancient and was widely used along Irish estuaries and coastlines from prehistory well into the early modern period. On Canon Island, which sits in the Fergus Estuary in County Clare, two particularly substantial stakes were recorded approximately 35 metres north of a separate group of stakes at the same site. Researchers noted that these two uprights are noticeably more robust than those of the neighbouring cluster, suggesting either a different phase of construction or a structural role that required heavier timber. The estuary setting would have made Canon Island well suited to this kind of fishing; the tidal rhythms of a sheltered inlet are ideal for the slow, patient logic of a fixed weir.