There was a medieval fishing weir near Rhos point, some remains of which can still be detected at low tide. It is thought that this was built by the monks from the great Cistercian monastery of Aberconwy. This abbey was originally built on the banks of the estuary of the River Conwy, but was compulsorily relocated later by Edward 1 to Maenan when he wanted the site to build his new town of Conwy and its castle. It is thought that the monks had a small outpost at what is now the Rhos Fynach public house, where they could temporarily stay while maintaining the weir and collecting the fish.
The medieval weir in Rhos consisted of a large V-shaped enclosure made out of wicker fencing. At high tide the fish swam into the structure, and were then trapped in a pool as the tide went out . Weirs such as these were so effective that by Victorian times they were a danger to fishing stocks, particularly salmon. Therefore in 1861 Parliament passed a law ordering their destruction. As a result a second, newer weir in Rhos was demolished. However the new law granted an exemtion where the owner could prove his weir had existed before the time of Magna Carta (i.e. 1215 AD). The owner of the Rhos Fynach weir was able to prove its medieval origins to the satisfaction of the Commissioners, and so it escaped destruction. The weir was amazingly effective and enormous numbers of fish could sometimes be caught. For example in 1850 there was a record catch of 35,000 herring in a single night! The weir even trapped an 8 foot shark in 1865, which was put on display in Llandudno market. On another occasion (in 1907) 10 tons of mackerel were caught in a single tide. The last owner of the weir, one John parry Evans, trained terrier dogs to retrieve salmon from the weir. The first dog he trained, Jack, was so admired that he was awarded with a silver collar and became a popular tourist attraction. Unfortunately he died in 1873 after receiving fatal injuries from another shark trapped in the weir! The weir fell into disuse in the First World War, and regrettably its stakes were later removed as a danger to boats.