Brendan

River Lampreys (Lampetra fluviatilis) at Annacotty Weir on the River Mulkear, Co. Limerick. They are attracted to the old sluice gate at the weir and attempt to enter crevices where water flows through cracks in the stonework. This behaviour could help inform the design of a novel lamprey pass for this and other similar sites. It is possible that some lampreys already get past the weir in this way. However, many are likely to become trapped. In the video, lampreys emerging from the stonework at higher levels are clearly visible. These are individuals that entered the structure and are being washed out again. They climbed to this level via leaks and cracks within the stonework. Others emerge from leaks on the opposite side of the sluice gate and are washed into the tailrace. The stonework at Annacotty Weir originates from an older mill weir that once existed at this site. The main part of the current weir, constructed from concrete, was built in the 1990s to replace the earlier stone structure. Most lampreys are drawn to the older section of the weir and the sluice gate. Lampreys attempt to pass this weir repeatedly on suitable nights over several months. They suffer heavy losses as a result of predation and poaching for angling bait. Those that survive spawn below the weir in spring. Annacotty Weir blocks access to over 98% of the River Mulkear catchment for migratory lampreys. It is an ornamental structure and serves no functional purpose. The River Mulkear forms part of the Lower River Shannon Special Area of Conservation (SAC), and River Lamprey is a Qualifying Interest of this Natura 2000 site. It is worth noting that Annacotty Weir is not unique in its impacts on lampreys. There are weirs and other barriers on the lower reaches of almost every river in Ireland.