Quantifying the fine-scale behaviour of spawning run river lamprey (Lampetra fluviatilis) approaching a low-head weir retrofitted with studded tiles

Fish passes (or fishways) designed to mitigate for the impeded movement of migratory fish at anthropogenic structures (such as dams and weirs) often function poorly. This is particularly the case for anguilliform species such as lamprey (Petromyzon spp. and Lampetra spp.). Poor swimming capability (in comparison to e.g. salmonids) and a lack of understanding of behaviour in response to hydrodynamic cues are considered key reasons limiting the performance of mitigation measures. A field study employing Passive Integrated Transponder (PIT) and fine-scale (sub-metre) acoustic telemetry was conducted on the River Derwent (Yorkshire, UK) in Winter (November – December) 2017. The aim of the study was to assess river lamprey behaviour and passage at a low-head weir retrofitted with studded tiles designed to aid upstream movement. In this talk, the acoustic telemetry data will be presented, outlining fine-scale behaviour and weir approach routes of lamprey in relation to hydrodynamics that were measured using a remotely operated Acoustic Doppler Current Profiler. How this data can be quantified into “behavioural rules” to parameterise Agent Based Models will be discussed and examples provided. Such models will enable better predictions of fish movements to be made as they encounter anthropogenic structures and guide the design of more effective mitigation measures, such as fish passage and screening systems