The effect of offshore windfarms on the distribution, behaviour, and abundance of fish

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Uncertainty around impacts on seabird populations remains a key consenting issue for offshore wind development in the UK, affecting progress towards the increase in deployment of offshore windfarms needed to meet the targets of the British Energy Security Strategy. Seabirds are impacted through collisions, displacement from feeding grounds, and barrier effects on migratory routes or regular flight paths. The cumulative effects of these impacts, the underlying causal relationships behind them, and the extent of habituation over time, are currently not well understood. These effects are being investigated by a new project, funded by the UK Natural Environment Research Council and The Crown Estate's Offshore Wind Evidence and Change Programme, called Ecowings. The project aims to transform the existing evidence base on the cumulative effects of offshore wind on key seabird species, focussing on a region of the UK North Sea, with key species including black-legged kittiwake, common guillemot, razorbill, and Atlantic puffin. This PhD will contribute to that project by studying the fish prey of these animals. OW farms (OWF), in common with other man-made marine structures (MMS), are known to provide three-dimensional habitat, which at the very least aggregates fish and other marine life, and in some MMS, has been shown to enhance production. As is the case with most MMS, we know little about the extent to which fish distribute themselves at distance from the structure, and less about how MMS networks, typified by OWF, can influence behaviour, and abundance in and outside the network. This project aims to examine the distributions of fish in and around OWF, making unique measurements with novel platforms such as Uncrewed Surface Vehicles (USVs) and Autonomous Underwater Vehicles (AUVs). These measurements will be taken concurrently with seabird surveys from aerial surveys. The ECOWINGS datasets will be made available and, to distinguish the studentship from the project, the student will focus on deriving metrics of fish school echotrace descriptors to understand potential impacts on seabird distributions. These metrics are classed as positional (school depth, latitude, longitude, date, and time), morphometric (school height, width, area, perimeter, roughness), energetic (acoustic intensity, which is proportional to density, its variability, centre of mass), and school environment (minimum and maximum depth under the school, school cluster patch size). These have been used to distinguish fish schools, but here will be used to examine how the characteristics of schools of the same species are affected by predator encounters. The datasets derived from the AUV of undisturbed fish schools at the surface will be particularly pertinent for studies of [seabird] predator [fish] prey interactions, particularly for surface-feeding seabirds such as black-legged kittiwakes.