Final report on the assessment of seabird vulnerability to offshore windfarms in Ireland

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Critchley, Emma
Jessopp, Mark J.
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University College Cork
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It is essential that the potential risks to seabird populations from offshore windfarms in Irish windfarms are assessed prior to development in order to avoid and mitigate impacts. Seabird vulnerability indices have been developed as part of the biological component of EirWind Work Package 4 through updating previously published indices in an Irish context, incorporating new data, and accounting for advances in turbine technology. Two Collision Vulnerability Indices were calculated, one accounting for a turbine sweep zone starting at 20 m above sea level, and one accounting for a turbine sweep zone starting at 40 m above sea level. A separate Displacement Vulnerability Index (DVI) was calculated in order to assess the population level vulnerability to displacement from important habitats due to the siting of offshore wind developments. Vulnerability scores were applied to the most recent seabird distribution data to produce seabird vulnerability maps covering the entire Irish Exclusive Economic Zone (EEZ). Seasonal seabird distribution data were sourced from the ObSERVE aerial survey programme (Rogan et al. 2018) and modelled foraging radius distributions (Critchley et al. 2018). Vulnerability maps were produced for summer and winter showing the areas of highest seabird vulnerability to windfarms, whether due to collision or displacement/avoidance of infrastructure in Irish waters on a broad scale. The outputs of this report determine spatial vulnerability at a national scale to help broad-scale siting decisions, and finer-scale vulnerability maps should be generated within smaller areas of interest to help inform siting decisions and additional survey/data needs to mitigate potential impacts. The relative importance of coastal areas in the summer compared to offshore areas, especially on the south west coast, can be seen across indices. This reflects the concentration of birds in waters surrounding colonies during the breeding season, including internationally important populations. Additional seabird surveys at a national level will help to reduce uncertainty in areas with limited data (e.g. the south and west coasts), and at a site level will provide fine-scale information about areas of highest vulnerability. Vulnerability Indices also illustrate how species and risk factors will vary by site and season. Combined use of vulnerability indices and site specific species distribution maps will provide a powerful tool for defining the species and areas most at risk in a planned development site. Appropriate monitoring and mitigation measures can then be put in place prior to development, with the aim of reducing the environmental impacts from offshore windfarm development.
Seabird populations , Offshore windfarms , Irish windfarms
Critchley, E. and Jessopp, M. (2019) Final report on the assessment of seabird vulnerability to offshore windfarms in Ireland, EirWind Project Deliverable D4.14 Report, MaREI Centre, ERI, University College Cork, Ireland. doi: 10.5281/zenodo.3948474
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