Risks to different populations and age classes of gannets from impacts of offshore wind farms in the southern North Sea

Christopher J Pollock,Jude V Lane,Lila Buckingham,Stefan Garthe,Ruth Jeavons,Robert W Furness,Keith C Hamer

doi:10.1016/j.marenvres.2021.105457

Christopher J Pollock, Jude V Lane + Show 5 more

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https://doi.org/10.1016/j.marenvres.2021.105457

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Abstract

The southern North Sea holds the world's highest concentration of offshore wind farms (OWFs). Northern gannets (Morus bassanus), a species considered at high risk from OWF impacts, show a strong seasonal peak there in November, but it is unclear which populations and age classes are most at risk of collision with wind turbines. We tagged adult and juvenile gannets at the world's largest colony (Bass Rock) and reviewed two sources of survey data for different age classes to study their movements through southern North Sea waters. Tracked birds showed peak numbers in the southern North Sea in mid-October, with much smaller numbers there during November. Adults were distributed throughout the area, including waters close to OWFs, whereas juveniles were confined to the coast. Survey data indicated high proportions of immature gannets in southern North Sea waters, suggesting higher collision risk than for adults. Gannets present in November may be predominantly from colonies further north than Bass Rock.

Highlights

Development of renewable energy resources is increasing apace in an attempt to reduce reliance on fossil fuels
A total of 3901 gannets were detected during digital aerial surveys of prospective Offshore wind farms (OWFs) sites in the southern North Sea of which 91% were identified as adults (n = 3542), 5.1% as immatures (n = 198) and 1.3% as juveniles (n = 46)
Adults from Bass Rock were apparently more likely than juveniles to travel on paths that intersected current or planned OWFs, placing them at greater po tential collision risk, during their autumn migration

Summary

Introduction

Development of renewable energy resources is increasing apace in an attempt to reduce reliance on fossil fuels. The UK is currently the largest offshore wind market, with 36% of global installed capacity (deCastro et al, 2019), calling particular attention to impacts of OWFs on marine life in UK waters. Potential adverse effects of OWFs on seabirds include risks of collision with turbine blades, barrier effects when energy is expended to avoid turbines, and displacement through exclusion from feeding grounds (Furness et al, 2013). The extent of these different effects depends upon birds’ behaviour (e.g. home range size, flight height and speed) and varies seasonally (Lane et al, 2020)

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