Framework for assessing and mitigating the impacts of offshore wind energy development on marine birds

Offshore wind energy development (OWED) is rapidly expanding globally and has the potential to contribute significantly to renewable energy portfolios. However, development of infrastructure in the marine environment presents risks to wildlife. Marine birds in particular have life history traits that amplify population impacts from displacement and collision with offshore wind infrastructure. Here, we present a broadly applicable framework to assess and mitigate the impacts of OWED on marine birds. We outline existing techniques to quantify impact via monitoring and modeling (e.g., collision risk models, population viability analysis), and present a robust mitigation framework to avoid, minimize, or compensate for OWED impacts. Our framework addresses impacts within the context of multiple stressors across multiple wind energy developments. We also present technological and methodological approaches that can improve impact estimation and mitigation. We highlight compensatory mitigation as a tool that can be incorporated into regulatory frameworks to mitigate impacts that cannot be avoided or minimized via siting decisions or alterations to OWED infrastructure or operation. Our framework is intended as a globally-relevant approach for assessing and mitigating OWED impacts on marine birds that may be adapted to existing regulatory frameworks in regions with existing or planned OWED

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<p><b>Species Distribution Model density blue whales (A), humpback whales (B), and fin whales (C).</b> Density predictions derived from Becker et al. 2016. Note that to facilitate comparison across species, the scale breaks are the same with the exception of the top class maximum.</p

Mortality within sovereign waters (3 Nm offshore) for each of the three west coast states, California, Oregon and Washington.

<p>Mortality per 100,000 km² and percent of total study area mortality are also reported for each state.</p

Mortality within National Marine Sanctuaries.

<p>Mortality per 100,000 km² and percent of total study area mortality are also reported for each sanctuary.</p

Mortality on and off the continental shelf (defined by the 200-meter isobath).

<p>Mortality per 100,000 km² and percent of total study area mortality are also reported for each region.</p

Areas classified as above the study area mean (orange) and greater than the study area 90^th percentile (red).

<p>Panels depict whale mortality for blue (A), humpback (B), and fin (C). Dashed lines represent the National Marine Sanctuaries.</p

Total study area mortality estimates (July-December) for each species and three different models incorporating different estimates of collision avoidance.

<p>Potential Biological Removal (PBR) limits (annual) are included for each species for reference. Stranding extrapolations (annual) are based on 5% (best) and 17% (low) carcass recovery rates.</p

Statistics of humpback whale strike mortality within the Biologically Important Areas (BIAs) defined in Calambokidis et al. 2015.

<p>Total mortality, mortality per 100,000 km² and percent of total study area mortality are reported for each BIA.</p

Variables used in the strike risk model and their sources.

<p>We report the expected likelihood of spatial heterogeneity for each variable and whether that variability could be included in the model.</p