Ecological indicators to monitor offshore wind interactions with fisheries resources

Offshore wind development (OWD) will generate much needed renewable energy, but it will also introduce several stressors to the marine ecosystem. Therefore, there is a need to develop information-rich monitoring programs to assess ecological impacts and inform solutions to mitigate adverse effects. This paper evaluates potential indicators of OWD impacts on fisheries resources that could be considered for monitoring programs, including indices of aggregate biomass, sensitive species, fish size, and trophic dynamics. Short-term (year-to-year) variability and the direction and strength of long-term trends were explored at both the scale of the US Southern New England wind energy area (WEA) and at the scale of the Southern New England region. The majority of candidate OWD indicators exhibited substantial temporal variability at either the WEA scale, the region scale, or both, highlighting the importance of addressing temporal variability in the design and duration of monitoring programs. Recommendations are provided to advance informative monitoring approaches both in the USA and elsewhere where such approaches are urgently needed. Among these is a recommendation for a minimum of 3–5 years of baseline data collection and continued monitoring for the lifetime of the wind project. This will enable an understanding of the temporal structure inherent to the time series of ecological indicators measured so that OWD impacts can be disentangled from those caused by other ecosystem pressures.