Offshore wind farm effects on flounder and gadid dietary habits and condition on the northeastern US coast

Dh Wilber,Gr Decelles,M Griffin,L Brown,Da Carey

doi:10.3354/meps13957

Dh Wilber, Gr Decelles + Show 3 more

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https://doi.org/10.3354/meps13957

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Abstract

The first offshore wind farm in North America, Block Island Wind Farm (BIWF), was built on a pilot scale (five 6 MW turbines) approximately 5 km southeast of Block Island, Rhode Island. Potential effects of the BIWF on dietary habits were examined for fish collected in a trawl survey conducted monthly over 7 years (October 2012 to September 2019). Stomach content analysis was conducted on 3457 flounder, gadids, and black sea bass collected near BIWF and in 2 reference areas during baseline, construction, and operation time periods. Other trophic metrics such as fish condition, stomach fullness, and % empty stomachs were examined for an effect of wind farm operation. Temporal variation in trophic metrics was more common than spatial differences, with no consistent indication of an effect of wind farm operation across metrics or species. Prey accumulation curves indicated that diets were adequately characterized with sample sizes of approximately 40 stomachs for most time period by area combinations. Diet composition of hakes and flounder in all areas included a greater proportion of mysids and amphipods during the wind farm operation time period. Summer flounder and winter flounder condition was lower during the operation time period in all areas. Inclusion of mussels and associated epifauna (mysids) in fish diets following turbine installation indicate fish forage on the colonized turbines. Although substantial changes to fish diets were not evident at BIWF, cumulative trophic effects of larger wind farms should be examined as the offshore wind industry expands on the northeastern US coastline.

Highlights

Offshore wind development on the northeastern US coast has been accelerating since the first North American offshore wind farm (OSW), Block Island Wind Farm (BIWF), went into operation in October 2016
The stomachs of 3457 fish were analyzed to determine the diets of Atlantic cod (n = 98), black sea bass (n = 110), red hake (n = 168), silver hake (n = 624), spotted hake (n = 392), summer flounder (n = 435), and winter flounder (n = 1630)
A complete list of strong seasonal differences in prey composition at stomach contents identified to lowest practical identification level (LPIL) and the fre- the aggregate taxon level for any species examined quency of occurrence by year of each prey item for

Summary

Introduction

Offshore wind development on the northeastern US coast has been accelerating since the first North American offshore wind farm (OSW), Block Island Wind Farm (BIWF), went into operation in October 2016. The Bureau of Ocean Energy Management (BOEM) projects 2000 turbines will be constructed in 15 active lease areas along the eastern US coast by 2030 (BOEM 2020). Given this rapid expansion of OSWs, it is important to understand how the introduction of turbines, sometimes with scour protection around foundations and cables, affects fish abundance and distribution, and their trophic interactions. The installation of the turbine foundations, initiated the transition of benthic habitat from a sandy substrate dominated by polychaetes to organically enriched sediments with mussels and associated macrofauna, such as crabs, mysids, hydroids, anemones, and sea stars (HDR 2020)

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