American lobster Homarus americanus responses to construction and operation of an offshore wind farm in southern New England

Abstract

Construction and operation of the Block Island Wind Farm (BIWF) has occurred against a background of declining American lobster Homarus americanus abundance and harvests in southern New England (SNE), USA. Potential effects of BIWF on a portion of the SNE stock were assessed with a ventless trap survey conducted at 2 blocks near BIWF and 2 blocks at a reference location located 22 km northeast from May through October, 2013-2019. Collaboration with the fishing industry to select sampling locations yielded a reference location on favored fishing grounds to document potential effects on the fishery. Results of the before-after-control-impact (BACI) design revealed American lobster catches decreased between the baseline and operation time periods at the wind farm (-30%) and reference (-18%) locations, and this decrease was greater as a proportion of the overall catch near the wind farm (BACI interaction [α = 0.10]), but similar in absolute numbers (-0.8 vs. -0.9 lobsters trap-1). Catch rates of females carrying late-stage eggs were relatively high in the reference location where bottom water temperatures were lowest. An adverse impact of turbine installation activities on lobster catches was not apparent. Temporal variation in lobster catch rates was similar to that observed in other regional ventless trap surveys. The design decision to document lobster metrics on the deeper fishing grounds satisfied fishing industry concerns. However, potential BIWF effects cannot be separated from regional shifts in lobster distributions to deeper, colder habitat, which reflects one limitation of using a BACI design when effects, if present, likely follow a spatial gradient.