Effects of offshore wind farm (OSW) development in the US on fishery resources have been predicted based on European experience. A seven-year study of the first US OSW documented the response of demersal fish and invertebrates to construction and operation. Local fishermen and scientists designed a monthly demersal trawl survey using a Before-After-Control-Impact (BACI) design to assess potential effects of Block Island Wind Farm (BIWF), a pilot scale 30 MW project completed in 2016. Common species did not exhibit statistically significant (α = 0.10) BACI interactions in catch per unit effort (CPUE) due to BIWF operation. CPUE of structure-oriented species, such as black sea bass (Centropristis striata) and Atlantic cod (Gadus morhua), increased at BIWF following turbine installation. Fall and spring biomass varied synchronously between BIWF and a regional survey for several species including longfin squid (Loligo pealeii) and winter flounder (Pseudopleuronectes americanus). Spatial-temporal interaction between reference areas provided an estimate of the minimum effect sizes (approximately 40% to 63% among the fish evaluated) that may be considered ecologically significant when assessing potential OSW impacts. Results from this first North American OSW fisheries monitoring study provide valuable information for future OSW development on the northeastern US coastline.