Abstract
Vineyard Wind 1 LLC (Vineyard Wind), in collaboration with the University of Massachusetts Dartmouth’s School for Marine Science and Technology (SMAST), has developed a monitoring plan to assess the potential environmental impact of the proposed offshore renewable energy development on marine fish and invertebrate communities in Lease Area OCS-A 0501 (the “VW1 Study Area"). One component of the monitoring plan is a demersal trawl survey modeled after the Northeast Area Monitoring and Assessment Program (NEAMAP), a regional survey used to evaluate nearshore fish communities. The data collected from this survey aims to provide information on species abundance, distribution, population structure, and community composition for future impact analysis. Pre-construction monitoring took place between 2019 and 2022. The data presented in this report are meant to evaluate the impact of construction activities in 2023 and 2024 on local fish communities.
Four seasonal trawl surveys were conducted using a commercial fishing vessel in the spring, summer, and fall of 2023 and in the winter of 2024. Construction activities in the VW1 Study Area included the installation of scour protection, wind turbine foundations, inter-array cables, and an electrical service platform (ESP). These activities varied seasonally based on the project's progression. Twenty tows were conducted each season in the VW1 Study Area, with an additional 20 tows performed in a neighboring region serving as a control (the “Control Area”). Tow locations were randomly selected using a spatially balanced sampling design. A standardized bottom trawl with a 1-inch knotless liner was towed behind the vessel for 20 minutes at a speed of 3 knots. Acoustic sensors were utilized to monitor the net’s performance and ensure accurate trawl geometry. The catch was sorted by species, and both aggregated weights and individual fish lengths and weights were recorded.
A total of 160 tows were completed during the 2023/2024 survey year, divided equally between the VW1 Study Area and the Control Area, and across the four seasons. A total of 47 species were observed throughout the survey year, with the majority of the catch consisting of a small number of dominant species. Butterfish, scup, silver hake, little skate, and Atlantic longfin squid were the five most abundant species in both the VW1 Study Area and Control Area, accounting for 86.6% and 84.8% of the total catch weight, respectively. Seasonal and annual variations in fish communities were noted during the survey year, similar to what was found in pre-construction baseline surveys. Various construction activities, along with temporal changes in fish communities, created a complex environment for assessing the potential impacts of the associated activities. Despite these varying conditions, the surveys were able to provide a general assessment of the local fish communities.
Throughout the study period, significant variations in species abundance were observed; however, most of these changes occurred either in both study areas (i.e., a project phase effect) or were consistent with pre-construction differences between the two areas (i.e., an area effect). Data from the spring survey did not show any consistent, homogeneous patterns of avoidance in the VW1 Study Area, suggesting minimal impacts from the associated construction activities. Disparities in catch rates were noted between the two study areas during the summer survey for Atlantic longfin squid, silver hake, and scup. Reduced catch of these species in the VW1 Study Area may indicate changes in long-term trends or localized avoidance of the area. Further evidence of localized avoidance was apparent during the fall survey when scup, butterfish, and silver hake exhibited low catch rates in the northern half of the VW1 Study Area. Construction activities during this period were concentrated in this location and included wind turbine foundation installation and inter-array cable burial. These data suggest that avoidance is highly localized, as high catch rates were observed in the southern half of the VW1 Study Area. Additionally, high catch rates were recorded in areas where previous wind turbine foundation installation had taken place, suggesting short-term avoidance. Furthermore, avoidance was not consistent across species, as it was not observed in little skate, Atlantic longfin squid, black sea bass, or summer flounder. Finally, no evidence of avoidance or differences in fish communities was noted during the winter survey after the seasonal cessation of underwater construction activities. In summary, the VW1 Study Area is a highly dynamic region with strong seasonal changes in fish communities. Some evidence of short-term, localized avoidance was observed with the ongoing construction activities; however, this was limited and varied between species. Additional monitoring will be required to assess the long-term impact of the Vineyard Wind 1 project on local fish populations.