Abstract
Vineyard Wind 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 the northern portion of Lease Area OCS-A 0501 (the “501N Study Area). One component of the monitoring plan is a demersal trawl survey. The trawl survey is modeled after the Northeast Area Monitoring and Assessment Program (NEAMAP), a regional survey used to assess nearshore fish communities. The data collected from this survey is intended to provide baseline information on species abundance, distribution, population structure, and community composition to be used in a future impact analysis. Pre-construction monitoring started in 2019. Data provided in this report is the second year of pre-construction monitoring, including four seasonal surveys. Vineyard Wind is also conducting fisheries studies within the southern portion of Lease Area OCS-A 0501 (the “501S Study Area”) and within Lease Area OCS-A 0522 (the “522 Study Area”); these studies are reported separately.
Four seasonal trawl surveys were conducted using commercial fishing vessels. Twenty tows were conducted each season in the 501N Study Area. An additional 20 tows were collected in a neighboring region, which will serve as a control (Control Area). Tow locations were randomly selected using a systematic unaligned sampling design. A standardized bottom trawl with a 1” knotless liner was towed behind the vessel for 20 minutes at 3 knots. Acoustic sensors were used to ensure the net’s performance by monitoring the trawl geometry. The catch was sorted by species. Aggregated weights, as well as individual fish lengths and weights, were collected.
A total of 160 tows were completed throughout the year split equally between the 501N Study Area and the Control Area, and among the four seasons. In general, the data were similar to that observed during the 2019/2020 survey year. The catch data obtained shows a dynamic area with a diversity of marine species. A total of 42 species were collected; however, the majority of the catch was comprised of a small subset of the observed species. The five most abundant species (little skate, scup, spiny dogfish, winter skate, and silver hake) accounted for 77% in the Control Area and 78% in the 501N Study Area, respectively. Interannual changes in abundance varied amongst species. All species caught displayed seasonal variations in distribution and abundance. The data indicated a unique assemblage of species and abundance in each of the four seasons. The winter and fall surveys exhibited strong similarity to those in 2019/2020. The spring and summer surveys displayed significant differences from the previous year. In general, catch rates were lower in 2020/2021, compared to 2019/2020, presumably due to differences in survey timing (2019: mid- to late June; 2021: early May) and the resulting cooler bottom water temperatures (~3oC cooler in 2021). Conversely, bottom water temperatures were ~5oC warmer during the 2020 summer survey compared to the 2019 summer survey. As a result, the catch was dominated by heat-tolerant species such as scup, butterfish, and summer flounder. No differences in species assemblages were observed between the 501N Study Area and Control Area.