Abstract
Vineyard Wind LLC, 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 impacts of the proposed offshore renewable energy development on the northern portion of Lease Area OCS-A 0501 (the 501 North Study Area) on marine fish and invertebrate communities. One component of the monitoring plan is a bottom trawl survey. The trawl survey is modeled after the Northeast Area Monitoring and Assessment Program (NEAMAP), a regional survey used to assess near-shore fish communities. The data collected from this survey is intended to provide baseline information on species abundance, population characteristics and community structure to be used in a future impact analysis. Vineyard Wind is also conducting fisheries studies within the southern portion of Lease Area OCS-A 0501 (the “501 South Study Area”) and within Lease Area OCS-A 0522; these studies are reported separately.
Four seasonal trawl surveys were conducted using commercial fishing vessels. Twenty tows were conducted each season in the 501 North 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 random 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 its trawl geometry. The catch was sorted by species. Aggregated weight as well as individual fish lengths and weights were collected.
A total of 160 tows were completed throughout the year split equally between the 501 North Study Area and the Control Area, and among four seasons. The catch data obtained shows a dynamic area with a diversity of marine species. A total of 45 species were collected; however the majority of the catch was comprised of a small subset of the observed species. The four most abundant species (spiny dogfish, little skate, silver hake and red hake) were shared between the two survey areas and accounted for 78% of the total catch weight in the 501 North Study Area and 71% of the total catch weight in the Control Area. The next four most abundant species (winter skate, scup, butterfish and alewife) were similarly shared between regions and added an additional 15% to 20% of the total catch. All species caught displayed seasonal variations in distribution and abundance. The data indicate a unique assemblage of species and abundance in each of four seasons. The spring, summer and fall surveys display significant overlap in species assemblages; however catch rates and the population structure varied. The winter survey appears to be relatively unique in the species assemblage which is primarily dominated by pelagic species. No differences in species assemblages were observed between the two study areas.