Abstract
The University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) and Massachusetts Lobstermen’s Association conducted a standardized ventless lobster trap survey and tagging study in Vineyard Wind 1 LLC’s (Vineyard Wind’s) Lease Area OCS-A 0501 (termed the “VW1 Study Area”) and an adjacent Control Area. Populations of adult and larval American lobster (Homarus americanus), and black sea bass (Centropristis striata) were sampled and compared between the VW1 Study Area and the adjacent Control Area (Figure 1).
This project aimed to identify baseline conditions in the VW1 Study Area and adjacent Control Area to later compare potential impacts on several marine species of proposed offshore wind development and construction activities in the VW1 Study Area and the Control Area between years. The baseline data will contribute to an eventual Before-After-Control-Impact (BACI) design to detect patterns of difference. Our primary objectives for this project were to:
- Estimate the size and distribution of lobster and black sea bass populations in the VW1 Study Area and adjacent Control Area;
- Quantify aspects of the life history of these two species such as length, sex, reproductivity success, age, diet, and disease prevalence;
- Estimate the relative abundance and distribution of planktonic species, such as larval lobster, in the neustonic layer of each area, using a towed ichthyoplankton net at each survey location; and
- Obtain movement patterns of adult lobsters through a tagging study.
For the lobster, black sea bass, and planktonic sampling locations, we employed a random sampling design by stratifying the area of interest using existing lease blocks. Lease blocks within the two study areas, the VW1 Study Area and adjacent Control Area, were divided into smaller sub-areas called aliquots. Within each lease block, an aliquot was randomly selected to serve as a sampling site throughout the survey season. Fifteen sampling sites were selected in each of the VW1 Study Area and Control Area, for a total of 30 stations. Each sampling site was sampled two times per month from May to October 2023 using a string of seven traps. On each string, six ventless traps were alternated with standard vented traps to compare differences in catch rates and size selectivity between trap types. A single, unbaited sea bass pot was also attached to one end of each string. Surface plankton tows were conducted twice per month from May to October.
A total of 431 lobsters were sampled between study areas and trap types: 248 in the VW1 Study Area, with an average size of 93.3 ± 1.2 millimeters (mm), and 183 in the Control Area, with an average size of 89.8 ± 1.4 mm. The male-to-female ratio was 1.4:1 in the VW1 Study Area and 1.6:1 in the Control Area. A total of 523 black sea bass were sampled between study areas from commercial-sized sea bass pots at each location: 118 in the VW1 Study Area and 405 in the Control Area. The average length of black sea bass was 28.51 ± 0.96 centimeters (cm) in the VW1 Study Area and 29.78 ± 0.53 cm in the Control Area. Larval lobster samples were collected at each location with a neuston net; throughout the season, a total of 44 lobster larvae were collected ranging from stages one to four. Of these, 32 were collected in the VW1 Study Area and 12 were collected in the Control Area. The average larval lobster density was 0.10 ± 0.05 larvae per 1,000 cubic meters (m3) in the VW1 Study Area and 0.04 ± 0.03 larvae/1,000 m3 in the Control Area.
Jonah crab was reported independently of other bycatch given their status as a commercially important species. A total of 4,847 Jonah crabs were caught: 3,266 caught in the VW1 Study Area and 1,581 in the Control Area. Jonah crab data are presented in Appendix I. Counts of other bycatch species are presented in Appendix II.
Substrate and habitat classifications were determined from data collected by a separate SMAST drop camera survey of benthic communities and substrates in the VW1 Study Area and Control Area. The dominant substrate in both the VW1 Study Area and Control Area was sand (Appendix III).