Abstract
The University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) and Massachusetts Lobstermen’s Association (MLA), conducted a standardized ventless lobster trap survey and tagging study in Vineyard Wind’s Lease Area OCS-A 0501, on the Outer Continental Shelf (OCS). In northern portion of the Lease Area, termed the 501 North (501N) Study Area, populations of adult lobster, larval lobster, and black sea bass were sampled and compared to those in the easterly adjacent Control Area (see Figure 1).
The primary goal of this project was to identify baseline conditions in the 501N Study Area and adjacent Control Area, to then compare potential impacts on several marine species of proposed wind development activities in the 501N Study Area to the Control Area. To establish a first-year baseline, a Before-After-Control-Impact (BACI) design was employed to detect eventual patterns of sustained difference. Our primary objectives for this project were to:
- Estimate the size and distribution of lobster and black sea bass populations in the 501N Study Area and adjacent Control Area;
- Classify population dynamics of these two species such as length, sex, reproductivity success, age, diet, and disease;
- 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 501N Study Area and adjacent Control Area) were identified and divided into smaller sub-areas called aliquots. An aliquot (within each lease block) was randomly selected and served as a sampling location that held constant throughout the survey. There were 15 sampling sites selected in the 501N Study Area and 15 in the Control Area, for a total of 30 stations. Each location was sampled two times per month from July to October 2019 using a string of traps. Ventless traps were alternated with standard vented traps to compare differences in catch rates and size selectivity of both trap types. A single, unbaited sea bass pot was also attached to one end of a string. Surface plankton tows were conducted twice per month from June to August, then once per month in September and October due to equipment issues and weather restrictions.
A total of 351 lobsters were sampled between both study areas and trap types: 214 in the 501N Study Area, with an average size of 90.75 ± 2.2 millimeter (mm), and 137 in the Control Area, with an average size of 91.25 ± 2.4 mm. The 501N Study Area yielded an overall male: female ratio of 1.6:1, and the Control Area ratio was 2.4:1. A total of 264 black sea bass were sampled from commercial sized sea bass pots at each location; 99 in the 501N Study Area and 165 in the Control Area. Larval lobster samples were collected at each location with a neuston net; for the season we collected 23 total lobster larvae ranging from stages two to four. The average larval lobster density was 0.07 larvae / 1000m3 in the development area and 0.04 larvae / 1000m3 in the Control area.
Jonah crab were reported independently of other bycatch due their existence as commercially important target species. Overall catch during the survey was 1,918 crabs, with 1,160 sampled in the 501N Study Area and 758 in the Control Area. Jonah crab data are presented in Appendix 1, while counts of additional bycaught species are presented in Appendix II.
The substrate and habitat classification were determined from data collected by a separate SMAST Drop Camera Survey of Benthic Communities and Substrate in Vineyard Wind Lease Area OCS-A 0501 and Control Area. Dominant substrate in these areas were shown to be sand with a few areas of gravel in both the 501N Study Area and Control Areas (Appendix III, Figure 1)