Abstract
The rapid expansion of offshore wind development along the east coast of the USA has raised concern over its potential effects on large whales, especially the Critically Endangered North Atlantic right whale. This study examines changes in vessel traffic associated with offshore wind development to assess the potential for increased risk of vessel strikes and corresponding noise exposure. Monthly Automatic Identification System (AIS) vessel data were obtained from before, during, and after the construction of 3 wind energy projects: the Block Island Wind Farm, Coastal Virginia Offshore Wind Pilot Project, and Vineyard Wind I. We then conducted a spatiotemporal analysis of vessel density on monthly rasters of vessel occupancy time. Vessel density increased in very localized regions surrounding wind turbine generator (WTG) sites (i.e. within 2 km) during the active construction period by up to 36.41 additional monthly (h km-2) on average, although notable increases in vessel density only occurred during a subset of months within the broader construction window. Increases in post-construction vessel traffic at WTG sites were minimal (up to 4.98 monthly h km-2 on average compared to pre-construction vessel traffic) and on par with the general increase in vessel traffic that has occurred along the eastern seaboard in the past decade. Our results indicate that the threat of increased vessel traffic associated with offshore wind development is temporally limited to the construction period and spatially limited to the areas directly adjacent to the WTGs. This constrained risk can be mitigated by employing restrictions on vessel speed and by restricting active construction to seasons when North Atlantic right whales are not present.