Sperm whale and dolphin presence in the offshore Gulf of Maine

Offshore wind energy development is planned for the Outer Continental Shelf (OCS) in the U.S. Gulf of Maine (GOM). The GOM is an important habitat for many marine animals including sperm whales and dolphins. In 2019 the Northeast Fisheries Science Center started deploying bottom-mounted passive acoustic recorders in the GOM. Here, the data collected between 2022 and 2023 from one site located in Georges Basin, west of the Northeast Channel, were analyzed for the hourly presence of sperm whales and dolphins using PAMGuard and SoundScope. Sperm whales were detected year-round but presence varied by season. From June 2023 to November 2023 sperm whales had a mean percent presence of 87%. In contrast, from December 2022 to May 2023 sperm whales had a mean percent presence of 8.6%. Dolphins were detected consistently year round and at all times of day. These results indicate this area in Georges Basin may be an important habitat for sperm whales and dolphins and provide a baseline that will be used to assess any future changes. This study supports the idea that sperm whales, classified as Endangered in US waters, and dolphins should be considered in mitigation plans and permitting efforts for offshore wind energy.