Delphinids are commonly observed in Mid-Atlantic waters yet knowledge of their ecosystem use remains limited, generating concerns for potential impacts on these species from future coastal development. Passive acoustic monitoring was used to investigate spatial and temporal variations in the presence of delphinids off of the Mid-Atlantic from June 2022 to November 2023. Soundtraps were deployed to record acoustic data (48 kHz sample rate) on the Atlantic Outer Continental Shelf in two linear arrays off of (1) Chesapeake Bay and (2) Delaware Bay. SoundTrap data were analyzed for dolphin whistles on an hourly time scale, using the PAMGuard whistle and moan detector along with custom python-based detection-viewing software, Soundscope, for validation. Dolphins were detected at all recording locations with varying presence based on region and time of year. While present year round, dolphin acoustic presence peaked in early spring off of the Chesapeake Bay and in early summer off Delaware Bay, suggesting a northern shift in presence as waters warm. At one site off of the Chesapeake Bay, dolphin acoustic presence extended into the winter. These results expand on current knowledge of dolphin habitat use and can be used to guide coastal development plans for lowest impact.
Kratman et al. (Wed,) studied this question.