Passive acoustic recordings collected during summer 2015 at an artificial reef (sunken barge) south of Long Island, New York revealed regular visitation by groups of delphinid odontocetes. Detected signals included social (whistles) and foraging (short-interval echolocation) signals of odontocetes, as well as signals specific to bottlenose dolphins (Tursiops truncatus) and two known prey species. Visual observations, high broadband noise levels, and presence of acoustic signatures specific to boats indicated heavy use of this site by recreational fishers. Boat detections were significantly more frequent on weekends and between sunrise and sunset. Dolphin detections did not vary diurnally and were significantly lower on weekends, possibly due to avoidance of persistent noise disturbance. Bottlenose dolphins produce low-frequency, narrow-band signals that are highly susceptible to masking by boat noise. However, no significant difference was observed in the duration, average peak frequency, or frequency range of these signals when boat noise was present or absent. Our findings demonstrate the benefits of passive acoustic techniques in monitoring soniforous users (including humans) of artificial reef habitats in these waters. Attraction of both human fishers and odontocetes to artificial reefs may increase direct human-predator interactions as well as indirect ecological competition.