A preliminary description of Atlantic white‐sided dolphin (Lagenorhynchus acutus) vocalizations

Royal Society of EdinburghAtlantic white-sided dolphins (Lagenorhynchus acutus) are endemic to the North Atlantic Ocean, predominantly inhabiting the cold-temperate and subpolar waters around the continental shelf and slope.Their geographic range extends from the western North Atlantic across to the eastern North Atlantic, and includes the Norwegian and North Seas, but their distribution patterns are not well-understood (Cipriano, 2018;Vollmer et al., 2019).There is a relatively high occurrence of mass strandings by this species, and it is also impacted by anthropogenic threats such as bycatch in a variety of gear types, including trawls and gill nets (Addink et al., 1997;Bogomolni et al., 2010;Couperus, 1997;Kinze et al., 1997;Palka et al., 1997).Additionally, Atlantic white-sided dolphins are hunted, primarily in the Faroe Islands, where, for example, 1,428 individuals were killed in a single drive hunt in 2021 (https:// nammco.no/topics/atlantic-white-sided-dolphin/;Calderan, 2021; Fielding, 2021).They are thus one of the most heavily exploited cetacean species in the North Atlantic, yet also one of the most poorly-understood.Passive acoustic monitoring (PAM) has the potential to contribute to knowledge on their occurrence, but there is only limited information on white-sided dolphin vocalizations (Cones et al., 2023;Hamran, 2014).It is therefore not currently possible to analyze the many data sets collected from acoustic moorings and towed array surveys to improve knowledge of the species' temporal and spatial distribution.Most dolphin species produce tonal and pulsed vocalizations, including whistles, echolocation clicks, and burst pulses.Echolocation clicks are typically associated with foraging and navigation, and whistles and burst pulses with social communication (Au, 1993;Herzing, 1996).Whistles are frequency-modulated tonal sounds (Herman & Tavolga, 1980).Echolocation clicks are short-duration, directional clicks (Au, 1993); burst pulses also comprise clicks, where broadband pulsed signals with significant ultrasonic frequency components are produced with a very high