Lateralized swim positions are conserved across environments for beluga (Delphinapterus leucas) mother–calf pairs

•Investigated if captive and wild beluga mother-calf pairs display lateralized swim preferences.•Calves spent more time on the mothers’ right side than the left for both populations.•This trend was consistent across most of the first two years of development.•This lateralized behaviour may facilitate processing social information or familiar stimuli. Research with wild belugas has indicated that, during mother–calf swims, calves spend more time on their mothers’ right side, which enables the calves to maintain visual contact with their mothers using their left eye. This bias may facilitate processing of social information by the right hemisphere, much like human and non-human primates and other animals. The current study explored the social laterality of the Cook Inlet, AK beluga population in comparison to a beluga population in managed care. As expected, the results indicated that the calves spent more time on the mothers’ right side than the left for both populations. We also examined the developmental trend for the belugas in managed care and found that the calves generally preferred to swim on their mother's right side across most months, although there was an inversion during the third quarter when a left-side preference appeared. Individual differences were present. The results corroborate previous research conducted with two wild beluga populations from the White Sea and from the Sea of Okhotsk in which a left-eye bias was displayed by calves when swimming with their mothers. In conclusion, a preference for a lateralized swim position appears to be conserved across wild and managed care settings, and this lateralized swim position may facilitate the processing of social information or familiar stimuli for the calves.