ABSTRACT Although whistles and high‐frequency clicks of Indo‐Pacific humpback dolphins ( Sousa chinensis ) had been documented in many wild populations, the small population inhabiting Xiamen Bay has received limited attention. Monthly surveys from 2021 to 2024 recorded a total of 107 whistles and 33,038 high‐quality clicks. Whistles exhibited mean minimum and maximum frequencies of 5.2 ± 2.2 kHz and 7.5 ± 2.7 kHz, respectively, with a mean duration of 247.6 ± 174.2 ms. Clicks had a peak frequency of 86.4 ± 19.5 kHz, a −3 dB bandwidth of 53.3 ± 14.6 kHz, and a duration of 22.3 ± 6.4 μs. Statistically, clicks from dolphins in the West sub‐region had a higher mean peak frequency, broader −3 dB bandwidth, and shorter duration than those from the East sub‐region, suggesting adaptations to local environmental conditions and vessel noise. No significant difference was observed in whistles between the two communities. These findings indicated a potential risk of population subdivision for the Xiamen Bay population, underscoring the urgency of protective measures that sustain connectivity and reduce anthropogenic pressures.
Peng et al. (Sun,) studied this question.