First record of the Indo-Pacific humpback dolphins (Sousa chinensis) southwest of Hainan Island, China

Abstract

Background: Populations of Indo-Pacific humpback dolphins (Sousa chinensis) in China were known to be distributed from the Beibu Gulf near the border with Vietnam to the mouth of the Yangtze River. According to existing studies, the waters around Hainan Island, China, were not considered to be part of the humpback dolphins' distribution. Results: In 2014, for the first time, we recorded humpback dolphins in waters southwest of Hainan Island.

Habitat configuration for an obligate shallow‐water delphinid: The Indo‐Pacific humpback dolphin, Sousa chinensis, in the Beibu Gulf (Gulf of Tonkin)

“…In these three major habitats, systematic surveys are regularly conducted in the Dafengjiang River estuary and Hepu Dugon Reserve, as well as their adjacent waters (Chen et al, ; Wu, Jefferson, et al, ). In habitats other than at these two sites, empirical baselines of humpback dolphin distribution and habitat use are still not available, even though systematic surveys have been recently conducted in the south‐western Hainan habitat (Li et al, ). These information gaps require immediate survey efforts to fill and concurrently verify model predictions.…”

“…Distribution of the Indo‐Pacific humpback dolphin has been reported in the Red River estuary (RRE) in Vietnam and Dafenjiang River estuary (DRE), Hepu Dugong Reserve (HDR) and southern‐west of Hainan in China. Black crosses indicate humpback dolphin sightings from opportunistic surveys in Hainan (a) and Vietnam (b) (Li et al, ; Smith et al, ) that were not used in the Maxent modelling…”

“…In Chinese waters, occurrence of Indo‐Pacific humpback dolphins is reported from several ‘discontinuous’ habitats (Chen et al, ; Chen, Hung, Qiu, Jia, & Jefferson, ; Jefferson, ; Li et al, ; Wang, Yang, Hung, & Jefferson, ; Wu, Jefferson, et al, ; Wu, Xu, et al, ; Xu et al, ). This ‘discontinuity’, however, sometimes comes from the lack of systematic surveys rather than true habitat configuration, and thus should not be regarded as habitat configuration baselines (Jefferson & Hung, ; Jefferson & Smith, ; Wu, Xu, et al, ).…”

“…In the Beibu Gulf (as it is called in China), or Gulf of Tonkin (as it is referred to in Vietnam), occurrence of Indo‐Pacific humpback dolphins is systematically surveyed at Hepu Dugon Reserves (Chen et al, ) and the Dafengjiang River estuary and its adjacent waters (Chen et al, ; Wu, Jefferson, et al, ; Wu, Xu, et al, ). Besides these two sites, sporadic reports of humpback dolphin occurrence include the Red River estuary in Vietnam (Smith et al, ) and south‐western Hainan Island in China (Li et al, ). Information gaps in humpback dolphin habitat configuration are evident and need to be filled.…”

Indo‐Pacific humpback dolphins (Sousa chinensis) in the Moyang River Estuary: The western part of the world's largest population of humpback dolphins

“…One humpback dolphin species occurring in the coastal waters of eastern India throughout South‐east Asia to central China (Jefferson & Smith, ) is the Indo‐Pacific humpback dolphin ( Sousa chinensis ). Previous studies on population assessment have only been conducted in a few regions of this species' range, including those in coastal waters of China (B. Chen et al, ; T. Chen, Hung, Qiu, Jia, & Jefferson, ; Jefferson & Hung, ; Li et al, ; J. Wang et al, ; J.Y. Wang et al, ; X. Wang, Wu, Turvey, Rosso, & Zhu, ; Xu et al, ), Malaysia (Minton, Poh, Peter, Porter, & Kreb, ) and Thailand (Jutapruet et al, ).…”