The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Marine Protected Areas (MPAs) are effective tools for the conservation and management of marine ecological environments. China is home to the largest population of the Indo-Pacific humpback dolphin (IPHD) in the world, which can be roughly divided into seven geographic populations. Currently, 14 MPAs for the IPHD have been established. However, research assessing the protection level of these MPAs is relatively limited. This study examines six environmental factors closely associated with the IPHD: distance from shore (DS), bathymetry, chlorophyll-a concentration, sea surface temperature (SST), salinity, and velocity. Using the MaxEnt model, we simulated the habitat preference characteristics and suitability of the IPHD in China, comparing the relative levels of protection among different populations. The results indicate that: (1) The response of the IPHD to influencing factors varies at different research scales. At the national scale, the factors are ranked in order of contribution from highest to lowest as follows: velocity (6.0053), chlorophyll-a concentration (0.4898), bathymetry (0.1445), SST (0.1425), salinity (0.0648), and DS (0.01). (2) The areas of superior suitability are the smallest (approximately 7,378 km²), found only in the potential distribution areas of the Pearl River Estuary population (7,114 km²) and the western coast of Taiwan (256 km²). The medium suitability areas cover 41,163 km², while the marginal suitability areas are 46,440 km²; the poor suitability areas are the largest (approximately 62,123 km²). (3) The Pearl River Estuary population has the highest relative protection level (65.49%), followed by the western coast of Taiwan population (56.03%), and the Shantou population in Guangdong has the lowest relative protection level (15.04%). Various patterns of relative protection levels were observed: areas with well-considered site selection and larger designated ranges have higher relative protection levels (Pearl River Estuary population); areas with insufficient site consideration but larger designated ranges have relatively high protection levels (western coast of Taiwan population); well-considered sites but insufficient designated ranges require enhanced protection levels (Beibu Gulf in Guangxi and the Leizhou Bay population in Zhanjiang); areas with insufficient site consideration and smaller designated ranges also require improvement in protection levels (Xiamen Bay population in Fujian and Shantou population in Guangdong). The methods and findings of this study can be applied globally to other dolphin populations, thus aiding in the assessment of protection levels in MPAs and thereby enhancing the overall effectiveness of conservation measures.

Chinese white dolphin,MaxEnt model,Marine protected areas