Prediction of suitable habitats for the Indo-Pacific humpback dolphin (Sousa chinensis) in the Beibu Gulf of China and Vietnam

Abstract

The Indo-Pacific humpback dolphin (Sousa chinensis) is a threatened coastal flagship species in Asian marine ecosystems, but the distribution of its suitable habitat remains unclear. In the present study, we characterized habitat relationships and predicted potential suitable habitats for humpback dolphins in the Beibu Gulf of China and Vietnam. Maximum entropy modeling identified six discontinuous areas in the Beibu Gulf, with a total area of 4396.8 km2, as suitable habitats for humpback dolphins. Of these, three suitable habitats covering 3948.8 km2 were known habitats, and three others covering an area of 448.1 km2 at the border of China and Vietnam or in Vietnamese waters (Beilun River Estuary, Qinghua, and Rongshi) were newly identified. Exploratory line-transect surveys are strongly recommended to determine whether dolphins are present in these three areas. The predicted suitable habitat showed seasonal variation, which increased slightly in the dry season compared with that in the wet season. Bathymetry is the most important predictor for habitat suitability, in line with the known coastal distribution of humpback dolphins. Our research predicted specific suitable habitat distributions, which can be used to develop practical protection measures, such as the establishment of marine protected areas for this species to monitor, mitigate, or prohibit harmful anthropogenic activities.

The first baleen whale marine protected area proposed for Bryde's whales in the Beibu Gulf, China

“…However, the Beibu Gulf is also a prominent economic zone with urbanized coastlines, busy harbors, and fishing grounds (Koongolla et al, 2020; Lin et al, 2021). These anthropogenic activities have strong negative impacts on marine species and seriously threaten the survival of inshore corals, economically important fish, and cetaceans (Long et al, 2022; Wu et al, 2021). For example, the individual injury rate of Bryde's whales in the Beibu Gulf due to entanglement and ship strikes has increased in recent years (Wu, Jiang, et al, 2020; authors' unpublished data).…”