Assessing the impact of the proposed Poyang lake hydraulic project on the Yangtze finless porpoise and its calves

Abstract

The Yangtze finless porpoise has become as significant indicator of current ecological conservation effectiveness in Poyang Lake, where nearly half of the population is found. Serious water shortages in the lake during the dry season has led the government to consider the establishment of a hydraulic project (PLHP) in order to remedy the deteriorating situation. However, the possible impacts of the PLHP on porpoise habitats is uncertain since the distribution of porpoise habitats during the dry season has not been sufficiently studied. Here, we combine hydrodynamic and species distribution models to simulate likely habitat and nursing area variations with or without PLHP during the dry season. Results indicate that flow velocity and distance to sand mining areas dominate the habitat preferences of the porpoise and its calves, respectively. Habitats were concentrated in the narrow channel of the Lake, which includes an area less than 10% of the lake inundation area. Under the operation of PLHP, the nursing area will increase, and the habitat will increase during September to December, but decrease during January to February. However, their proportion of the lake inundation area will decreased by 0.5% to 1.6%, and the distribution pattern will become more discontinuous. Our results suggest that the PLHP may not substantially benefit the porpoise, as it will block the only natural migration channel between Poyang Lake and the Yangtze River.