Identifying the seasonal characteristics of likely habitats for the Yangtze finless porpoise in Poyang Lake

Abstract

Abstract The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) has experienced significant decline and habitat degradation in recent decades. At present, nearly half of the total population inhabits Poyang Lake. The hydrological seasonality of the lake significantly influences porpoise habitat configuration, which brings problems for conservation in the delineation of reserve design and the management of human activities. A hydrodynamic model was used to distinguish the different hydrological conditions between the flood and dry seasons. The MaxEnt model was used to investigate the major environmental variables affecting porpoise distribution and delineate likely habitats of the porpoise under different hydrological conditions. The effectiveness of the present nature reserve was evaluated based on these results. Flow velocity and distance to fish spawning grounds were the primary variables influencing porpoise distribution during the dry season. Water depth, flow velocity and the distance to bank were the major variables during the flood season. The likely habitats were distributed discontinuously along the main channel during the dry season, with a total area of 112 km2. During the flood season, the habitats extended into the central areas of the lake and tributaries with a total area of 628 km2. At present, the nature reserve covers 4% and 18% of the likely core habitats during dry and flood seasons. An ideal nature reserve should be designed as an integrative network with reference to the seasonality of likely habitat distribution and major environmental variables. The habitats in conditions of extreme low water should be strictly protected in the dry season. Enhanced survey efforts, long‐term hydrodynamic modelling and species distribution modelling can greatly assist in understanding habitat configuration and changing processes for other freshwater cetaceans inhabiting river–lake systems. Future planning to improve protection should consider habitat characteristics under the shifting hydrological conditions caused by climate change or artificial flow alteration.