Exploring key drivers of Chinese sturgeon spawning sites fragmentation in the Yangtze River: Insights into spawning window

Abstract

Since 1950, the Yangtze River has experienced significant human interventions, resulting in various environmental changes, including alterations to fish habitats and the gradual retreat and disappearance of the Chinese sturgeon's wide distribution range. In this study, an evaluation framework was proposed to evaluate the reasons that led to the reduction or even disappearance of spawning activities. Three historical spawning sites and one current spawning site of Chinese sturgeon in the Yangtze River were studied. According to the time of human activity, three periods were proposed: pre-dam (1950–1981), post-dam (1982–2002), and post-impoundment (2003−2020) periods. Human activities affect fish habitat use and spawning timing. The simulation results indicated that habitat degradation was a reason for the disappearance of the historical spawning sites of Chinese sturgeon, in which the hydrodynamic conditions that did not meet the spawning requirements being the main reason for the disappearance of spawning activities. Narrowed spawning period and delayed spawning activities resulted in the disappearance of spawning activities in the current spawning sites. The evaluation framework provided in this study has been demonstrated to be reasonable and practical for fish habitat assessment in dammed rivers. It can be used to evaluate the effects of future construction of hydraulic projects for better reservoir regulation and fish conservation.