Coilia nasus, which is a non-native fish species in the upper reaches of the Yangtze River, has the basic biological characteristics such as broad feeding habit, great reproductive potential, and strong environmental adaptability. Since C. nasus appeared in the Three Gorges Reservoir region, C. nasus has spread rapidly, and formed a stable population. Up to now, C. nasus has become a dominant fish species in the Three Gorges Reservoir region. In order to explore the mortality characteristics and future development trends of the C. nasus population in the Three Gorges Reservoir area, 251 C. nasus samples were collected from the Wanzhou, Fengdu, and Fuling sections of the upper Yangtze River mainstream between June and November 2023. The weighted linear regression method and Chapman-Robson method were used to estimate the instantaneous total mortality rate, while the Natural Mortality Tool (NMT) was applied to estimate the instantaneous natural mortality rate. The life history parameters analysis results show that the maximum capture age of the C. nasus population in the investigation area was 7 year-old. The overall Von Bertalanffy equation for the population was L_t=42.09[1-e^{-0.156(t+1.46)}]. The total sex ratio of females to males was 0.93:1 (♀:♂). The mortality characteristics results showed that the instantaneous total mortality rate of the existing C. nasus population in the Three Gorges Reservoir area ranged from 0.54 to 0.56 a^-1, and the instantaneous natural mortality rate was 0.38 a^-1. Thus, the corresponding instantaneous fishing mortality rate ranged from 0.16 to 0.18 a^-1. Compared with data from other waters of the Yangtze River basin before the comprehensive fishing ban, these instantaneous mortality parameters of the C. nasus population in the Three Gorges Reservoir area were at historically low levels, indicating that the population is growing. Given the low instantaneous natural mortality rates and the favorable ecological environment after the fishing ban, we speculate that the population size and distribution range of C. nasus may continue to expand further in the upper reaches of the Yangtze River. Generally, the instantaneous mortality rate, as a pivotal parameter for quantifying population decline, represented a critical component in fisheries resource survey and assessment. In addition, accurate estimation of the instantaneous mortality rate could provide the essential foundation for assessing population dynamics and evaluating potential risks associated with invasive species. Therefore, the results of the present study have supplied the fundamental data for formulating effective management strategies for wild C. nasus fishery resources in the Three Gorges Reservoir region.