The impact of dams on the population viability of a migratory fish in the Yangtze River, China

Abstract

1. The global diversity of freshwater fish has been greatly reduced as a result of human alteration. In the Yangtze River, China, the species composition has changed hugely owing to dam construction and overfishing. However, insufficient data have prevented the status of several fish species being evaluated, including that of largemouth bronze gudgeon (Coreius guichenoti), which is a commercially important endemic species.2. This study describes the effects of the Xiangjia Dam on populations of C. guichenoti. A multivariate autoregressive state-space model was applied to catch per unit effort data derived from drifting gill nets deployed in the midchannel before (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) and after (2013-2018) the construction of the dam.3. The analysis indicated that the mean instantaneous population growth rate of the population was À0.252 over the entire period and that the growth rates of both total and local populations have declined. Before the impoundment, the probability of population extinction was close to 1, which was the result of overfishing. After impoundment, the probability of extinction became 1 at all sites, and the time until quasi-extinction has decreased. Based on the Euler-Lotka equation, the reproductive parameter (á) has declined by more than 95%.4. The results show that the population of C. guichenoti in the upper Yangtze is almost certain to become extinct under the current conditions because of the Xiangjiaba Dam blocking migration routes. To protect this population, conservation measures, such as hatchery supplementation, the removal of small hydropower stations in the tributaries and the relocation of fish, are required.

A review of conservation status of freshwater fish diversity in China

“…Additionally, the loss of lotic habitats along the mainstem has made it unlikely for drifting eggs laid by C. guichenoti to float with the water until they completely develop into larvae (Yang et al, 2017;Zhang et al, 2018). The larval resources of C. guichenoti in the mid-lower Jinsha-Jiang have exhibited a sharp decline over the past decade, with a 94.1% reduction in the total number of eggs and larvae (Gao et al, 2022;Lin et al, 2019;Yang et al, 2009Yang et al, , 2017. The building of dams across the affluents of Lake Dongting is also responsible for the extinction of rheophilic species like Onychostoma rarum, Procypris rabaudi, and Spinibarbus sinensis in the lake because their river-lake migration route has been blocked (Chen et al, 2022).…”

“…Coreius guichenoti , a potamodromous, rheophilic, benthic gudgeon, is under threat from river damming (Cheng et al, 2015; Yang et al, 2009). Owing to spawning ground loss and habitat shrinkage in the mid‐lower Jingsha‐Jiang mainstem, this fish has been forced to migrate upstream into tributaries like the Shuiluo‐He of northern Yunnan Province to spawn (Gao et al, 2022). Additionally, the loss of lotic habitats along the mainstem has made it unlikely for drifting eggs laid by C. guichenoti to float with the water until they completely develop into larvae (Yang et al, 2017; Zhang et al, 2018).…”