Age, growth, reproduction and mortality of <i>Xenocypris argentea</i> (Günther,1868) in the lower reaches of the Tangwang River, China.

Abstract

To investigate various population biological parameters of <i>Xenocypris argentea</i> in the lower reaches of the Tangwang River (China), a comprehensive study was conducted for the first time. A total of 1,003 samples were collected from April to November 2022. The collected samples revealed that female <i>X. argentea</i> had total lengths ranging from 12.4 cm to 25.7 cm (weighing 15.86 g to 159.55 g), and male <i>X. argentea</i> had total lengths ranging from 10.8 cm to 23.9 cm (weighing 9.27 g to 121.06 g). The age of the samples was determined using otolith analysis, indicating that the ages ranged from 1 to 5 years old in both females and males. The length-weight relationships were further analyzed, uncovering the allometric growth index (<i>b</i>) was 3.1296 for females, indicating a positive allometric growth pattern. Differently, males exhibited a <i>b</i> value of 3.0274, suggesting an isometric growth pattern. Furthermore, the von Bertalanffy growth formula provided insights into the growth characteristics of <i>X. argentea</i>, revealing an asymptotic total length (<i>L</i>_∞) of 36.096 cm and a growth coefficient (<i>K</i>) of 0.121. The analysis of the gonadal somatic index (<i>GSI</i>) and ovarian development period indicated that the spawning period occurred from April to July, with peak spawning in June. The study also explored fecundity-related traits, finding that individual absolute fecundity (<i>F_A</i>) ranged from 11,364 eggs to 56,377 eggs, while eviscerated body weight relative fecundity (<i>F_W</i>) ranged from 209 eggs/g to 823 eggs/g. The exploitation rate (<i>E</i>) for <i>X. argentea</i> was calculated as 0.574, suggesting that the population of <i>X. argentea</i> has been overexploited. By revealing previously unknown data on the key life history traits of <i>X. argentea</i>, this study has provided valuable insights that are crucial for the development of conservation strategies and policies.