Age, growth, reproduction and status of resource development of Ptychidio jordani, a critically endangered freshwater fish in the Hongshui River, China

The age, growth, reproduction and resource development status of Ptychidio jordani, as a critically endangered freshwater fish in the Hongshui River, China, was studied in this work. A total of 525 specimens were collected monthly using the cages and gillnets from October 2021 to September 2022 in the Hongshui River. The scale was used for age determination, and the maximum age for both female and male was estimated to be 5 years and 3 years, respectively. Female and male P. jordani showed different growth patterns, which were expressed as L-t = 261.3 (1-e(-0.4885(t-0.1476))) and L-t = 251.2 (1-e(- 0.4758(t+0.9643))), respectively. The overall sex ratio was 1:0.47 (female:male). Female attained sex maturity at 2.34 years (192 mm body length). Month variation of the gonad somatic index indicated that the spawning period occurred from April to October. The absolute fecundity was estimated at 9046 +/- 3434 eggs per individual, and the relative fecundity was 38.08 +/- 15.77 eggs per gram. The exploitation rate of female and male was 0.233 and 0.495, which indicated that P. jordani was not overfishing. This study pro-vided data on the key life-history traits of P. jordani, which has not been known previ-ously and is essential for conservation strategy and policy development.

Automated summary

This study investigated the age, growth, reproduction, and resource development status of the critically endangered freshwater fish Ptychidio jordani in the Hongshui River, China. A total of 525 specimens were collected monthly from October 2021 to September 2022. The study provided data on key life-history traits of P. jordani, including age determination, growth patterns, sex ratio, sexual maturity, spawning period, fecundity, and exploitation rate. These findings are important for conservation strategies and policy development.