Research on catchable size and resource protection of Squaliobarbus curriculus in Xijiang River Fengkai section based on length-frequency data

We conducted an eight-month catch survey in 2014 and collected 526 individuals of Squaliobarbus curriculus. Based on their body length and mass, we estimated the biological stock characteristics (growth and mortality parameters) and assessed the stock size and status of S. curriculus. The length-mass relationship was fitted by a power function (a=0.028 8, b=2.858 2). The von Bertalanffy growth parameters were estimated: the asymptotic length L_inf was 74 cm; the growth coefficient K was 0.1; the natural mortality coefficient M was 0.19; the total mortality coefficient Z was 1.51; the fishing mortality rate was as 1.32; the exploitation rate was 0.88. In 2014, the size of the stock in numbers and biomass were 2 234 652 individuals and 428.558 t, respectively. Results of the yield per recruit (YPR) modeling shows that the current length at first capture was 12.3 cm; the fishing mortality rate was 1.32; the current YPR was 1.89 g. When the length at first capture was 27.8 cm and the fishing mortality rate was 0.45, the YPR was 7.76. The current stocks of S. curriculus have been over-exploited. It is suggested that the length at first capture should be 27.8 cm, and the fishing mortality rate should be 0.45.