GROWTH AND REPRODUCTIVE CHARACTERISTICS OF ACROSSOCHEILUS MONTICOLA IN THE CHISHUI RIVER AND THEIR CHANGES AFTER THE TEN-YEAR FISHING BAN

In 2017, the Chishui River basin became the first to enforce the complete fishing ban, serving as a pilot demonstration area for the subsequent ten-year fishing ban on the Yangtze River. Research on fish growth and reproductive traits after the fishing ban provides a scientific basis for evaluating the fishing ban efficacy and guiding population conservation. This study examined the growth and reproductive characteristics of Acrossocheilus monticola, an endemic species of the upper Yangtze River, in the Chishui River from March 2023 to June 2025. We compared our results with those of the pre-fishing ban (2014—2017) to examine how the fishing ban affected fish growthand reproductive traits. A total of 426 A. monticola specimens were collected, with 419 aged. The female-to-male ratio was 1:0.52. The length-weight relationships for female and male fish were W_♀=2.219×10^–5L^3.001 and W_♂=2.008×10^–5L^3.019, respectively, indicating isometric growth. Specimens ranged in age from 1 to 6 years. Maximum longevity was 6 years for females and 4 years for males. The asymptotic length and weight for females were 282.6 mm and 503.9 g, with k=0.129 and theoretical age at zero length (t₀)= –2.476. For males, the asymptotic length and weight were 255.0 mm and 369.9 g, with k= 0.160 and theoretical age at zero length (t₀)= –1.946. A. monticola appears to be a batch spawner, with a mean absolute fecundity of 3, 092±1, 223 eggs. Mean relative fecundity was 21.2±8.4 eggs/mm and 46.8±18.9 eggs/g relative to body length and body weight, respectively. Relative to the pre-fish ban period, the dominant length class shifted from 100—120 mm to 120—160 mm, and the dominant weight class from 0—40 g to 20—80 g. Maximum observed age increased from 4 to 6 years, while absolute fecundity rose by 71.9%. These findings indicate that the fishing ban has contributed to improvements in the growth and reproduction and population structure of A. monticola in the Chishui River. To promote fish resource conservation in the Chishui River, We suggested continuing the complete fishing ban after the 10-year moratorium expires. Concurrently, habitat protection and restoration should be strengthened, and long-term monitoring should be conducted on fish biology, population dynamics, and habitat conditions.