THE GROWTH CHARACTERISTICS OF LIOBAGRUS STYANI IN STREAMS OF SOUTHERN JIANGSU PROVINCE

Studying the age structure and growth characteristics of fish not only elaborates the basis of biological research, but also has important significance for the conservation and restoration of fish germplasm resources. Liobagrus styani has been reported to distribute in the middle and lower reaches of the Yangtze River. But there is no detailed report on its distribution. Based on the first discovery for its distribution in Jiangsu Province by the fishery resource survey, it is urgent to study the basic biological characteristics of L. styani. A total of 221 L. styani were collected from streams of Southern Jiangsu Province using handheld pulse sampling device from January 2017 to April 2019, and 105 L. styani were released into the streams. The age structure of L. styani was analyzed with the vertebrae identification. The relative growth rate, instantaneous growth rate, growth constant, growth index were calculated. The results showed that the L. styani vertebrae were irregular, and the annual vertebrae rings clearly stained with alizarin red dye liquor. The age of L. styani ranged from 1 to 5 years, and the fishes between 2 to 3 years were dominant, accounting for 71.85%. Their average length and weight were (72.64±9.15) mm and (5.88±2.25) g, respectively. The fitting equation of the relationship between the length (L) and the external diameter of vertebra (R) was L=22.134R+34.551, and the fitted relationship between the weight (W) and length (L) was W = 3×10^–5L^2.836. The von Bertalanffy growth equations of the L. styani were L_t=108.45 1–e^{–0.1330 (t+3.8058)} and W_t=17.74 1–e^{–0.1330 (t+3.8058)2.836}, respectively. The inflexion age of growth was 4.04 a, and the corresponding length and weight were 70.22 mm and 5.17 g, respectively. It can be inferred that when facing high fishing intensity, it was easier to show signs of resource reduction than other fish in streams, and the recovery time of population resources was longer. This study has important value to give reference for protection and resource recovery of L. styani.