Early development of Sinogastromyzon wui and its resource supplement in the lower reaches of Liujiang River

【Objective】 In order to provide basic data for the resource assessment and sustainable utilization of Sinogastromyzon wui in the lower reaches of Liujiang River,the study observed early development of S. wui and evaluated its resource in the lower reaches of Liujiang River.【Method】 Fish larvaland fish eggs were collected in Shilong Town,lower reaches of the Liujiang River from May 16 to August 31,2017. In this study,the collected eggs were artificially cultivated,and the morphological changes of the larvae were observed and described in detail. The resource supplement of S. wui in the lower reaches of the Liujiang River was estimated by setting a cross section.【Result】 The shape of the fertilized eggs of the fish were ovate with monolayer and yellow colour,which was 4.50±0.10 mm in diameter. The total length of the newly hatched larvae was 5.00±0.21 mm,with 35 pairs of muscle segments 3+20+12. Meanwhile eye pigment and pectoral fin primordia appeared,the heart rate was about 165 times/min and the body was pale yellow with hemispherical spotty pigment distribution in the front part of the yolk sac.Anal fin,pectoral fin and abdominal fin were basically formed and the development of the larvae stage was completed in 25 d after hatching. The total length was 18.50±0.35 mm,and the body was light red. During the investigation period,the distribution coefficient in the sampling section of the lower reaches of the Liujiang River was 0.416 and the resources replenishment of S. wui was estimated to be 2.48×10⁸ eggs during the sampling period in Liujiang River. The Spearman correlation analysis showed that,the density of fish eggs was negatively related to the discharge,and water level significantly(r=-0.688,P<0.01;r=-0.663,P<0.01),while it had significant positive correlation with transparency and the dissolved oxygen(r=0.667,P<0.01;r=0.297,P<0.01).【Conclusion】 Compared with Balitoridae,the length of S. wui is small and its eggs are non-viscous drifting eggs. The spawning of S. wui is significantly negatively correlated with discharge and water level,and significantly positively correlated with transparency and dissolved oxygen. Therefore,the population resource supplement of S. wui in the lower reaches of Liujiang River may decrease after the completion of the Datengxia Reservoir.