Diel distribution, migration and abundance assessment of Toxabramis houdermeri in Baise Reservoir, China

The split-beam hydro-acoustics surveys were conducted to learn about the diel migration and distribution characters of Toxabramis houdermeri and to assess its current abundance in Baise Reservoir of China in October 2013. The study revealed the average density of T. houdermeri was 258 individuals/1000 m(3), and gradually increased from downstream, through middle to upstream (203 individuals/1000 m(3), 252 individuals/1000 m(3) and 318 individuals/1000 m(3), respectively). The study also showed that the target species always distributed in the 2-42 in water layer during the daytime, before migrating upward around dusk which led the fish density to sit in the 2-12 m water layer, to reaching a peak value of 1740 individuals/1000 m(3) during the night. Finally, the fish volume density was found to positively correlate with the concentration of chlorophyll, dissolved oxygen (DO) and pH value in their studied areas. In conclusion, the results presented that T houdermeri preferred a relatively higher average chlorophyll concentration of 3.58 ug/L DO of 6.33 mg/L, and pH of 7.96 in the upstream and upper layers of Baise Reservoir.