Acoustic monitoring on fish resources in Xijiangsection of Peard Riverduring first closed fishing season

Closed fishing season was initially implemented in Pearl River in 2011. We used a Simrad EY60 echo-sounder with 120 kHz split-beam transducer to survey the Xijiangsection of Pearl River. The results show that during the closed season, the density of fish resources was increasing, and the average fish densities were 0.051 3 indm-3 and 0.106 8 indm-3 in 2010 and 2011, respectively. According to the data of catches, the increases were deduced as follows: Megalobramaterminalis 47.85%, Squaliobarbus curriculus 18.54%, Cirrhina moitorella 10.87% and Parabramis pekinensis 6.25%. The deep water had higher fish density than shallow water, especially that fish obviously aggregated in concave region. The fish mainly distributed atdepth of 4~10 m. The implementation of closed fishing season, tosome extent, protectsbreeding of spawning stocks and supplementsfish resources as well as maintenancesnatural growth of fishes.