THE COMMUNITY CHARACTERISTICS OF LARVAE AND JUVENILE FISH IN THE ANQING SECTION OF THE YANGTZE RIVER

Anqing section is one of the important fishery resources waters in the lower reaches of the Yangtze River. To understand assemblage characteristics of larvae and juveniles fish and their correlation with environmental factors, the early fish resources in Anqing section were investigated day by day from April 17 to August 15, 2016. The results revealed that a total of 92160 larvae or juveniles were captured, and 90457 were identified, belonging to 7 orders, 13 families and 49 species, while Cyprinidae was the largest family including 32 species, accounting for 90.16% of the total number of tails; Gobiidae was the second largest family including 3 species, accounting for 5.71% of the total number of tails. As for ecological type and spawning type, fishery residents fishes and fishes with pelagic eggs accounted for the largest proportions of 87.57% and 88.30%, respectively. Hemiculter bleekeri (44.53%) was the largest dominant species in this section and the other dominant species were Hemiculter leucisculus (14.21%), Xenocypris argentea (8.11%), Rhinogobius giurinus (5.60%), Pseudolaubuca sinensis (4.75%), Pseudobrama simoni (4.13%), Pseudolaubuca engraulis (4.50%), Parabramis pekinensis (2.63%), Coilia nasus (1.89%) and Hypophthalmichthys molitrix (1.57%). Larvae or juveniles abundances have four obvious outbreak period with the first period on the 1^st May and the other three in the mid to late June, which were 1127.00, 1608.44, 1568.44, 1202.94 ind./100 m³, respectively. Redundancy analysis (RDA) revealed that the main environmental factors affecting the abundance of larval and juvenile fish in Anqing river section are water flow, water level and transparency (P<0.05). The abundance of most larval and juvenile fish were negatively correlated with water flow and water level, and positively correlated with transparency, which may explain by the excessive water flow and water level in that year. This study demonstrated that Anqing section was abundant of diverse species of early fish resources which mainly consisted of small fish, and the proportion of economic juvenile fish is small. These results provide basic information for the formulation of protection policy on Anqing fishery resources with scientific reference.