SPATIAL AND TEMPORAL DISTRIBUTIONS OF FISH LARVAE AND JUVENILES IN LAKE WULI, LAKE TAIHU

To explore the scale and distribution characteristics of fish larvae and juveniles, a systematic investigation was conducted in Lake Wuli from April to October 2016. A total of 70678 larvae and juveniles were collected, and 20 species of larvae and juveniles from 18 genera, 8 families, and 7 orders were recorded. The density of annual average larvae and juveniles in Lake Wuli was 3825 ind./100 m³, and Hemiculter sp. was dominant throughout the year. Based on the temporal density variation, the spawning period in Lake Wuli lasted from April to August, and the peak spawning month was June. The dominant species changed monthly: the earliest were Cyprinus carpio and Carassius auratusatus (April), and the latest was Salangichthys sp. (August to September). Significant spatial differences in the distribution of larvae and juveniles were observed in Lake Wuli. The density of larvae and juveniles in the coastal zone was significantly higher than that in the pelagic zone, with densities of 5650 ind./100 m³ and 310 ind./100 m³, respectively. The density in eastern Wuli Lake was lower than that in the west, with densities of 3600 ind./100 m³ and 4482 ind./100 m³, respectively. Canonical correspondence analysis indicated that water temperature (WT), dissolved oxygen (DO), and phytoplankton and zooplankton abundances were strongly correlated with the distribution characteristics of larvae and juveniles. The study showed that in Lake Wuli, the main breeding period of fish is from April to August, and the main spawning and parenting waters are coastal belts. Additionally, the results determined that the breeding function of western Wuli Lake is better than that of eastern Lake Wuli. Therefore, further maintaining the habitat protection of western Lake Wuli, enhancing the vegetation restoration in the coastal area of eastern Wuli Lake, and improving water quality monitoring of the tributaries in the lake, and controlling the external pollutants are of great importance for habitat optimization and natural proliferation of fish resources in Wuli Lake.