RESEARCH STATUS OF EARLY FISH RESOURCES IN SHIJIU LAKE DURING THE BAN ON FISHING AND THEIR RELATIONSHIP WITH ENVIRONMENTAL FACTORS

In order to understand the status quo and environmental impact factors of early fish resources in Shijiu Lake, a daily survey was carried out from May 9, 2023 to August 9, 2023. A total of 14251 juvenile fish were collected, and 39species of fish belonging to 9 orders and 10 families were identified. Among these, the Cyprinidae family was the most diverse, comprising 27species and accounting for 69.23% of the total species identified. There were 5 dominant species, including Rhinogobius giurinus, Hemiculter bleekeri, Hemiculter leucisculus, Neosalanx tangkahkeii, and Pseudolaubuca sinensis. The fish community was predominantly composed of small-sized species, which accounted for 56.41% of the total species. According to the spawning type, there were 23species with the largest number of demersal eggs, accounting for 58.97% of the total species, and 12394 individuals accounting for 86.97% of the total. Temporal analysis revealed 5 distinct density peaks, with the highest peak occurring on May 13 (548 ind./100 m³). The final peak, observed on 30 July reached 365 ind./100 m³, after which juvenile density began to fluctuate and decrease. Spatially, the average juvenile density was 108 ind./100 m³ on the north shore and 79 ind./100 m³ on the south bank. However, there was no significant difference in the juvenile density on the south bank, the middle line of the river channel, and the north bank (P>0.05). Redundancy analysis (RDA) showed that water temperature, water level, dissolved oxygen, and transparency were strongly correlated with juvenile density. The results of this study fill the gap in the research of early fish resources in Shijiu Lake, and can provide a scientific basis for the conservation and ecological restoration of fish resources in Tongjiang Lake.