Community structure of ichthyoplankton and its relationship with environmental factors in Daiquyang spawning ground

The ichthyoplankton net was used to carry out the survey of fish eggs and larvae of Daiquyang between May 2010 and February 2012. According to the investigation results, 1 042 fish eggs and 2 055 fish larvae were collected, which belonged to 10 orders 19 families 37species. The dominant species of fish eggs were Auxis thazard and Eupleurogrammus muticus while fish larvae were Liza haematocheilus, Engraulis japonicas and Stolephorus chinensis. The average density of fish eggs in the surveyed areas was 8.40 ind./100 m³ while fish larvae was 14.85 ind./100 m³. The results of One-Way ANOVA showed that there were highly significant differences among the diversity index (H′) in 4 seasons of spring and summer from 2010 to 2011, so were in the evenness index (J′) and richness index (D). The CPUE of fish eggs and larvae showed uneven distribution, it was higher in spring and summer, but lowest in winter, which revealed that fish eggs and larvae resource density demonstrated a tendency of higher in the south stations and lower in the north stations. Pearson correlation analysis proved that the environmental factors most closely related to fish eggs and larvae were temperature, salinity and suspended matter. The results suggested that spring and summer were important seasons for fish spawning and Daiquyang areas were important spawning and nursery grounds for pelagic fishes such as E. japonicas, A. thazard and S. chinensis.