REPRODUCTION TIME AND MAIN INFLUENCING FACTORS OF SCHIZOTHORAX PRENANTI IN THE MIDDLE REACHES OF THE DADU RIVER

In order to understand the natural spawning pattern of Schizothorax prenanti, we calculated the hatching period of S. prenanti larvae and juveniles collected from the middle reaches of the Dadu River from 2012 to 2014. The spawning period of the parent fish was determined by integrating the accumulated temperature required for fertilized egg development. Additionally, we conducted an analysis of the correlation between hydrological factors and their spawning activity. The results showed that the incubation accumulated temperature for fertilized eggs of S. prenanti under artificial breeding conditions was 1467.36℃·h. The hatching time for collected juvenile fish spanned from 30th November to 19th April of the following year, and the estimated spawning time is from November 8th to April 11th of the following year. The peak spawning period occurred from early January to mid-March. Correlation analysis revealed a negative association between the reproductive activities of parent fish and various factors, including flow, water temperature, air temperature, precipitation, sediment concentration and water level (P<0.05). The spawning time of parent fish and the hatching time of larvae predominantly coincided with the dry season from November to April characterized by low flow, water temperature, water level, precipitation and sediment concentration. Notably, frequent or more concentrated flow fluctuations appeared to better stimulate the spawning activities of S. prenanti. These results provide basic data for comprehending the reproductive patterns of the wild S. prenanti population and contribute to the formulation of resource protection measures.