Hatch Dates And Growth Of Larval Schizothorax Lissolabiatus In The Lancang River Based On Otolith Microstructure

Schizothorax lissolabiatus was analyzed for revealing the essence of growth and spawning time,And the purpose of this research further explore the daptability of plateau environment and draw up the protection strategies of S.lissolabiatus.The experimental part of this paper was studied by means of cology.From 2014 to 2016,the larval S.lissolabiatus was sampled,and the experiment contains the otolith microstructure analysis,larval growth and the age distribution.The age was determined by the hatching dates.The main indings are as follows:1.In the early growth process of S.lissolabiatus,the otoliths were initially early round and it grew slowly into a slightly pointed ellipse later.Under the transmitted light,the daily patterns consisted of a light slip and a dark slip,that grow around the center.The first few rings are usually narrow,and the otolith circles are round.2.There is a highly significant linear relationship between the total length and the otolith radius.The specific formula is:TL=79.097 OR+6.6885（p<0.001）.There is also a very significant exponential relationship between body weight and otolith radius.Formula:W=0.0048e^{13.067 OR}（p<0.001）;3.Based on the sampling time of the larvae and the age of the sample,the spawning period of the S.lissolabiatus in Lancang River is as follows,and the parental fish spawned that occurs in winter.In this research,the minimum age of the 205 specimens were 8,the fishing time was November 4,2016,and the maximum age was 70,the fishing time was March 1,2015.Then we calculated the spawning time of the parental fish by the accumulative temperature eduction algorithm.The spawning time in spring cohorts was March 7 at the earliest and April 3 at the latest.The incubation time in winter cohorts was the earliest on October 4 and the latest was January 23 on the second year.The ower limit of spawning temperature was 7.19°C,and the lower limit of water elevation was 1394.71m.4.In winter,the width of the otolith increment was significantly smaller than that of the spring cohorts（F=506.37>F crit）.The width of the daily ring gradually decreased with the increase of ordinal number.The spring cohorts was first widened with increasing number of rounds,reaching a maximum around 15rounds,and the width of the daily ring remained relatively stable later.5.There was a significant difference in the growth rate of cohorts collected in winter and spring（p<0.05）,and the growth rate of spring cohorts was significantly faster than that of winter cohorts.These basic research is of great significance for the further discussion on the adaptability of the fish to the plateau environment and the influence of ydropower construction.