Study On Biology Of Triplophysa Bombifrons In Cheerchen River,Xinjiang

Cheerchen River is an important tributary in the lower reaches of the Tarim River,which eventually merges into Lake Taitma.The ecological status of the river is directly related to the comprehensive management of the Tarim River Basin.The population of Triplophysa bombifrons has declined sharply in recent years,and was listed as a critically endangered species in the Red List of protected animals in 2015.Finding out the biological characteristics in Cheerchen River Triplophysa bombifrons Loach can provide a basis for its protection.For this reason,5 sampling points will be set up in the upper,middle and lower reaches in Cheerchen River in the summer and autumn of 2019 and2020 and the spring of 2021.Sampling investigations were carried out.A total of 240loach were collected from the plateau,and the biological characteristics of their age,growth,reproduction,and feeding habits were analyzed and studied.The main findings are as follows:（1）The age structure of Triplophysa bombifrons.Otoliths and operculum are used for age identification.Compared with operculum,otoliths have higher clarity and anastomosis rate.They are suitable age identification materials for Triplophysa bombifrons The age range of Triplophysa bombifrons is 1～6 years old,3～4 years old is the dominant agegroup,accounting for 57%of the overall proportion,1st and 6th years accounting for the smallest proportion,14%,female individual age composition structure and male individual minor difference.（2）The growth characteristics of Triplophysa bombifrons.The relationship between the body length（SL）and weight（W）of Triplophysa bombifrons is related by a power function,and there are significant differences between males and females.Female individual:W=0.00561×SL^2.9967;male individual:W=0.00803×SL^2.8743.The relational expressions of von Bertalanffygrowth equation are:female fish:Lt=23.54[1-e^{-0.4121（t+0.3420）}],Wt=74.49[1-e^{-0.4780（t+0.3213）}]^2.9967;malefish:Lt=24.01[1-e^{-0.4780（t+0.3213）}],Wt=91.49[1-e^{-0.4121（t+0.3420）}]^2.8743.The inflection point ages of female and malegrowth are 3.2 years and 3.8 years,and the corresponding body length and weight are 17.1 cm,24.3 g and 19.0 cm,35.38 g,respectively.（3）The reproductive characteristics of Triplophysa bombifrons.The overall female-male ratio of the Loach population on Triplophysa bombifrons is 0.45:1,and the female-male ratio will vary with seasons and body length.The age and individual size of females at first sexual maturity are 1.3 years and 14.0 cm;the age and individual size of males at first sexual maturity are 1.8 years and 15.1 cm.The breeding period is from May to July,and the spawning type is synchronized spawning.The absolute fecundity is20105.8-35696.1 grains;the relative fecundity is 3630-4360grains/g.The egg diameter of stage III and above in the breeding period ranges from 0.3 to 0.9 mm,and the spawninggrounds are distributed in quiet water depressions in the middle and lower reaches.The spawning environment is soft sandy bottom.The spawning time is from May to late July.The peak period of spawning is mid-to-late May,and the suitable spawning temperature is about 20°C.（4）Feeding characteristics of Triplophysa bombifrons.The feeding intensity of Triplophysa bombifrons in Cheerchen River is the highest in June,and it is lower in September and October.Food composition analysis showed that the food composition in Cheerchen River Triplophysa bombifrons is dominated by benthic animals and aquatic insects,while a small amount of algae and plant debris are occasionally present.The analysis of the percentage of individuals,the percentage of weight,the percentage of occurrence rate and the relative importance index shows that the main food for Triplophysa bombifrons in Cheerchen River is the bottom sacrificial animal,followed by the chironomid larvae,and the food composition varies with body length,season and It varies bygender.When the body length is less than 10 cm,the main food is aquatic plants,cladocerans,and copepods;when the body length is between 10 and 20 cm,the main food is benthic animals and chironomid larvae;when the body length isgreater than 20 cm,the main food is Small fish and aquatic insects.The food diversity index is the highest in summer（2.17）and the lowest in winter（1.26）,and the food overlap index is small（less than 0.6）.