Study On Age,Growth,Reproduction And Feeding Habits Of Cultrichthys Erythropterus In Dianchi Lake

940 samples of Cultrichthys erythropterus in Dianchi Lake were collected in July,August,December 2013 and from February to June 2014.We studied on the age,growth,reproduction and feeding habits of C.erythropterus,compared with other research results,to provide theoretical support for the management of fishery resources of C.erythropterus in Dianchi Lake,the study results as follows:1.We observed four age materials of otolith,scale,cleithrum,operculum.The otolith showed obvious ring characteristics under the age of 4 and showed the obvious ring characteristics above the age of 4 after grinding.The otolith had the highest coincidence rate of 98.2%,followed by the scale(91.7%),the cleithrum(66.5%)and the operculum(59.8%)in two age reading results by one observer.The otolith had the lowest average coefficient of variation of 0.5%,followed by the scale(2.1%),the cleithrum(10.7%)and the operculum(13.4%).The rate of the ability to discriminate of the age were 100% of otolith,followed by followed by the scale(98.7%),the cleithrum(97.3%)and the operculum(90%),the coincidence rate of scale was 98.2%,followed by the cleithrum(66.5%)and the operculum(59.8%)based on otolith.In short,the otolith was the most suitable age material of C.erythropterus,scale effect is inferior to otolith,the cleithrum and the operculum were not suitable for age identification of C.erythropterus in Dianchi Lake.2.The standard length of C.erythropterus ranged from 42 mm to 267 mm and the advantage body length ranged from 70 mm to 160 mm,accounted for 83.6%.The body weight ranged from 0.5 g to 329.1 g and the advantage body weight below 40 g,accounted for 73.8%.The fitted equation of body length and weight were: female:W=7.001×10-6SL3.136,male :W=8.912×10-6SL3.073,undefined:W=5.154×10-6SL2.908;The fitted equation of body length von Bertalanffy were: female:Lt=316.6(1-e-0.200(t+0.7362)),male : Lt =299.6(1-e-0.250(t+0.5925))and body weight von Bertalanffy were: female: Wt =486.1(1-e-0.200(t+0.7362))3.136,male: Wt =363.4(1-e-0.250(t+0.5925))3.073.The age at inflection point of female was 4.9 and the body length and weight at this point was 214.1 mm and 142.5 g.The age at infection point of male was 3.8 the body length and weight was 145.6 mm and 39.6 g at this point.3.The sex ratio of C.erythropterus was 1.78:1,the male had the advantage over female under the body length of 100mm(0.86:1),the female had the advantage over male above the body length of 100mm(2.27:1).The age and length of sexual maturity was 2.0 and 88.7 mm for female and was 1.3 and 69.1 mm for male.The breeding time of C.erythropterus was from April to August and egg size ranged from 0.5 mm to 1.6 mm.The counted individual ranged from 111 mm to 238 mm for body length and ranged from 20.7 g to 214.1 g for body length.The absolute fecundity ranged from 2100 to 51996 eggs(11488±9636 eggs),the relative fecundity ranged from 86.1to 352.3 eggs/g(202.9±73.8 eggs/g).The equation was F=0.006SL2.826 for relationship between absolute fecundity and body length and F=198.5GW-1762.8 for relationship between absolute fecundity and body weight.4.The minimum vacuity index of C.erythropterus was in June and the maximum was in March,which indicates that it had a higher feeding intensity during breeding period.C.erythropterus had wide range of food items,but the most important food based on relative importance coefficient was Daphnia(30.76%),followed by shrimp(14.22%),Bosmina(13.35%)and small fish(12.20%)..The feeding habits varied among different size of body length and different seasons,but was similar between male and female.In summary,the reason why C.erythropterus became dominant was attributed to its specific reproductive strategy.The population of C.erythropterus should be controlled because it mainly feed on large zooplankton and was unfavorable for controlling phytoplankton.