Study On The Biology Of Gymnodiptychus Dybowskii Kessler In The Ili River

Gymnodiptychus dybowskii Kessler belongs to the genus of Gymnodiptychus, the subfamily ofSchizothoracinae, the family of Cyprinidae and the order of Cypriniformes. G. dybowskii is an endemicspecies in the Ili River of XinJiang. As a cold-water species and an important part of the aquatic ecosystemin the Ili River, G. dybowskii serves a vital ecological function in sustaining the biodiversity and ecologicalintegrity of endemic fish species. However, in recent years, the G. dybowskii population has beendecreasing in some tributaries in the Ili River. The major causes of fishery resource reduction areoverfishing, water pollution, and hydroelectric engineering. And this species has been listed in the Red Listof Threatened Species as a near threatened fish by the people’s government of the Sinkiang UygurAutonomous Region in2004. So421individuals were collected from the Ili River and its tributariesmonthly from March2013to May2014. The main results are as follows:1. The typical pattern with translucent zones, which was characterized by alternative wide zones andnarraw zones was found in otoliths, vertebrae and opercular bones of G. dybowskii. Annuli formed fromMarch to June once a year. Age identification results of three times the average IAPE was otoliths thelowest (1.19%), followed by vertebrae (1.31%), opercular bones is the highest (3.04%). We know theability of discriminant age material is: otoliths> vertebrae> opercular bones. Therefore, otoliths is the bestage identification of materials for G. dybowskii.2. The standard length (SL) of G. dybowskii ranged from46mm to383mm, and weight (W) ranged from0.8g to312.8g, and age ranged from0year to7year. From the otolith specifications with the correlationcoefficient between the length of fish/age, in addition to the relationship between otolith weight and bodylength coefficient of slightly higher, other otolith specifications with the variability of fish body length andage are big, naked heavy cold fish otolith specification (length, width, thickness and weight) for bodylength calculated age and appraisal indicators.The SL-BW relationship was described as W=1.017×10-5SL3.049for ensemble, W=3.926×10-5SL3.129for females, W=2.822×10-5SL3.036for males.The von Bertalanffy growth equations were L+0.949))t=312.0(1-e-0.155(t) and Wt=342.8(1-e-0.155(t+0.949))3.129for females, and Lt=287.4(1-e-0.173(t+0.873)) and Wt=307.9(1-e-0.173(t+0.873))3.036for males.The estimated inflection points were (ti)6.95years for female and (ti)5.80years for male, respectively.And the Aarent Gowth Idex () were4.178and4.155.3. The Ili River is composed of three tributaries, Kashi, Kunse and Tekes River. The standard length (SL)of G. dybowskii in Tekes River ranged from46mm to244mm, and weight (W) ranged from1.1g to201.0g, and age ranged from1year to6year. The standard length (SL) of G. dybowskii in Kashi River rangedfrom49mm to285mm, and weight (W) ranged from1.5g to214.2g, and age ranged from0year to6year.The standard length (SL) of G. dybowskii in Tekes River ranged from50mm to383mm, and weight (W)ranged from0.8g to312.8g, and age ranged from1year to7year.The SL-BW relationship in three reviers were described as W=2.852×10-5SL2.843(Tekes River), W=2.306×10-5SL2.892(Kashi River), W=7.614×10-6SL3.102(Kunes River).The von Bertalanffy growth equations were: Lt=284.3(1-e-0.139(t+0.559)) and W.559)t=295.9(1-e-0.139(t+0)2.843for Tekes River; Lt=289.2(1-e-0.158(t+0.604)) and Wt=302.5(1-e-0.158(t+0.604))2.892for Kashi River; Lt=310.2(1-e-0.165(t+0.693)) and Wt=371.1(1-e-0.165(t+0.693))3.102for Kunes River.The Aarent Gowth Idex () were4.130for Tekes River4.151for Kashi River and4.209for Kunes River.The relevance analysis showed that the regional difference of the growth of G. dybowskii was negativelycorrelated with altitude and flow velocity, but was positively correlated with water temperature and foodabundance.4. There is no shape difference between male and female except the spawing season. There are pearlorgans on rostral side, orbit vicinity and fin rays of males in spawning season. The female and male ratiowas1.14:1, which differed significantly from1:1(P <0.05). Gonads were assigned to six macroscopicmaturity stages. Based on the histological analysis, gonads were assigned to six microscopic maturitystages. Standard length, weight and age of the females at first maturity were139mm,31.2g and3.4years,respectively, and those of the males were102mm,14.1g and2.5years, respectively. The Standard length,weight and age of the females at smallest sexual were117mm,24.5g,and2years, respectively, and thoseof the males were101mm,19.7g and1years, respectively. G. dybowskii were single spawners with along-term spawning pattern from early April to late June. The fecundity ranged352~4210(3087±1081)eggs, and the relative fecundity ranged14.7~54.4(21.2±2.7)/g body weight. The fecundity increasedwith standard length and body weight, but had no significant correlations with ages (P <0.05). The growthof G. dybowskii was positively correlated with water temperature from7°C to15°C, and the velocity from0.2m/s to0.7m/s.5. The feeding intensity of G. dybowskii in Sinkiang and body length changes in significant difference (p<0.05). G. dybowskii is wide of predatory fish, fish recipes with wider, and with aquatic insects, algae areborne as main food. To adhere to the periphyton feed on the rocks, the feeding of digestive organs inhypertrophy lip and diets.