Study On Age, Growth, Reproduction And Feeding Habit Of Carassius Auratus Gibelio In Irtysh River

From April to October 2013, 546 Carassius auratus gibelio samples were collected in main channel of the Irtysh River, Xinjiang. Through the comparison of four age determination structures, the analysis of the growth, reproduction and feeding habits, the basical biology of C. gibelio was studied. The main results were as follows:1.The age determination results of the same observer both time showed as follows. The sort of average percentage of error(IAPE) was otolith(1.89%) < vertebra(3.01%) < scale(3.27%) < operculcum(4.47%). The sort of agreement rate was otolith(91.9%) > vertebra(82.1%) > scale(81.2%) > operculcum(60.9%). Age appraisal deviation chart indicated the variability of age identification results from otolith was the lowest, agreement rate of otolith kept the high level in each age. The other materials kept high level of agreement rate from first age to third age, but agreement rate was low in elderly individuals. The agreement rate between scale and otolith was higher than that in operculum, and the same result also existed in vertebra. The average percentage of error of three materials compared with otolith revealed the value was higher in operculum than other two kinds of materials. Scale and vertebra can be used to identify young individuals age, but not suitable for older individuals. Operculum was not suitable for both young and older individual, was not recommended as C. gibelio age determination materials.2.The sex ratio for C. gibelio was ♀:♂=10.84:1, the range of weight was 1.12~ 1171.63 g, the average was 404.21±178.11 g, most individuals distributed in the sort of 250~600g. The range of standard length was 33~328mm, the average was 206.8±36.55 mm, most individuals distributed in the sort of 170~240mm. The age consisted of 9 groups, of which the number of the fourth age was the largest, accounted for 47.11%; the second large age group was 3 accounting for 30.17%.3. The relationship beween weight and standard length was W=2.661×10-5SL3.085(R2=0.96, n=546).The relationship between otolith dimensions and fish length and age were high.The growth equations were: Lt=359.7(1-e-0.172(t+1.066)), Wt=2042.3(1-e-0.172(t+1.066)) 3.085. The inflexion point for the age was 5.49, and the standard length and weight were respectively 243.2 mm and 610.81 g at the inflexion point.4.Though Logistic regression analysis, the estimated value of first sexual maturity length(L50) and age(A50) were 161 mm and 2.3 age for females and 135 mm and 1.9 age for males, respectively. The absolute fecundity of C. gibelio was 11850~187419(42453±28205) eggs, and the relative fecundity was 32.5~32.5(98.19±34.6) eggs/g. According to the histological characteristics of the gonad, the development of gonad can be divided into six periods. The absolute fecundity had a linear relationship with body length, power function relationship with weight, but with no significant correlation between age and ovary weight. According to the proportion of gonad of different development stage, gonadosomatic index variation and egg diameter distribution in different month, it can be speculated that the type of C. gibelio spawn was synchronous in the Irtysh river, and spawning during May to July, reached the peak in June.5.The jejunum rate of C. gibelio during April and May maintain a higher level, the lowest value occured in September. The food of C. gibelio mainly included diatoms, chironomidae, aquatic plant detritus. The aquatic plant detritus was the primary bait because of the higest weight percentage and dominance index than others.The improved Costello graphic method showed the same result. C. gibelio has the significant difference of the food composition in different season(P<0.05), but no significant difference of the food composition in different length group(P>0.05).