| Jinshaia sinensis Sauvage et Dabry, formerly known as Hemimzon sinensis, was cypriniformes, homalopteridae, Jinshaia. It was omnivorous fish, and an endemic species of fish in the upper reaches of the Yangtze River, it was representative in the fish taxa.In this study, the samples of J. sinensis, which had been collected in December2011to October2012in the main stream of Yangtze River of Yibin, Sichuan province, were studied about their feeding habits and growth, and the results were as follows.1. The mouth of J. sinensis was slightly curved, and the width of its mouth gradually increased with the body length increasing, and there was a significant difference among different groups of body length; the length of intestine also increased with body length increasing, but the intestinal coefficient stayed at around2stably, after the body length reached more than7cm. For all the catches, the average intestinal coefficient was1.93±0.54, which indicated that they were omnivorous fish;2.The feeding intensity of J. sinensis was the highest in autumn and lowest in summer; the food basically consisted of algae, arthropods, rotifers, aquatic oligochaetes, debris of the aquatic higher plants, snails and protozoa; Among them, the algae was mainly composed of bacillariophyta and chlorophyta; the arthropods were only composed of three species:chironomid larvae, perlidae and cyzicidae; in winter and spring, the highest frequency of occurrence was algae, followed by arthropods; But in the autumn, there was no algae in food, the highest frequency of occurrence was arthropods. And arthropods kept a high rate of occurrence in all seasons. It showed that J. sinensis feed the arthropodas preferentially when the arthropoda food was sufficient. But when the arthropoda food was not sufficient, they feed the algae as a supplement. 3.The average body length of the catches of J. sinensis in the section of the Yangtze River in Yibin was8.23cm, and was concentrated in8～10cm; The average body weight was10.39g,and was concentrated in9～17g. The related expressions of body length and body weight was:W=0.0204L2.9159,(n=167, R2=0.9259)4. The catches of J. sinensis were1～6years old. The4years old catches were the most, accounting for54.62%of the all. Asteriscus, scale and spine, were all suitable to age determination. But in the advanced age individuals, the age of scale was less than the age of asteriscus and spine. The lapillus and sagittal weren’t suitable to age determination. The correlation between asteriscus radius and body length was better than the correlation between scale radius and body length. So, the asteriscus radius was good for back-calculated body length. And the related expressions of body length and the asteriscus radius was:L=21.825R+0.3799(n=149, R2=0.7225;L:cm, R:mm).5. According to the back-calculated body length, the asymptotic length (L∞) was19.60cm and asymptotic weight (W∞) was119.54g. So the von Bertalanffy equations of J. sinensis were as follows:The von Bertalanffy equation about body length:Lt=19.60[1-e-0.1156(t+1.764)];The von Bertalanffy equation about weight:Wt=119.54[1-e-0.1156(t+1.3764)2.9159.The growth speed and acceleration were determined by taking first derivative and second derivative of the von Bertalanffy equation of body length and weight. By the way, it has been shown that there was no inflection point of the growth speed and acceleration of body length, but the growth speed and acceleration of weight did. At the inflection point, the age is7.88years, the weight is35.12g and the body length is12.88cm. |
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