Spatio-temporal Distribution Patterns And Growth Characteristic Of Neosalanx Taihuensis In Wuqiangxi Reservoir

We have conducted a dynamic investigation among6sampling sites in Wuqiangxi reservoir in the period of May,2011to June,2012. Our purpose is to find out the diversity food organism, spatio-temporal distribution patterns and growth characteristic of Neosalanx taihuensis. The main results were as follows:1.The results showed that in the investigating period61kind of zooplankton were tally found with protozoa9, rotifer a26, cladocera10and copepod16, the forms and the preponderant species were different in different seasons. The average quantity of zooplankton in each seasons was133.48ind/L, the maximum quantity appeared in summer (341.24ind/L). The average biomass was4.36mg/L, the maximum biomass appeared in autumn (9.03mg/L). The zooplankton diversity index were2.09-3.17. It showed that the zooplankton community of Wuqiangxi reservoir in a stable state, and it was found that the water quality of the Wuqiangxi reservoir belonged to the ecological light-medium pollution type. The water quality were detected by chemical analysis method. According to the comprehensive trophic level index TLI(TP), the values of Wuqiangxi reservoir were between83to95, and he comprehensive trophic level index TLI(TN), the values of Wuqiangxi reservoir were between54to74. It showed that the river was in a eutrophication level. The results showed that the water quality of Wuqiangxi reservoir is bad by chemical and biochemical evaluation.2. The number of Neosalanx taihuensis is rich in resources before the breeding season, it dropped sharply in breeding season, and it rebounded after the breeding season. The distribution of Neosalanx taihuensis exhibited certain changes by the changes of time. The largest number of spring groups fish in September, the smallest number in April; the largest number of the autumn groups in February, small number. in November. The Neosalanx taihuensis distributed widely throughout the year, the spring groups and the autumn groups in the incidence rate of88.68%at the six sampling points, but the spatial distribution patterns is uneven. The resources at non-breeding area is rich than the cage culture area. That It showed that the fish resource development and distribution is related its breeding, and related to human factors. In order to achieve the sustainable use of fishery resources, we should make measures to protect the fish’s spawning grounds and. reduce human disturbance.3.Analysis indicates that its month age suits to von-Bertalanffy growth formula. The equations are:the spring-stock W=0.0034L3.0272(n=538,r=0.9566), the autumn group W=0.0017L3.3791(n=590,r=0.9585). The results suggested that the fish was isometric velocity growth type. And by the growth formula, the growth rate formula and accelerative growth rate formula of lody length and lody weight was deduced out. Growth point of inflection sites at5.77month age of the spring-stock, while the growth point of inflection sites at3.97month age of the autumn group. Through researched the growth regularity of the Neosalanx taihuensis, and combining with its growth characteristics, reservoir ecological characteristics, it confirmed the suitable fishing period is proposed to be September to October.