Morphometrics Analysis On Mylopharyngodon Piceus, Cteopharyngodon Idellus, Hypoplthalmichthys Molitrix, Aristichthys Modbilis In The Poyang Lake System

Poyang Lake, located in Jiangxi Province, is the largest freshwater lake in China and one of the two lakes still linked with the Yangtze River. The Lake is seated at the convergence of five rivers in Jiangxi Province, such as Ganjiang River, Fuhe River, Raohe River and Xiuhe River, and plays an important role in regulating water in the Yangtze River by providing water through Hukou County. As the unique junction connecting with Yangtze River, Hukou waters is the idea site to study some river-lake migratory fishes. Black carp, grass carp, silver carp, variegated carp are 'four major-home fishes'in fresh water. A large number of home fishes fry pour into the Poyang Lake through Hukou of the Yangtze River, inhabit and propogate as well in the Yangzte River and the Poyang Lake each year.According to the records, there are deme populations of the four major home fishes in the'five river', which is easy to conclude:there maybe occurred local lake sedentariae populations of the four family fishes in the water system of Poyang Lake, and due to differences of environment, they will possibly form local populations. The research analyzed the possibility of large morphological differatiation among the populations of the four family fishes in the water system of Poyang Lake through the methods of Discriminant Analysis, Clustering Analysis and Principal Component Analysis. If negation, the four family fishes in the water system of Poyang Lake were subling Changjiang population; against, there maybe occurred local populations of the four family fishes in the water system of Poyang Lake. We can draw some conclusions as follows according the experimental data:1.223 specimens of Grass carp were collected from 6 different localities. The results of the three multivariate mophometric analysis showed that the 6 Grass carp populations can be divided. The Ganjiang, close to Raohe and Xinjiang, was significantly different from Fuhe and Xiuhe population.2.154 specimens of Silver carp were collected from 5 different localities. The results of the three multivariate mophometric analysis showed that the 5 Silver carp populations can be divided. The Ganjiang and Fuhe, Xinjiang and Yangtze were close respectively; Xiuhe population was in a middle condition.3.152 specimens of variegated carp were collected from 5 different localities. The results of the three multivariate mophometric analysis showed that the Ganjiang was closest to Yangtze population; Xinjiang was significantly different from other 4 populations.4.83 specimens of Black carp were collected from 3 different localities. The results of the three multivariate mophometric analysis showed that the 3 Black carp populations are significantly different respectively.5. The multiple discrimination ratios among'the four major home fishes'were: black carp> silver carp> variegated carp> grass carp.6. The method of factor analysis of variance was used to indicate that many charaters among populations have occurred large morphological differatiation, which illustrates:the number of charaters having occurred more and more mophometric differatiation was increasing. The research also inferred that the different populations may become different subspecies after many years.