[Morphological and quality difference of adult Anguilla japonica under three aquaculture models]

Anguilla japonica adults with a snout-vent length of (25.91 +/- 3.26) cm were randomly sampled from the ponds of monoculture A. japonica (M1) and polyculture A. japonica and Macrobrachium nipponense (M2) and the proliferation site in reservoir (M3) to compare the morphological and quality indices of the adults under the three aquaculture models. Discriminant analysis, cluster analysis, and factor analysis were applied to reveal the differences among the individuals of these three cultured populations. Among the test 21 biological traits and 23 morphological and quality indices, there were significant differences in 15 biological traits and 14 morphological and quality indices between M1 and M2, 19 and 18 between M1 and M3, and 11 and 8 between M2 and M3, respectively. The Euclidean distance between M1 and M2, M1 and M3, and M2 and M3 was 1.433, 3. 516, and 2. 167, respectively, and the differences were significant. The accumulative variance percentage of the first five principal components was 82.1%, and the eigenvalues of these components were all larger than 1. The principal components 1 and 2 could be regarded as fatness factor and movement factor, the other three principal components could be regarded as well-being factor, and the three populations could be clearly separated each other by principal component 1. In discriminant analysis, the five principal components, i. e., body width / anal length, body length / anal length, net volume coefficient, swim bladder coefficient, and liver coefficient, were served as independent variables to establish discriminant functions of the populations, which could clearly distinguish the populations, with the discriminant accuracy and synthetic discriminant accuracy being 100%.