Comparative Studies On Morphology,Culture Performance And Biochemical Composition Among Yangtze,Huang, And Liao River Populations Of Adult Eriocheir Sinensis Reared In Ponds

The Chinese mitten crab Eriocheir sinensis is one of the important aquaculture species in China. The main culture areas are located in the river basins of Liao, Huang and Yangtze. E.sinensis and the local geographical populations were wiedly used in aquaculture in their respective area. However, it is unclear whether there are any differences in morphological characters, culture performance, gonadal development and biochemical compositions for the pond-reared Liao, Huang and Yangtze populations, which would hinder the further exploration amd utilization of their genetic resources. Therefore, this study was conducted to compare the morphology, gonadal development, culture performance and nutritional composition among Yangtze, Huang, and Liao River populations of wild juvenile Eriocheir sinensis cultured in earth ponds, which would provide theoretical basis and value information for the utilization and selective breedings of this species.1. Based on the morphological measurement, this study was conducted to measure and compare the morphology of adult Eriocheir sinensis among Yangtze, Huang, and Liao River populations when the wild juveniles are cultured under the similar pond conditions. The results showed that:(1) Significant differences were observed in morphological characteristics among three populations, including 7 and 17 morphological indices for female and male crabs, respectively. However, their coefficient of variation did not reach the threshold value for the subspecies.(2) There were 5 and 7 of dominated principal component for female and male crabs, respectively, and 4 to 5 indices were further selected to establish discriminant equation; expect for the male crabs of Huang River population, those equations had less than 75% of accuracy for distingushing three populations.(3) Cluster analysis showed that the male crabs from the Yangtze and Huang populations were pooled into one group, while the male crabs from Liao population were divided into another group; and the female crabs of three populations were pooled into one group.(4) Therefore, no significant differences were found in the morphology of adult crabs among three populations, which might be related to their growth environment.2. This study was further conducted to compare the gonadal development and culture performance among Yangtze, Huang and Liao River populations of wild juveniles E. Sinensis reared in earth ponds. The results are shown as the following:(1) Both female and male, the mean body weight of Yangtze population was significant higher than that of the other two populations in November(P <0.05). The male of Huang River population had significant higher body weight gain rate(WGR) and specific growth rate(SGR) than those of Liao River popultion during the period of March-May(P <0.05), while, the male of Yangtze population had significant higher body weight gain rate(WGR) and specific growth rate(SGR) than those of Liao River popultion during the mid-late culture stage(P <0.05). The female of Liao River population had significant lower body weight gain rate(WGR) and specific growth rate(SGR) than those of the other popultions during the period of March-May(P <0.05), while, the female of Liao population had significant higher body weight gain rate(WGR) and specific growth rate(SGR) than those of the other popultions during May-July(P <0.05).(2) There were significant differences in the speed of gonadal development among three populations(P <0.05); the Liao River population had the highest GSI while Yangtze population had the lowest GSI among three populations.(3) Yangtze population had the significant higher final mean body weight than the other two populations, and Yangtze population had the significant higher percentage of large size crabs, leading to the highest yeild among three populations. Huang River population had the lowest survival among, but there were no significant differences among three populations(P >0.05). In conclusion, there were significant differences in the gonadal development and culture performance of wild juveniles Eriocheir sinensis among three populations. Yangtze population had the best culture performance. Yangtze population had the slowest speed of gonadal development among three populations, while the fastest gonadal development was found on Liao River population.3. The final chapter was conducted to compare the nutritional composition of adult E. Sinensis among Yangtze, Huang and Liao River populations reared earth ponds. The results are shown as the following:(1) Yangtze population had the higher HSI, MY, TEY and RF than the other two populations. However, there were no significant differences in these indicators among three populations(P >0.05).(2) Three populations had the similar proximate composition for each edible part. However, the protein content in gonad of male from Liao River population was significantly higher than that of the other two populations(P<0.05), Yangtze population female had the significant higher ash content in hepatopancreas and muscle than the other two populations(P <0.05).(3) Three population had the similar fatty acid composition in the edible part. Huang River population male had the significantly higher levels of C18:3n3(LNA) and C20:5n3(EPA) than the Liao River population(P<0.05), Yangtze population had the significantly higher percentage of C22:6n3(DHA) among three populations(P<0.05).(4) The gonad of Liao River population male had the significantly higher contents of methionine and cystine than the other two populations(P<0.05), and the highest contents of the total essential amino acid(∑EAA), total nonessential amino acid(∑NEAA) and total amino acid(TAA) were also found in gonad of Liao River population; the muscle of Yangtze population had the highest ∑ EAA, ∑ NEAA, TAA contents among three populations. The ovaries of Yangtze population had the significantly higher contents of phenylalanine, tyrosine, tryptophan, aspartic acid and serine than Liao River populations(P<0.05); for the amino acid contents in the muscle, Huang River population had the highest contents for most amino acids, leading to the significant higher total amino acid(TAA) than that of the other two populations(P <0.05).(5) Only in male, Lysine, Valine and Tryptophan were the limited amino acids in the gonad of Liao River population. And, Liao River population had the lowest mean essential amino acid score(EAAS) of gonad and muscle among the three popluations.In conclusion, the adult E. Sinensis had no significant differences among three populations of wild juveniles cultured in the similar pond conditions, but Yangtze population had the better culture performance than the other populations while Liao population had the fastest gonadal development among three populations. Although no significant differences was found on the proxiamte composition among three populations, significant differences were observed on the composition of some fatty acids and amino acids among three populations, which maybe related to genetic factors or gonadal development stages.