Study On Genetic Resources And Artificial Breeding And Culturing Techniques Of Nibea Japonica

Artificial breeding Technique and Culturing technique in Cage of Nibea japonic were studied in this paper,and temperature tolerance and the comparative Genetic Resources between Nibea japonica and Nibea miichthioide were also studied.The reseach results are as follows:16 Nibea japonica parent fishes naturaly reproduced 1.45×106 good eggs after artificial increase to get sexual matured. 1.20×106 larvaes are hatched from 1.45×106 fertilized eggs, the hatching rate was 82.8%. The water temperature ranged from16.8℃to 24.6℃and salinity ranged from 23.2 to 29.9, the oxygen ranged from 5.7 mg/L to 7.8 mg/L during the experiment. After 48 days, 6.48×105 yong fishies were reared, with average total length 4.1㎝ and survival rate 54.0%.Cage farming of Nibea japonica experiment was carried out in the Shuangyu Bay of Liuheng Zhoushan, including designning of the cage and culturing managments。The following works were systematic studied and summarized,including the characteristics of feeding, growing, diseases and disease prevention of Nibea japonica.This study will be helpful in the popularizing of culturing of Nibea japonica。Two hundreds of Nibea japonica had experimented to endure hingh and low temperature,also abserved Nibea japonica feeding and swimming capability at high and low temperature.Result showed that the highest resistance temperature was 34℃, the lowest resistance temperature was 8℃,The safe over- wintering temperature was 10℃, the feeding temperature is 10～32℃of Nibea japonica.Partial sequence of cytochrome b gene in Nibea japonica and Nibea miichthioides were amplified using PCR technology. The products of PCR were sequenced directly and 1137 bp of Cyt b gene were obtained. Compare obtained sequences, the comparability of two sequences is 98.82 %. Information of the base composition and the mutation sites were got. The difference of two sequences was obviously and there were 2 codon positions could be used to identify the two species. The Cytb gene was a molecular marker for identify in species. All the results offered the genetic data for making good use of the two species.As important economic marine fish,Nibea japonica and Nibea miichthioides are similar in morphological characters, which are easily influenced by the geographical regions and environments. Therefore, it is usually difficult to distinguish them accurately by morphological level,and then investigating the genetic differences becomes necessary.the random amplified polymorphic DNA(RAPD) technique is the wildly used method in species identification process.Sixteen polymorphic random primers were selected from 120 Operon's primers to amplification purposes.The results showed that the average genetic similarity index within two species is 0.8853 in N.japonica and 0.8901 in N. miichthioides.The variances of average genetic similarity between individuals within each species were detected by SPSS software.There was significant difference (P<0.05)among the species of N.miichthioides and no such character among the species of N.japonica. The genetic distance between the two species was 0.2150 indicating the N.japonica and N. miichthioides belong to two different species, respectively.