Effect Evaluation On Stock Enhancement Of Trachinotus Ovatus Based On Molecular Markers And Genetic Characterization Of Three Marine Fishes For Stock Enhancement

In present study, mitochondrial DNA control and microsatellite DNA markers were used to estimate the effect of the stock enhancement of Trachinotus ovatus which is an important stock enhancement species. In addition the superiority-inferiority of both the molecular markers were comparative analyzed. Variation in the mitochondrial DNA transcriptional control region sequence was investigated in hatchery-released and wild populations of three stock enhancement species (T. ovatus, Acanthopagrus schlegelii, Pagrus major) in order to monitor the genetic effects of releasing large number of ooreleasing juveniles. The main results are presented as follows. (A) Effect evaluation on stock enhancement of Trachinotus ovatus based on molecular markers30 juveniles when they cultivated in the hatchery and 55 recaptured individuals were collected. Microsatellite DNA loci together with nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used as genetic tags, and we compared the properties of the two molecular markers in tracking the released pompano. For mitochondrial DNA maker, the analysis showed that 7 mtDNA haplotypes were observed in 45 of the 55 T.ovatus recaptured individuals, which were also shared by T.ovatus juveniles. For microsatellite maker,23 of the 55 are not the survivors of released T.ovatus. Tracking the released pompano analysis showed 26 of the 55 T.ovatus recaptured individuals are the survivors of released T.ovatus based on the method of combing the two molecular markers, accounted for 47.27% of the recaptured individuals. As expected, microsatellite maker are more efficient than mitochondrial DNA maker, which can be dominant marker in case of dealing with massive samples. (B) Genetic characterization of three marine fishes for stock enhancement(1) To examine the present population genetic diversity and variability of T.ovatus, a 517-bp hypervariable fragment of mtDNA control region was sequenced. A total of 131 individuals from 2 wild,1 hatchery-released and 1 cultured populations were analyzed. The genetic diversity of hatchery-released populations (h=0.795; π=0.018; k=9.301) which was obviously higher than that of the cultured populations (h=0.670;π=0.011;k=5.406), was slightly less than that of the wild populations (h=0.863-0.924; π=0.018-0.019; k=9.011-9.595). No significant genealogical branches or clusters corresponding to sampling localities were detected by UPGMA tree. Pairwise Fst and AMOVA revealed that no significant genetic differentiation mainly existed among hatchery-released population and wild populations.(2) To examine the present population genetic diversity and variability of A.schlegelii, a 486-bp hypervariable fragment of mtDNA control region was sequenced. A total of 112 individuals from 3 wild and 1 hatchery-released populations were analyzed. The genetic diversity of hatchery-released populations(h=0.920; π=0.009;k=4.294) was slightly less than that of the wild populations (h=0.946-0.986; π=0.010-0.011;k=4.804-5.208). Pairwise Fst and AMOVA revealed that no significant genetic differentiation mainly existed among hatchery-released population and wild populations.(3) To examine the present population genetic diversity and variability of P.major, a 431-bp hypervariable fragment of mtDNA control region was sequenced. A total of 86 individuals from 2 wild and 1 hatchery-released populations were analyzed. The genetic diversity of hatchery-released populations (h=0.918; π=0.026;k=11.553) was slightly less than that of the wild populations (h=0.987-1.000;π=0.030-0.034; k=13.427-15.718). Pairwise Fst and AMOVA revealed that no significant genetic differentiation mainly existed among hatchery-released population and wild populations.