Studies On Several Culture Biology Characteristics Of Salmo Trutta

Salmo trutta which belongs to Salmoniformes, Salmonidae, is only distributed in Yadong River, Tibet, China. In this study, with Salmo trutta and Salmo trutta as objects,breeding biology and molecular biology were analyzed. It can provide the theory basis for the sustainable artificial breeding and protection of germplasm resources species.The genetic structure and diversity of Salmo trutta and Salmo trutta fario L. were studied with 8 polymorphic microsatellite locis. Mitochondrial DNA D-Loop sequences were used to analysis the system evolution and genetic relationship in the study. The results showed that the number of alleles at each locus in two populations ranged from two to ten and four to nine, respectively. The average number of effec-tive alleles was3.1304 and 3.8988. The observed heterozygosity varied from 0.3404 to 0.7128 and0.1020 to 0.8776, respectively. The expected heterozygosity was 0.4671~0.7794 and0.5216 ~ 0.7932.The polymorphic information content(PIC) of Salmo trutta ranged from 0.3680~0.7440, with an average of 0.5964. And the PIC of Salmo trutta fario L.varied from 0.466 to 0.837, with an average of 0.5926.The results indicated that two populations have rich polymorphism information content and large genetic diversity.Salmo trutta and Salmo trutta fario L. have the closest relationshio with Atlantic phylogenetic lineages.The objective of the study presented was to determine the effects of different stocking density on the growth and survival of Salmo trutta fry at two months age.Experimental fish were reared at five different stocking densities, 400, 600, 800, 1 000 and 1 200 individuals per tank. Over the experimental period of 49 days, the weight of Salmo trutta fry went up from 0.14 g to 1g, the results showed that stocking density had insignificant effects on the survival rate and condition factor. The final body, daily weight gain, specific growth rate and weight growth efficiency of fry were decreased with the increase of stocking densities, among those, daily weight gain decreased significantly from(0.018±0.001)g to(0.013±0.001)g. The result showed that stocking density had negative effects on growth. However, net yield was increased with the increase of stocking densities, and there were significant differences between the low and high densities groups(P<0.05). The fry of Salmo trutta reared in different densities grew in allometry, but the stocking density had insignificant effect on the variation ingrowth.Nutritional compositions in muscle of brown trout Salmo trutta fario were analyzed by routine methods and evaluated by amino acids score(AAS) and chemical score(CS).The results showed that the fresh muscle contained moisture of 70.81%, crude protein22.63%, crude fat 4.91% and crude ash 1.80%. There were total amino acid(TAA) of 69.51%, total essential amino acid(EAA) 28.86% and total delicious amino acid(DAA) 26.09% in dry muscle with EAA/TAA of 41.52%and EAA/NEAA of84.11%. It was clear that the two ratios in the muscle were in accord with the standard of FAO/WHO(40%, and 60%). The AAS and CS revealed that methionine+cystineandthe and valine were the limited amino acids, with essential amino acids index(EAAI) of 85.54. A total of 12 kinds of fatty acids were detected in the muscle of the brown trout, including 19.76% of saturated fatty acid(SFA), 38.32%of monounsaturated fatty acid(MUFA), 38.98% of polyunsaturzted fatty acid(PUFA),and up to 12.31% of total content of EPA and DHA. In conclusion, brown trout is one of the fish with good nutritive value and culture values.