[Heritability of body weight and fork length for Oncorhynchus masou masou].

Body weight and body length have been considered as the most important production traits for the fish genetic improvement. For cold-water fish, body length was usually substituted by fork length. In order to estimate the heritability of body weight and fork length of the sixth generation Oncorhynchus masou masou, which was introduced into China, the method of unbalanced nest design and an artificial insemination technigue were used. Twenty-nine full-sib families and fourteen half-sib families were obtained. Body weight and fork length of O. masou masou were measured in 12 and 24 months after fertilization. Based on full-sib and half-sib families data, the causal components of phenotypic variance were calculated. The results showed that, (1) during the whole growth phase of O. masou masou, the coefficient variation (CV) of fork length was higher than body weight, and CV of 12-month old was higher than that of 24-month old; (2) body weight and fork length of O. masou masou among sires and dams among sires were significant difference (P<0.01) both at 12 months and at 24 months; (3) the maternal component estimates were significantly larger than those of paternal ones for body weight and fork length traits both at 12 months and at 24 months; (4) for 12 months of O. masou masou the heritabilities of body weight and fork length were 0.41~0.51 and 0.46~0.54, respectively. For 24 months the values were 0.55~0.60 and 0.53~0.59, respectively; and (5) it was concluded that the heritability of growth traits in O. masou masou was relatively high and this highlights the potential to improve its growth through selective breeding. This study shows important data supporting for further genetic improvement of O. masou masou.

Population genetic analysis of aquaculture salmonid populations in China using a 57K rainbow trout SNP array.

Various salmonid species are cultivated in cold water aquaculture. However, due to limited genomic data resources, specific high-throughput genotyping tools are not available to many of the salmonid species. In this study, a 57K single nucleotide polymorphism (SNP) array for rainbow trout (Oncorhynchus mykiss) was utilized to detect polymorphisms in seven salmonid species, including Hucho taimen, Oncorhynchus masou, Salvelinus fontinalis, Brachymystax lenok, Salvelinus leucomaenis, O. kisutch, and O. mykiss. The number of polymorphic markers per population ranged from 3,844 (O. kisutch) to 53,734 (O. mykiss), indicating that the rainbow trout SNP array was applicable as a universal genotyping tool for other salmonid species. Among the six other salmonid populations from four genera, 28,882 SNPs were shared, whereas 525 SNPs were polymorphic in all four genera. The genetic diversity and population relationships of the seven salmonid species were studied by principal component analysis (PCA). The phylogenetic relationships among populations were analyzed using the maximum likelihood method, which indicated that the shared SNP markers provide reliable genomic information for population genetic analyses in common aquaculture salmonid fishes. Furthermore, this obtained genomic information may be applicable for population genetic evaluation, marker-assisted breeding, and propagative parent selection in fry production.

The complete mitochondrial genome sequence of white-spotted char (Salvelinus leucomaenis).

The complete sequence of the mitochondrial genome of the white-spotted char (Salvelinus leucomaenis) was determined to be 16,658 bp in length, which contains the control region (CR), the origin of light-strand replication (OL), 22 transfer RNA genes, 2 ribosomal genes and 13 protein-coding genes. Overall, base composition of the complete mitochondrial DNA was 28.20% A, 26.51% T, 28.39% C, 16.90% G, with 54.71% AT.

[Optimal feeding strategy for juvenile Hucho taimen].

Three experiments including starvation and re-feeding, starvation and re-feeding recovery, and feeding frequency per day were conducted to approach the optimal feeding strategy for the growth and survival of juvenile Hucho taimen. In the experiment of starvation and re-feeding, all groups of restricted feeding showed non-compensatory growth. However, in the experiment of starvation and re-feeding recovery, different degrees of compensatory growth appeared in different starving groups, among which, the half a day starvation and half a day feeding group (S1/2) had a weight increment approximately the same as the control, and showed completely compensatory growth, indicating that the S1/2 could be a useful feeding strategy for the juvenile H. taimen at its early growth stage with the body mass from 0 to 2 g and at the water temperature from 9 to 15.3 degrees C. In feeding frequency experiment, the group T3 (three meals per day) had the highest body length, body mass, specific growth rate, and relatively high food conversion ratio, indicating that three meals a day could be more effective for improving the growth performance of juvenile H. taimen at its late stage with the body mass from 2 to 21 g and at the water temperature from 8.8 to 15.5 degrees C.