Studies On Genetic Breeding And Cultivation Techniques Of Pacific Abalone, Haliotis Discus Hannai Ino

Implementations of genetic improved varieties are fundamentals to agriculture. Looking back to the development of agriculture, genetic breeding together with cultivation techniques have brought great prosperities worldwide. However, the genetic breeding programs of aquatic organisms initiated recently, while researches on breeding techniques in aquaculture field are lacking in China. Establishment of genetic breeding system of marine animals should be based on the biological characteristics of objective animals and quantitative genetic models constructed in agricultural organisms.Pacific abalone, Haliotis discus hannai Ino is one of the most important mariculture species in northern China. Researches on gentic control of shell color, quantitative genetics relating to genetic improvement of Pacific abalone, and cultivation techniques on combined effects of sizes, stocking density and sorting on juvenile growths were reported in this study. The main results are listed as follows:1. Phenogenetics of mutant red-shelled Pacific abalone had been analyzed by controlled mating experiments between the orange-shelled abalone and the wild-type (green-shelled) ones. Varying diets feeding were conducted to orange shell colored Pacific abalones and the wild type ones to detect the diet impacts on Pacific abalone shell coloration. Besides, growth comparison between the two types in F2 families was also carried out.Controlled mating experiments were designed to observe the segregation of the F2 generation between the orange type (O-type) and the wild type (G-type). Results show that the O-type and G-type of shell coloration is controlled by a recessive (o) and a dominant allele (G) at a single locus in the Pacific abalone genome.To detect diet impacts on Pacific abalone shell coloration, varying diets feeding were conducted to O- and G-type individuals of Pacific abalone. Results show that although the orange and green genotypes are controlled at genetic level, diets may still cause some limited variations in shell colorations within individual phenotypic lines. O- or G-type abalones always had orange or dark-brown colors when supplied with diatoms or red algae, or turned into yellow or green when fed with brown or green algae, or an artificial diets purchased commercially. On the other hand, color shifting between types O and G would never occur, which permitted us to safely assign orange and yellow as the O phenotype and dark-brown and green as the G phenotype in the study. These observations further support the notion that the shell coloration in Pacific abalones is genetically controlled, but with unique patterns in response to the diet changes. The association of'diet– shell coloration'can be a morphological marker, which can be applied in the research of cultivation technique and genetic breeding in Pacific abalone, such as tagging individual or lines.All family lines occurring shell color segregation in F2 were selected and measured the shell lengths for 3-5 times for the juvenile abalones aged at 2-14 months. Among them, there were no significant differences in all groups of abalones between O and G-type juvenile abalones. It suggests that the O-type mutation has no effect on the growth of abalones. 2. Shell morphological indices analysis on selective and crossing stocks was conducted in Pacific abalone.Seven 4~6 year aged stocks, including four artificial selective stocks on growth rate and three hybrid stocks between wild geographic populations in Pacific abalone were used as materials. Shell length (L), shell width (W), shell height (H) and shell weight (Sw) were measured on 60 ~100 samples in each stock. L/(L+W+H),W/(L+W+H),H/(L+W+H) and Sw/(L×W×H) were calculated as shell morphological indices. Statistical methods of MANOVA and ANOVA were used to detect the significant differences in the shell morphological indices among the tested stocks. Results show that the CV (%) of the shell morphological indices are 0.34, 0.74, 2.62 and 6.54. Indices of H/(L+W+H) and Sw/(L×W×H) demonstrate high polymorphism and showed significant differences among the tested stocks, which indicated the high genetic variations. Owing to the unavailability of Sw/(L×W×H) in the practice, genetic improvement on shell shape can be selected on the index of H/(L+W+H)。 3.Genetic parameter estimates during adult stages of Pacific abaloneIt is necessary to estimate the genetic parameter estimates during adult stages of Pacific abalone to establish a scientific breeding system. Eight half-sib families and 21 full-sib families were obtained by a nested design. Heritabilitis of shell length at ages of 70-550d was 0.161 ~ 0.326 by sire component, and 0.312 ~ 0.977 by dam component. While, heritabilities of growth rate were 0.080 ~ 0.210 and 0.299-0.306 during 320-380 days and 490-550 days, respectively. The larger dam component estimation indicated the maternal effects still existed in the adult stages. The estimated genetic correlations between shell length at contiguous ages were consistently high, ranging from 0.597 ~ 1.000 to 0.589 ~ 1.177 by sire and dam components, respectively. Whereas, the estimated genetic correlation between growth rates at 2 phases was near 0. Because of the few sire parents in the experiment, standard errors to the genetic parameter estimated by sire component were large, however, the dam component estimation were all significantly greater than zero. The genetic correlation level between shell lengths at contiguous ages indicated the feasibility of early selection to the trait.4. Crossing evaluation between artificial selective groups in Pacific abalone16 crossing combinations by diallele cross between 4 artificial selective groups in pacific abalone, were established to compare the differences between the selective groups, investigate the magnitude of heterosis (mid-parent) and heterobeltiosis (better parent), and combination abilities at early stages.Additionally, a 2×2 factorial cross between Dalian"98"and Shantou"S"selective groups produced 4 groups to test heterosis in fertilization rate, hatching success, metamorphosis and growth at early stages. Juveniles of shell length >1.2cm from the 4 groups were treated at 3 temperatures to investigate the magnitude of heterosis on varying environments.(1) Significant differences in shell lengths at 9, 20 and 30d after fertilization between purebreds of the selective groups were detected. 97×97 performed worst in shell lengths at each stage (0.462±0.023mm, 0.698±0.057mm, 1.476±0.234mm), while S×S performed best in shell lengths at each stage (0.522±0.023mm, 0.824±0.084mm, 1.798±0.229mm).Heterosis and heterobeltiosis varied among shell length traits at stages of 9, 20 and 30d after fertilization. Out of the 12 crosses, six crosses showed significantly positive heterosis and three crosses exhibited significant positive heterobeltiosis in shell length at stage of 9d, with highest value of 9.05% in J×97, and 5.77% in S×J; seven crosses showed significantly positive heterosis and five crosses exhibited significant positive heterobeltiosis in shell length at stage of 9d, with highest value of 12.60% in J×97, and 12.20% in J×97; six crosses showed significantly positive heterosis and three crosses exhibited significant positive heterobeltiosis in shell length at stage of 9d, with highest value of 24.08% and 15.95% both in 97×S."S"group had the significant and largest GCA value, and 97×S had the positive, significant and largest SCA value. These indicated the possible application of 97×S as the super crossing combination. Reciprocal effects during the early stages also demonstrated. (2) Reciprocal crosses between two selective groups"98"and"S"were carried out, and mid-parent heterosis for fertilization rate, hatching rate, metamorphosis rate and growth were studied. Furthermore, juvenile growth of the 4 F1 groups generated was tested in 3 different temperatures. Results showed significant difference in eggs sizes between the selective groups. Heterosis for hatching success, metamorphosis and early growth were 5.49%, 12.53% and 0.936-1.534%, respectively. Heterosis for juvenile growth were obtained in the varying temperatures. Significant interaction between genotype and environment indicated heterosis were larger in the lower temperature environment. Higher single-parent heterosis to"S"group showed that crossbreeding can be an effective way to improve the growth performance of"S"groups. The present study validated the Lerner's (1954) theory.5. Studies on intermediate culture of juvenile Pacific abalone(1) Evaluation of juvenile over-wintering mode in southern ChinaA new juvenile over-wintering mode of Pacific abalone was examined. Juvenile abalones were transferred to the open seas in southern China to over-winter and growth and survival were compared between varying over-wintering modes in northern and southern China. Results show: a. growth and survival of juvenile abalones were significantly affected by initial body sizes in both cultivation modes. The survival rates were in a significant linear correlation with the initial sizes ranged from SL=10.59 to 18.37mm in the southern over-wintering mode (P<0.05). That suggested the necessity of early spawning or the application of genetic improved stain to improve the initial body sizes, for the sake of obtain higher survival rate during juvenile over-wintering. b. Juvenile growth and survival rates during over-wintering period in southern China were 81.37-108.89μm·day-1 and 91.38%, respectively. Growth rate during over-wintering in southern China increased 1.06 to 1.68 times compared to that in northern China, while no significant differences in survival rate were indicated. The superiorities of the southern over-wintering mode were in the growth performance and low-energy consuming. c. In southern over-wintering mode, juvenile mortality occurred in the initial adaptive period and periods of water temperate occurring larger fluctuations. That can indicate a guide to selection of the time of abalone over-wintering.(2) Evaluations of combined effects of initial sizes, stocking density and sorting on juvenile growths during over-wintering stagesInitial size, stocking density and sorting are among the first considerations when setting up abalone adult grow-out systems. This study aimed to investigate the effects of these factors on growth of over-wintering juvenile Pacific abalone, Haliotis discus hannai Ino cultured in southern China open waters. Juvenile abalones were reared in multi-tier basket form for over-wintering in the open sea environment of southern China for 106 days. Results indicated that DGRs and SGRs of juvenile abalones were significantly affected by initial body size and stocking density. Effects of density varied with the initial size. Sorting abalones may not be necessary in practice as sorting did alter growth significantly in all densities. Causes of the combined effects on abalone growth such as genetic control and intraspecific competition were discussed. The results of this study can be readily applied in over-wintering of juvenile abalones in southern China waters...