Studies On Reproduction And Breeding Key Technology Of Oncorhynchus Mykiss

King trout or golden rainbow trout（Oncorhynchus mykiss）was one of the earliestcultivated fish, dating back to19century,with its original habitat along the Pacificcoast of North America. With its rich nutritious elements and less fishy taste, severaldifferent strains of Rainbow trout has been domesticated, suitable for intensivecultivation and are recommended worldwide by FAO. Golden trout is a variety ofrainbow trout, with ornamental value because of its golden color, besides its nutritionvalue. Nowadays, rainbow trout supply falls short of demand in China, and import ofAtlantic salmon is needed every year to meet the market demand. The reason whyChina is in short of trout is that rainbow trout belongs to cold water fishes, which limitsits range of geographical cultivation, and only north and north west of China have coldwater resources with plateau reservoir and rivers. Meanwhile, another important reasonis the key technology of breeding and reproduction of rainbow trout is not developedsubstantially. Eyed eggs of rainbow trout are tough with external stimuli, allowinglong-way transportation, thus, convenient for introducing to other regions. Reinforcingthe study of breeding and reproduction technology would benefit the development ofsalmon trout industry.1. The artificial breeding of golden trout.Selection of parent fish, aquaculture management, dry method of artificialfertilization, daily management during hatching and the transportation of eyed eggswere studied in this paper. The temperature, pH and dissolved oxygen were monitoreddaily, so was the light intensity during parent fish rearing. The water temperature rangewas8～12℃during breeding season, pH at8.6～8.8, and dissolved oxygen at9.8～ 10.8mg/L. Biological index of parent fish was measured and gonads was checked usinghistological method. Rate of fertilization and hatching were calculated. The process offry breeding was optimized,including daily feeding, water quality control and diseaseprevention. The beginning of ingestion was the sensitive period of larvae developing,frequently with high death rate.2. Observation of embryonic development and larvae of golden troutCharacteristics of every embryonic phases was described, and fertilized eggs wentthrough cleavage stage, cleavage stage, cleavage stage, cleavage stage and hatchingstage. The embryonic development of golden trout was closely related to the watertemperature, costing19days to reach eyed stage and34days to hatch, and the wholeprocess reached324.36℃.d. The growth of golden trout larvae was recorded and thenew larvae body length was (14.4±0.6) mm, with a vitellicle near belly. The larvaefloated after30days after artificial fertilization, later began to intake bait, a symbol ofbecoming juvenile fish.3. Inducing triploid rainbow trout by heat shockExperiment of inducing triploid rainbow trout by heat shock was conducted, withthree treatment temperatures, namely26℃，28℃，30℃. The treatment processing timewas15min after fertilization and treatment processing duration was15min.The resultshows that using the three temperatures treatment all induced rainbow trout triploidsuccessfully. And from26℃to30℃,the higher temperature, the higher relativepercentage of triploidy embryos, the percentage of triploidy embryos peaked at83.3%with30℃treatment,with higher2h death rate in the meantime. The28℃treatmentgroup had the highest absolute percentage of triploidy embryos at69.3%, signifying themost effective use rato of fertilized eggs and more comprehensive benefits forproduction practice.