King salmon is very delicious, but it is not cultured in Japan because of the difficulty to breed it. However, YamanashiPrefectural Fishery Technology Center developed a new breed by king salmon and rainbow trout. The new breed is name “Nijinosuke.” With the help of the chromosome manipulation technology used to produce seedless watermelons, the research team increased the number of chromosomes by immersing fertilized eggs of rainbow trout for a given length of time and successfully grew them to be about 60 cm in length and 2 kg in weight in three years.
Experiments started in 2007, and the researchers confirmed in October 2011 that female Nijinosuke does not have the reproduction function, though male Nijinosuke has it. They are currently working on the technology to produce and nurture eggs that brings only female Nijinosuke. If a new breed is culture, it is necessary to verify that it does not have the reproduction function to prevent ecology from being destroyed. Otherwise, it is impossible to get approval from the Ministry of Agriculture,Forestry and Fisheries. Nagano Prefectural Fisheries Experimental Station has already launched “Shinshu Salmon” by rainbow trout and brown trout using the chromosome manipulation technology. Shinshu Salmon is growing popular and sold at a high price on the market.