Japanese scientists have enabled sterile salmon to give birth to trout. The team from Tokyo University of Marine Science and Technology and the Japan Science and Technology Agency found that implanting reproductive cells from rainbow trout in sterile salmon embryos resulted in adult salmon that produced trout offspring. Trout and salmon are both part of the salmonid family, which is under threat of extinction, the researchers said. They hope the technique will enable them to breed threatened species when eggs cannot be frozen.