Japanese salmon bred with 'surrogate' fish

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TOKYO, Jan. 15 (UPI) -- Japanese scientists say they've successfully bred a type of salmon indigenous to the country through the use of surrogate parents of a different species.

Researchers at the Tokyo University of Marine Science and Technology reported they extracted spermatogonia, or primordial germ cells, from endangered yamame salmon, a Japanese species that lives the entirety of its life in rivers.

The germ cells were implanted into sterile rainbow trout hatchlings, where the cells developed into fully functioning sperm or egg cells depending on the trout's gender, The Japan Daily Press reported Tuesday.

The sperm and egg cells can then be brought together using in vitro fertilization in order to produce a healthy yamame salmon, researchers said.

"I would like to make a bank of reproductive cells of the world's endangered fish, and we would store them until rivers became healthy environments again, after which we would raise the fish and release them," researcher Goro Yoshizaki, a professor of marine science, said.

The researchers said they hope to someday apply the same technology on other species, first on amphibians, then to reptiles, and hopefully to mammals as well.

"But the hurdle is still high because the sets of genes are much more different between male and female mammals," Yoshizaki said.