TOKYOMay 25 (News On Japan) – A research group from Tokyo University of Marine Science and Technology has successfully produced king salmon using rainbow trout, which can spawn multiple times, unlike king salmon that die after one spawning.
This achievement is of great importance both for the efficiency of aquaculture and for the conservation of the King Salmon species, which is in danger of extinction on the west coast of the United States.
King salmon, sockeye salmon and rainbow trout all belong to the genus Oncorhynchus. These salmon species typically hatch in rivers, migrate to the Pacific Ocean for three to four years, and then return to their natal rivers to spawn. After spawning, King Salmon and Sockeye Salmon die shortly afterwards. However, despite being of the same genus, the rainbow trout can reproduce every year without dying after spawning.
Professor Goro Yoshizaki and his team focused on this difference and examined the germ cells responsible for eggs and sperm in these salmon during their spawning period. They discovered that in King Salmon and other salmon that die after spawning, the germ cells disappear completely during the spawning period, while in Rainbow Trout the germ cells persist even after spawning.
By transplanting King Salmon germ cells into Rainbow Trout that had been modified so that they could not produce their own eggs or sperm, the researchers were able to get the Rainbow Trout to produce King Salmon eggs for three years and sperm for four years.
Further experiments breeding these germ cell-transplanted rainbow trout resulted in offspring that hatched at almost the same time as King Salmon and grew into salmon with DNA nearly identical to that of King Salmon.
The results of this study are expected to significantly improve the efficiency of aquaculture for king salmon, a species with high commercial value but which takes a long time to mature and dies after one spawning.
Because King Salmon are threatened with extinction on the west coast of the United States, combining this research with long-term cell preservation techniques could potentially allow the recovery of individual fish from preserved cells.
Professor Yoshizaki said: “This technology is important not only for improving aquaculture efficiency, but also for species conservation. We hope to accelerate the analysis of why King Salmon and similar species die once spawned.”
The research has been published in an open-access journal founded by the publisher of ‘Science’.
Source: ANN
