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Where Do Juvenile Pacific Bluefin Tuna Travel? Japan, February 28, 13

Japanese scientists are closing in on the migration route of juvenile Pacific bluefin tuna (PBT), which is important for improving accuracy in assessing and managing the PBT stock.
Recent studies from Japan’s National Research Institute of Far Seas Fisheries suggest the juvenile PBT migrate northward with the Kuroshio Current from their spawning ground near the Nansei Islands, which are located between Taiwan and Japan. The research indicates the PBT juveniles probably pass through off the west coast of Yakushima Island before separating into two migrating groups; some of the tuna move up along Japan’s west coast into the Sea of Japan, while others migrate northeast to Japan’s Pacific side.
By identifying their migration route, the scientists are hoping to evaluate the juvenile abundance before the baby tuna are caught in the pole-and-line fishery near Tosa Bay and Goto Islands in southern Japan. Monitoring juvenile abundance is essential for providing early estimates of annual catch levels, which in turn can provide a timely and accurate stock assessment for better stock management.
The Japanese scientists are interested in developing ways to successfully monitor juvenile PBT abundance, particularly around Yakushima Island before the tuna separate. They are also looking to analyze the marine environments to determine what oceanographic factors cause the two different tuna migration patterns.