Swimming behavior of cultivated juvenile pacific bluefin tuna (Thunnus orientalis) after release from a net cage to the ocean
2007
Endo, C.(Kinki Univ., Nara (Japan)) | Mitsunaga, Y. | Mukai, Y. | Sakamoto, W.
We measured the horizontal and vertical movements of four cultivated juvenile Pacific bluefin tuna after release from a net cage to the ocean. Fish movements were recorded by an ultrasonic telemetry system in Keten bay Amami Island. Using this system, we can monitor simultaneously several tagged individuals. Tagged tuna returned to near the net cage inside Keten bay in the same time. All tagged tuna moved the same direction in Keten bay. The mean swimming speed of tuna was calculated 1.0 FL / sec, and they showed vertical movement during tracking by the boat. Cultivated juvenile bluefin tuna spent about ninety percents of their time in the shallower than twenty-three meters depth which was depth of the net cage. Influence of cultivating in a net cage appeared just after release, but it was not recognized in the next day after release.
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