Consideration on northward transport of juvenile chum salmon in the Sea of Japan off Hokkaido based on particle-tracking experiments (Short paper)
2018
Koyama, T. (Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, Eniwa, Hokkaido (Japan)) | Shinada, A. | Kuroda, H. | Miyakoshi, Y.
Using particle-tracking experiments, based on a high-resolution ocean model, we examined the northward transport of juvenile chum salmon (Oncorhynchus keta), released into the Sea of Japan, by assuming that the particles represented juvenile chum salmon, which were transported passively by ocean currents. The experiments were undertaken for the two brood year classes of juvenile chum salmon; the 2009 brood year class released in the spring of 2010, which showed the lowest return rate among the 2007 to 2010 brood year classes, and the 2007 brood year class released in the spring of 2008, which showed the highest return rate. A remarkable difference in the distribution of the particles was observed between the two brood year classes; i.e., for the 2009 class, particles were transported across a wider range in offshore waters, and the timing at which particles were transported into the Okhotsk Sea through the Soya Strait was delayed. Moreover, the ambient sea water temperature experienced by the particles was lower for the 2009 year class. These results indicated that the post-release transport of juvenile chum salmon by ocean currents was remarkably different between the two years and it may contribute to the low return rate of the 2009 class on the Sea of Japan side of Hokkaido.
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