| Budget Amount *help |
¥17,030,000 (Direct Cost: ¥13,100,000、Indirect Cost: ¥3,930,000)
Fiscal Year 2021: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2020: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2019: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2018: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
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| Outline of Final Research Achievements |
Carbon and oxygen otolith stable isotope ratios were measured for Japanese eels that were captured in Japanese rivers. Those eels were classified into naturally-recruited/farmed-and-stocked individuals based on a discrimination model we developed. Along with the previously reported data, we obtained ratios of naturally-recruited/farmed-and-stocked individuals for 21 water systems in 17 prefectures (876 individuals). Ratio of farmed-and-stocked individual were from 41.4% in total with a range from 0.0 to 100.0%. Farmed-and-stocked individuals were dominant in Japan Sea coast where few glass eels recruit. The ratio of farmed-and-stocked individuals tended to be greater in waters that have dams in their lower reaches, even though the water systems are flowing into the Pacific Ocean or the Seto Inland Sea.
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