| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2015: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2014: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Outline of Final Research Achievements |
Our analysis of the oceanic migratory behavior of large female Anguilla japonica silver eels with pop-up satellite archival tags found that they first use the Kuroshio Current and then go south into the open sea near the Ogasawara Islands. The daily rhythm of diel vertical migration of Japanese eels observed in the open sea and their spawning area was the same behavior found in all areas during their spawning migration. A clear relationship between the upper and lower limits of migration and the sun and moon light and water temperature was found. Their experienced temperatures estimated from the development rate of collected eggs was not significantly different from the environmental temperature from CTD data, only if spawning occurred at 1:00 at night 3 days before new moon in all cases. Therefore, we hypothesize that Japanese eels spawn at about 1:00 a.m. and internal tide patterns may contribute to the mechanisms that determine the places they spawn in the open ocean.
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