| Budget Amount *help |
¥15,730,000 (Direct Cost: ¥12,100,000、Indirect Cost: ¥3,630,000)
Fiscal Year 2011: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2010: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2009: ¥12,090,000 (Direct Cost: ¥9,300,000、Indirect Cost: ¥2,790,000)
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| Research Abstract |
Migration history including spawning area of Ayu(Plecoglossus altivelis), Biwa trout(Oncorhynchus masou rhodurus), Japanese eel(Anguilla japonica) was studied using otolith stable isotope ratios(^<87> Sr/^<86> Sr,δ^<13> O). Otolith^<87> Sr/^<86> Sr analysis showed that ayu juvenile did not migrate to the hatched river. The analysis also determined that Biwa trout returned to hatched river and spawned, but the returning migration being vague with entering into neighboring rivers of hatched one. Otolith^<87> Sr/^<86> Sr of spawning adult eels collected in the spawning area west of Mariana Trench revealed the growth area of some adult eels to be rivers or estuaries in the Pacific coast of Japan, suggesting that eels in Japan contribute to the reproduction of the species.δ^<13> O of the central portion of glass eel otoliths determined the spawning temperature and depth of the Japanese eel to be 26℃and 150-170 m deep, respectively, which provided important information for collecting eel eggs in spawning area of the Japanese eel in 2009 and 2011 by Hakuho-Maru research cruises.
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