| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
The growth history and recruitment of Conger myriaster were studied, based on growth increments in sagittal otoliths of leptocephali collected from Nobeoka (Miyazaki Pref.), Yatsushiro (Kumamoto Pref.), Aji (Kagawa Pref.), Shimizu (Shizuoka Pref.) and Soma (Fukushima Pref.) in 1996 and in 1998. The deep check was recognized at before metamorphic zone from all specimen. The check was called the "Coastal front mark" in the present study and this mark may be useful as a bench mark in studying the growth history and recruitment mechanism of the species. Examination of otoliths showed that larvae has entered into coastal water at the age of 119.5 days, and metamorphosis occurred at 110-210 days. Hatching dates extended from September to January.
Mitochondrial DNA sequences that include a part of the cytochrome b gene to the first half of the control region of 16 C.myriaster leptocephali were determined to evaluate the population structure of the species. A total of 591 nucleotide site, including cytochrome b gene to the first half of the control region, was sequenced from 16 specimens from Nobeoka (Miyazaki Pref.), Yatsushiro (Kumamoto Pref.) and Soma (Fukushima Pref.). Out of 396 nucleotide sites on the control region, 31 (7.8 %) variable, 16 haplotypes being found. Differences between nucleotide sequences ranged between 0.25 and 4.55% with average of 1.88 %, indicating that the control region of the mitochondrial DNA in the species is characterized be high variability. The phylogenetic tree constructed by the neighbor-joining method shows neither significant geographic clusters. This result indicate that the present specimen might come from a single population.
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