Occurrence and body size changes of drifting land-locked Ryukyu-ayu Plecoglossus altivelis ryukyuensis larvae in the San-numata River, Okinawa-jima Island, Japan |
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Authors: | Tatsuya Kawakami Katsunori Tachihara |
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Institution: | (1) Department of Marine Sciences, Faculty of Science, University of the Ryukyus, 1 Senbaru, Okinawa 903-0213, Japan;(2) Present address: Department of Marine Bioscience, Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan |
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Abstract: | The occurrence and body size of drifting land-locked Ryukyu-ayu, Plecoglossus altivelis ryukyuensis, larvae were investigated in the San-numata River, Okinawa-jima Island from November 2000 to March 2001. The water temperature
in the river fluctuated from 13.8 to 17.9°C during the sampling period. The drifting larvae occurred from mid-December to
mid-March with an estimated spawning peak during late November and early December. The notochord length of the drifting larvae
ranged from 4.9 to 6.7 mm (5.7 ± 0.3 mm, mean ± SD), and became longer as the spawning months progressed. These results imply
that the land-locked population possesses the same maturation attributes as the original amphidromous population. |
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Keywords: | |
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