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Ono Y, Tsuchida S, Hirasaka K, Myosho T, Fujimoto S, Shimizu K, Yagi M. Environmental DNA Reveals Geographic Distributions of Two eel Species, Anguilla japonica and A. marmorata, in Western Kyushu, Japan. Zoolog Sci 2024; 41:392-399. [PMID: 39093285 DOI: 10.2108/zs230103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 02/22/2024] [Indexed: 08/04/2024]
Abstract
Some anguillid eels migrate thousands of kilometers from their spawning grounds, dispersing across vast geographic areas to fresh and brackish water habitats, where they settle and grow. Japanese eels (Anguilla japonica) and giant mottled eels (A. marmorata) are both found in Japan, although their distributions differ, and their exact distributions are poorly known. We assumed that topographic distribution patterns of Japanese and giant mottled eels must differ among and within rivers along the northwest coast of Kyushu, Japan. Environmental DNA (eDNA) analysis was conducted at 87 sites in 23 rivers. Japanese eel eDNA was detected in 19 rivers (82.6%) and that of giant mottled eels was detected in eight (34.8%). We detected giant mottled eel eDNA in five rivers where they were previously unknown. eDNA for Japanese eels was detected at six of nine sites in the north (66.7%), 13 of 23 sites in Omura (56.5%), and 37 of 55 sites in the south (67.3%). In contrast, giant mottled eel eDNA was detected at one of nine sites in the north (11.1%), no sites in Omura, and 15 of 55 sites in the south (27.3%). There was no correlation between eDNA concentrations of the two species at 10 sites in the five rivers where eDNA of both species was detected. These findings suggest differences in the distribution of the two eel species and the northern distributional limit of giant mottled eels in the area facing the East China Sea.
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Affiliation(s)
- Yurika Ono
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - Shimpei Tsuchida
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - Katsuya Hirasaka
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - Taijun Myosho
- Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Shingo Fujimoto
- Integrated Technology Center, University of the Ryukyus, Okinawa 903-0213, Japan
| | - Kenichi Shimizu
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - Mitsuharu Yagi
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan,
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Maeda T, Hagihara S, Wakiya R, Kimura S. Can displaced Anguilla marmorata return to their original habitat? Daily tracking study of their homing behavior. JOURNAL OF FISH BIOLOGY 2024. [PMID: 38811345 DOI: 10.1111/jfb.15824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/12/2024] [Accepted: 05/15/2024] [Indexed: 05/31/2024]
Abstract
Anguilla marmorata collected in the Odana River lower reaches were passive integrated transponder-tagged displaced and released into the upper river reaches (54 up-transported eels), and eels collected in the upper reaches were tagged and released downstream (52 down-transported eels). Their movements were detected once per day for 10 days using a portable radio-frequency identification (RFID) system. The homing rate of the down-transported eels was 38.9%, compared to 3.7% for the up-transported eels, suggesting that eels inhabiting upstream areas have relatively high fidelity to their habitats and downstream eels have less fidelity.
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Affiliation(s)
- Tatsuhiko Maeda
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Seishi Hagihara
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
- Nanae Freshwater Station, Field Science Center for Northern Biosphere, Hokkaido University, Hokkaido, Japan
| | - Ryoshiro Wakiya
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Shingo Kimura
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
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Kume M, Yoshikawa Y, Tanaka T, Watanabe S, Mitamura H, Yamashita Y. Water temperature and precipitation stimulate small-sized Japanese eels to climb a low-height vertical weir. PLoS One 2022; 17:e0279617. [PMID: 36574439 PMCID: PMC9794052 DOI: 10.1371/journal.pone.0279617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 12/12/2022] [Indexed: 12/28/2022] Open
Abstract
Although river-crossing structures can have a detrimental effect on the movement and distribution of anguillid eels (genus Anguilla), they have inhabited locations upstream of river-crossing structures in many rivers. However, the growth stage in which the eels start to climb river-crossing structures remains unclear. In this study, we directly observed, using infrared video camera systems, that the Japanese eel (Anguilla japonica) climbs a low-height vertical weir as a migratory barrier, confirming the ability of eels to climb over a low-height weir within a river. All eels climbed the weir at night, between sunset and sunrise. We observed that the total length of Japanese eels that climbed the weir ranged from 60 to 140 mm, suggesting that eels inhabiting the upstream area of a weir climbed it when they were small and then lived and grew upstream. Moreover, the general additive model showed considerable effects of water temperature and precipitation on eel climbing, suggesting that water temperature and precipitation are important for its activation. The results of this study also show the effectiveness of infrared video cameras in monitoring eel climbing, which could be applied to monitor fish migratory behavior through fish passages. The findings of this study are useful for the comprehensive management and conservation of wild eel stocks.
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Affiliation(s)
- Manabu Kume
- Field Science Education and Research Center, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto, Japan
| | - Yudai Yoshikawa
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto, Japan
| | | | - Shun Watanabe
- Faculty of Agriculture, Kindai University, Nara, Japan
| | - Hiromichi Mitamura
- Field Science Education and Research Center, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto, Japan
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto, Japan
| | - Yoh Yamashita
- Field Science Education and Research Center, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto, Japan
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Wakiya R, Itakura H, Hirae T, Igari T, Manabe M, Matsuya N, Miyata K, Sakata MK, Minamoto T, Yada T, Kaifu K. Slower growth of farmed eels stocked into rivers with higher wild eel density. JOURNAL OF FISH BIOLOGY 2022; 101:613-627. [PMID: 35678211 DOI: 10.1111/jfb.15131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Farmed anguillid eels are frequently stocked into natural fresh waters to enhance eel resources, but little is known about what happens to these eels or their interactions with wild eels after stocking. A recent study observed a depressed survival and growth rate of farmed Japanese eels when they were reared with wild eels, which indicated that wild eels might interfere with the survival and growth of farmed-and-stocked eels through intraspecific competition. To contribute to improving eel stocking efficiency, the growth of farmed-and-stocked Japanese eels was compared among four rivers with different wild eel densities using mark-and-recapture studies. Based on the 2-year recapture survey after stocking, it was found that the density of the farmed-and-stocked eels was not significantly different among rivers. The daily growth rates of farmed-and-stocked eels in the rivers with lower wild eel density were significantly higher than those of the eels stocked into the rivers with higher wild eel density. The farmed-and-stocked eels moved significantly greater distances downstream than wild eels that showed sedentary behaviour. This and previous studies indicate that significant questions remain about the effectiveness of stocking farmed eels into water bodies where naturally recruited wild eels are present.
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Affiliation(s)
- Ryoshiro Wakiya
- Research and Development Initiative, Chuo University, Tokyo, Japan
| | - Hikaru Itakura
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, Maryland, USA
| | - Tatsumu Hirae
- Fisheries Technology and Development Center, Kagoshima, Japan
| | - Tadamitsu Igari
- Fisheries Technology and Development Center, Kagoshima, Japan
| | - Miyuki Manabe
- Fisheries Technology and Development Center, Kagoshima, Japan
| | - Noriaki Matsuya
- Inland Water Fisheries Institute, Aomori Prefectural Industrial Technology Research Center, Aomori, Japan
| | | | - Masayuki K Sakata
- Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Toshifumi Minamoto
- Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Takashi Yada
- Nikko Field Station, Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Nikko, Japan
| | - Kenzo Kaifu
- Faculty of Law, Chuo University, Hachioji-shi, Japan
- The Zoological Society of London, London, UK
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