Nobuto Fukuda
University of Tokyo
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Nobuto Fukuda.
Journal of Fish Biology | 2009
Nobuto Fukuda; Mari Kuroki; Akira Shinoda; Yoshiaki Yamada; Akihiro Okamura; Jun Aoyama; Katsumi Tsukamoto
The influences of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers were investigated using individuals reared at 5, 10, 15, 20, 25 and 30 degrees C and in fed or unfed conditions at salinity 32 after their otoliths were marked with alizarin complexone (ALC). To eliminate the difficulty of observing the edges of otoliths with optical (OM) or scanning electron (SEM) microscopes, three to 10 individuals were sampled from each tank at 10, 20 and 30 days during the experiment and reared for an additional 10 days at 25 degrees C after their otoliths were marked a second time. Otolith growth and the number of increments were measured using both OM and SEM. Most A. japonica commenced feeding after 10 days at 20-30 degrees C or after 20 days at 15 degrees C, but no feeding occurred at 5 and 10 degrees C. No otolith growth occurred at 5 and 10 degrees C except in two individuals with minimal increment deposition at 10 degrees C. Otolith growth was proportional to water temperature within 15-25 degrees C and not different between 25 and 30 degrees C. At 15, 25 and 30 degrees C, the mean otolith growth rate in fed conditions was higher than in unfed conditions. The number of increments per day was significantly different among water temperatures (0.00-0.01 day(-1) at 5 and 10 degrees C, 0.43-0.48 day(-1) at 15 degrees C and 0.94-1.07 day(-1) at 20-30 degrees C). These results indicated that otolith growth in A. japonica glass eels and elvers was affected by temperature and ceased at < or =10 degrees C under experimental conditions. Hence, future studies analysing the otoliths of wild-caught A. japonica glass eels and elvers need to carefully consider the water temperatures potentially experienced by the juveniles in the wild.
Journal of Fish Biology | 2018
Nobuto Fukuda; Hiroaki Kurogi; Daisuke Ambe; S. Chow; Toshihiro Yamamoto; Kazuki Yokouchi; Akira Shinoda; Y. Masuda; Masashi Sekino; K. Saitoh; M. Masujima; Tomowo Watanabe; Noritaka Mochioka; Hiroshi Kuwada
This study clarifies the location, size and age at the onset of metamorphosis in Japanese eels Anguilla japonica through oceanic surveys, rearing experiments and analyses of the morphology and otoliths of leptocephali and glass eels. Twenty-eight metamorphosing leptocephali were collected in the mesoscale eddy region to the east of Taiwan during research expeditions in 2004. Rearing experiments showed that the total length (LT ) of leptocephali decreased by an average of 12·5% during metamorphosis and 13·9% during the 2-12 h after death. Thus, the mean back-calculated LT at the onset of metamorphosis for 630 glass eels from Taiwan and Japan was estimated at 67·8 ± 2·7 mm (mean ± S.D.). The estimated mean ante-mortem size of the fully grown pre-metamorphic leptocephali collected in 2004 was 64·6 ± 3·4 mm, which was consistent with the LT estimate for glass eels. Otolith analysis showed that the mean age at the onset of metamorphosis was 137 ± 15 days and indicated that Japanese eels may have a recruitment route through the mesoscale eddies to the east of Taiwan in addition to the direct transfer route from the North Equatorial Current to the Kuroshio Current.
Biology Letters | 2018
Kazuki Yokouchi; Françoise Daverat; Michael J. Miller; Nobuto Fukuda; Ryusuke Sudo; Katsumi Tsukamoto; Pierre Elie; W. Russell Poole
Many diadromous fishes such as salmon and eels that move between freshwater and the ocean have evolved semelparous reproductive strategies, but both groups display considerable plasticity in characteristics. Factors such as population density and growth, predation risk or reproduction cost have been found to influence timing of maturation. We investigated the relationship between female size at maturity and individual growth trajectories of the long-lived semelparous European eel, Anguilla anguilla. A Bayesian model was applied to 338 individual growth trajectories of maturing migration-stage female silver eels from France, Ireland, the Netherlands and Hungary. The results clearly showed that when growth rates declined, the onset of maturation was triggered, and the eels left their growth habitats and migrated to the spawning area. Therefore, female eels tended to attain larger body size when the growth conditions were good enough to risk spending extra time in their growth habitats. This flexible maturation strategy is likely related to the ability to use diverse habitats with widely ranging growth and survival potentials in the catadromous life-history across its wide species range.
Reviews in Fish Biology and Fisheries | 2011
Akira Shinoda; Jun Aoyama; Michael J. Miller; Tsuguo Otake; Noritaka Mochioka; Shun Watanabe; Yuki Minegishi; Mari Kuroki; Tatsuki Yoshinaga; Kazuki Yokouchi; Nobuto Fukuda; Ryusuke Sudo; Seishi Hagihara; Kei Zenimoto; Yuzuru Suzuki; Machiko Oya; Tadashi Inagaki; Shingo Kimura; Atsushi Fukui; Tae Won Lee; Katsumi Tsukamoto
Estuarine Coastal and Shelf Science | 2012
Kazuki Yokouchi; Nobuto Fukuda; Michael J. Miller; Jun Aoyama; Françoise Daverat; Katsumi Tsukamoto
Environmental Biology of Fishes | 2011
Kazuki Yokouchi; Nobuto Fukuda; Kotaro Shirai; Jun Aoyama; Françoise Daverat; Katsumi Tsukamoto
Fisheries Science | 2013
Nobuto Fukuda; Michael J. Miller; Jun Aoyama; Akira Shinoda; Katsumi Tsukamoto
Coastal marine science | 2010
Mari Kuroki; Nobuto Fukuda; Yoshiaki Yamada; Akihiro Okamura; Katsumi Tsukamoto
Environmental Biology of Fishes | 2016
Nobuto Fukuda; Jun Aoyama; Kazuki Yokouchi; Katsumi Tsukamoto
Environmental Biology of Fishes | 2017
Ryusuke Sudo; Akihiro Okamura; Nobuto Fukuda; Michael J. Miller; Katsumi Tsukamoto