- 著者一覧
- Takahashi Hiroshi
Takahashi Hiroshi
Id (<span class="translation_missing" title="translation missing: en.view.desc">Desc</span>)
Journal of National Fisheries University Volume 71 Issue 4
pp. 141 - 151
published_at 2023-03
Growth of immature Lates japonicus in eelgrass (Zostera japonica) beds of the Tomouchi River located at around 4.3 km upstream from the river mouth of the Gokase River, Kyushu Island, Japan was studied by the mark and recapture method and scale reading from September 1998 to March 2004. Newly occurring 0-year-old L. japonicus specimens of 13.9–78.0 mm SL (standard length) in Z. japonica beds of the Tomouchi River in August or September reached sizes ranging 58.8–125.7 mm SL by April and 203.4–232.8 mm SL between October and November of the following year. Monthly changes in specific growth rates of individuals demonstrated that rapid growth months of immature fish were limited to the period of high water temperature (22–28℃) from June to October. Also, it was supposed that the large-sized fish of the 0-year-old fish migrated away from Z. japonica beds after December, however a few fish remained in Z. japonica beds until the following November.
Creators :
Takeshita Naohiko
Kondou Takuya
Nagata Shingo
Takahashi Hiroshi
Publishers : National Fisheries University
Journal of National Fisheries University Volume 71 Issue 3
pp. 73 - 80
published_at 2023-03
Viral edema of carp (VEC) caused by the carp edema virus (CEV) causes economic losses for Japanese koi farms. In this study, we investigated the infectivity and pathogenicity of a domestic CEV isolate (genogroup IIa) in koi carp, common carp and goldfish. The challenge test consisted of 9 groups (n = 15):3 groups each of koi carp, common carp, and goldfish, at 15, 20 and 25℃. These groups were challenged with CEV (3.0×10^3 copies/µL) in duplicate. All koi carp died in the 15 and 20℃ groups, but all survived in the 25℃ group. The surviving koi carp in 25℃ groups showed high PCR positive rates of 66.7 and 73.3%, with VEC histopathological changes observed. For the common carp, 1 and 2 fish died in the 20℃ groups, but no deaths or VEC symptoms were observed in the 15 and 25℃ groups. In all common carp groups, PCR-positive fish were observed along with histopathological changes. For all goldfish groups, no deaths or VEC symptoms were observed. As with the common carp, PCR-positive fish were found in all goldfish groups, yet no VEC histopathological changes were detected. These results demonstrate infectivity of this CEV strain in koi carp, common carp, and goldfish, but low pathogenicity in common carp and goldfish.
Creators :
Matsumoto Akane
Honda Kotaro
Takahashi Hiroshi
Kondo Masakazu
Yasumoto Shinya
Publishers : National Fisheries University
Journal of National Fisheries University Volume 70 Issue 1
pp. 27 - 34
published_at 2021-10
The Japanese lates, Lates japonicus is an endemic fish to the Pacific coast of southern Japan, and commonly found in estuaries and coastal waters of Miyazaki and Kochi Prefectures. The larvae, juveniles and young fish stay in the eelgrass, Zostera japonica beds in brackish water areas. Effects of water temperature and salinity on feeding and growth of immature L. japonicus were studied using combinations of seven levels of temperatures (16 to 28℃) and 6 different salinities (9 to 34 ppt) over two experimental periods each of 30 days. At each of these conditions, ten fish were reared in aquaria for periods of 30 days. Based on values of the daily feeding rates, specific growth rates and feeding efficiencies, we found that immature L. japonicus were euryhaline and at salinities ranged from 9 to 34 ppt showed similar feeding and growth rates. The suitable water temperature range was 22 to 28℃, and the optimal water temperature range was 26 to 28℃ for feeding and growth for immature L. japonicus.
Creators :
Takeshita Naohiko
Kondou Takuya
Ikeda Itaru
Takahashi Hiroshi
Nagata Shingo
Hoshino Kazuo
Publishers : National Fisheries University
Journal of National Fisheries University Volume 64 Issue 4
pp. 241 - 247
published_at 2016-03
Creators :
Tanoue Hideaki
Fujiwara Kyoji
Nakahara Takashi
Ogawa Masahiro
Hata Kazuhiro
Enoshima Taketomo
Gotou Hiroshi
Kokatsu Masaki
Ito Takafumi
Takahashi Hiroshi
Komatsu Teruhisa
Mohori Masahiko
Publishers : National Fisheries University
水産大学校研究報告 Volume 54 Issue 4
pp. 143 - 152
published_at 2006-03