Biology and effects of cartilaginous fishes on fisheries in the Sagami Bay
| Project/Area Number | 14560163 |
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Nihon University |
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Principal Investigator |
TANIUCHI Toru Nihon University, College of Bioresource Sciences, Professor, 生物資源科学部, 教授 (00012021)
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| Co-Investigator(Kenkyū-buntansha) |
KOJIMA Takahito Nihon University, College of Bioresource Sciences, Associate Professor, 生物資源科学部, 助教授 (60205383)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed(Fiscal Year 2004)
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| Budget Amount *help |
¥4,000,000 (Direct Cost : ¥4,000,000)
Fiscal Year 2004 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 2003 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 2002 : ¥1,300,000 (Direct Cost : ¥1,300,000)
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| Keywords | Sagami Bay / cartilaginous fishes / distribution / Reproduction / age character / growth / food habits / predation / サメ類 / 年齢 / 定同位対比 / 食地位 / 寄生性カイアシ類 / 単生類 / 軟骨魚類 / 棘断面 / 年齢査定 / 安定同位対比 / 寄生虫 / 分布構造 / 年齢と成長 |
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| Research Abstract |
The total number of 21 species of cartilaginous fishes were collected from the depth below 150 m in the Sagami Bay during the course of the present study. Three triakid species were provided by fishermen. Among those species, most abundant species was Squalus mitsukurii, making up 69% of the total catch of 442 specimens captured by R/V Enoshima-maru belonging to Kanagawa Prefectural Fisheries Research Center. Other species constituted less than 10 % of the total.
Shortspined dog fish, S.mitsukurii, ranged from 150 m to 550 m in depth, mainly between 300-400 m. Trend of catch per unit efforts (CUPUE) using hooked rates expressed by number caught per hundred hooks and unit net length, indicates that they made seasonally vertical migration and go into deep waters during warm seasons while they inhabit shallower depth during cold seasons. However, they were not caught in mid-winter in the coastal waters while they are captured in the seamount near the entrance of Tokyo Bay., suggesting hori
… More
zontal migration within the bay as well. Segregation by sizes and sexes were also suggested, judging from scarcity of males and small specimens in the catch. Predation by S.mitsukurii on commercially important fishes distributed in the Sagami Bay was also investigated using stomach contents analysis and tooth scars of damaged fishes. As a result, it is concluded that about 8 % of fishes caught by vertical loglines suffered from predation by S.mitsukurii. Age and growth studies were also conducted using annuli marked on second dorsal fin spines. Growth curves were close to those presented by the past studies in offshore area of Choshi while quire different from those in Ogasawara and Seamount of Hancock... Reproductive studies of S.mitsukurii indicate that reproductive strategy is a little different from that obtained from Choshi area. Stomach contents analysis reveals that there seemed to be a little different between regions in Sagami Bay but totally S.mitsukurii are an exclusive picivore as reported by other studies in other regions. Feeding status of seven species was analyzed using stable isotope ratio of nitrogen and carbon. C-N maps indicated that differences between species are rather smaller than differences between habitats. They also differed according to growth stage. Less
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Report
(4results)
Research Products
(21results)
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[Book] 水の事典2004
Author(s)
谷内 透 他
Total Pages
551
Publisher
朝倉書店
Description
「研究成果報告書概要(和文)」より
Related Report
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