| Project/Area Number |
14360115
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Hokkaido Tokai University |
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Principal Investigator |
KAERIYAMA Masahide Hokkaido Tokai University, School of Engineering, Hokkaido Tokai University Professor, 工学部, 教授 (80305937)
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| Co-Investigator(Kenkyū-buntansha) |
WADA Eitaro Hokkaido Tokai University, Research Institute for Humanity and Nature, Orifessir, 教授 (40013578)
SUGIMOTO Atsuko Kyoto University, Center for Ecological Research, Professor, 生態学研究センター, 助教授 (50235892)
UEDA Hiroshi Hokkaido University, Field Science Center for Northern Biosphere, Professor, 北方生物圈フィールド科学センター, 教授 (00160177)
TAKADA Takenori Hokkaido Tokai University, School of International Culture, Professor, 国際文化部, 教授 (80206755)
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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 |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2004: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2003: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2002: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Carrying capacity / Oncorhynchus spp. / Density-dependent effect / Sustainable conservation / Ecosystem / Cycle of material / Biodiversity / Climate change / 固体群密度効果 |
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| Research Abstract |
The change in biomass of Pacific salmon (Oncorhynchus spp.) indicates a 30- or 40-year periodicity in the North Pacific Ocean coinciding with long-term climate conditions. We estimated the carrying capacity (K) of sockeye, chum, and pink salmon in the North Pacific Ocean using the replacement level of the Ricker's recruitment t curve, and defined residual carrying capacity (RCC): RCC=(Carrying capacity-Biomass)/(Carrying capacity)x100.A significant positive correlation between Aleutian low pressure index (ALPI) and the carrying capacity was observed at the species level. Factors affecting carrying capacity at the population level, such as reproductive regimes (e.g. survival rate and sea surface temperature (SST) in the early marine life period and hatchery technology), differed by population in Hokkaido chum salmon. The RCC was significantly positively correlated with body size and negatively related to age at maturity in Hokkaido chum salmon populations. The biomass of chum salmon wil
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d populations in the 1990s decreased 50% below that of the 1930s, despite the significant increases in the biomass of hatchery populations. Biological interaction between wild and hatchery populations should be an important consideration in the sustainable management of Pacific Salmon production based at the ecosystem level.
The effects of climate events on the feeding ecology and trophic dynamics of Pacific salmon in offshore waters of the central Gulf of Alaska were investigated during early summers (1994-2000), based on analyses of stomach contents, and carbon and nitrogen stable isotopes. Gonatid squids (mainly Berryteuthis anonychus) were the dominant prey of all salmon species except for chum salmon. During 1997 El Nino event and the 1999 La Nina event, squids decreased sharply in the diets of all Pacific salmon except choho salmon in the Subarctic Current, and chum salmon diets changed from gelatinous zooplankton to a more diverse array of zooplankton species. Aδ13C and δ15N analysis indicated that all salmon species occupied the same branch of the food web in 1999-2000. We hypothesize that high-seas salmon adapt to climate-induced changes in their prey resources bye switching their diets either within or between trophic levels.
The consequences of nutrient loss (oligotrophication) and attendant low productivity on biodiversity and productivity in the ecosystem have recently invoked the interest of researchers, as result of loss of wild anadromous fish (Pacific salmon) by acceleration of urbanization and deterioration of natural riparian ecosystem such dam construction, habitat destruction, and artificial hatchery program. In Japan, chum salmon have been mass-produced by hatchery program, while numerous wild Pacific salmon have been almost extinguished by a combination of the urbanization and the deterioration of riparian ecosystem. Anadromous fish are key species for sustaining production and biodiversity in the riparian ecosystem. For sustainable conservation management of riparian ecosystem, the rehabilitations of wild salmon population, system of material cycle, and natural rivers are critical important issued in Japan. Less
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