| Project/Area Number |
05660213
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Nagasaki University |
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Principal Investigator |
SHIRAKIHARA Kunio Nagasaki Univ., Faculty of Fisheries, Associate Professor, 水産学部, 助教授 (90196618)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEMURA Akira Nagasaki Univ., Faculty of Fisheries, Professor, 水産学部, 教授 (70039725)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | 小型歯鯨スナメリ / 体長推定 / 群れ構造 / 長崎沿岸海域 / 分布 / 生息数 / 生活史 / 系群識別 / ビデオ画像の処理 / 生態学的特性値 |
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| Research Abstract |
This project aimed to estimate the ecological parameters of the finless porpoise (Neophocaena phocaenoides) populations in the coastal waters near Nagasaki by analysing photos taken from an airplane, examining specimens, and sighting surveys from the plane and boats.
A total of photos for 46 individuals were taken. Estimates of body length ranged from 0.7 to 2.2m. Using these photos, the population size in Ariake Sound and Tachiban Bay was estimated to be more than 800 individuals. From airo sighting surveys, another estimate for this population was 3093 individuals.
A paper was published on distribution and seasonal density evaluated from the boat sighting surveys. In the coastal waters near Nagasaki, the species is distributed mainly in Ariake Sound, Tachibana Bay and Omura Bay. Density was estimated 1.31-1.60 individuals/km^2 in the middle part of Ariake Sound. The mean school size was 1.7 individuals
A paper was publised on age, growth and reproduction. The species is born at length of 80 cm and grows up to 140 cm at age of 5 years old. Females attain sexual maturity at ages of 6-9 years. Parturition near Nagasaki is from autumn spring.
Two papers were published on morphology of skeltons. One describes development with age and sexual dimorphism. The other attempted to identify stocks based on geographical difference in the skull morphology. This species attains cranial maturity by 4 years. Sexual dimorphism was not detectable in most of cranial characters. We suggested two stocks exist in the coastal waters near Nakasaki, that is, Ariake Sound-Tachibana Bay stock and Omura Bay stock.
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