2000 Fiscal Year Final Research Report Summary
Development of monitoring systems for studying ecology and behavior of bottlenose dolphins-taking aerial pictures of schools using a captive balloon system and recording underwater vocalizations using a sonobuoy system-
| Project/Area Number |
10460086
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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 | Mie University |
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Principal Investigator |
SHIRAKIHARA Kunio Mie University, Faculty of Bioresources Professor, 生物資源学部, 教授 (90196618)
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| Co-Investigator(Kenkyū-buntansha) |
HURUSAWA Masahiko Tokyo University of Fisheries, Faculty of Fisheries, Professor, 水産学部, 教授 (60281002)
ISHIMATSU Takakazu Nagasaki University, Faculty of Engineering Professor, 工学部, 教授 (10117062)
KASUYA Toshio Mie University, Faculty of Bioresources Professor, 生物資源学部, 教授 (00013574)
AKAMATSU Tomonari National Research Institute of Fisheries Engineering, Researcher, 漁業生産工学部, 農林水産技官(研究職)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Bottlenose dolphin / Amakusa / Balloon system / Aerial picture / Sonobuoy / Under-water vocalization / Theodolite tracking / Photo-identification |
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| Research Abstract |
Indo-Pacific bottlenose dolphins are found thoughout a year in the coastal waters of Amakusa, Kyushu, Japan. To study ecology and behavior of the dolphins, monitoring systems have been developed ; a captive balloon system for taking aerial pictures of schools and a sonobuoy system for recording underwater vocalizations from schools.
The balloon system consists of a captive balloon(2.5 m in diameter)filled with the helium gas, a video sub-system(2.1 kg)suspended from the balloon and a control sub-system on a boat. The following information was obtained from images of a schoo1 ; aerial behavior of the school members, temporal changes in number of surfacing individuals, configuration of the school and spatial distribution of individuals. Mother-calf pairs were distinguishable from others when a small portion of the school was taken using a telephoto lens. Seasonal changes in ratios of mothercalf pairs to all the individuals suggest the main parturition season of spring to autumn. This system is applicable to outer cetaceans.
Tother with surveys using the two systems, direct recordings of vocalizations by a hydrophon from a boat, theodolite tracking from land, behavior observations, and photographic surveys for individual identification were attempted. Vocalization recordings show that the dolphins searched sometimes a few meters ahead or 200 m ahead. Theodolite tracking surveys clarify a regular movement pattrn along the shore in the daytime. Behavior observations suggest that the dolphins take a rest in a limited areas during the heat of the day. Individual identification surveys give estimetes of population size of almost 200 individuals and mortality rate of 3.4% per year.
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