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Study on the Life History of Finless Porpoise Living in the Coastal Waters of Nagasaki.

长崎近海江豚生活史研究。

基本信息

批准号：
01560212
负责人：
TAKEMURA Akira
金额：
$ 0.64万
依托单位：
Nagasaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01560212/
关键词：
Finless Porpoise Distribution Migration Reproduction Growth Maturity 移動生殖

项目摘要

1. ON THE DISTRIBUTION AND MIGRATION(1) OMURA BAYA pattern of the seasonal migration was discussed by some data from sighting surveys. Namely, the finless porpoises aggregate in Southeast area of this bay in Winter and spread over in the whole bay in Summer. But, data were not sufficient to discuss the migration in detail. Moreover, we could not find out any evidence to prove whether they go out from this bay or not.(2) ARIAKE SOUND AND TACHIBANA BAYSighting surveys at every stations of these areas for two years clarified a following pattern of the seasonal migration. They migrate between the inner part of Ariake Sound and Tachibana Bay, and have a tendency to aggregate in the inner part of Ariake Sound in Winter.2. RELATION WITH FISHERIESTheir food was consisted of many kinds of small aquatic animals, namely fish, mollusca, crustacean and etc. The catch of these preys of this porpoise was decreasing in Omura Bay, but this tendency was not clear in Ariake Sound and Tachibana Bay.3. LIFE HISTORYA parturition season of this porpoise estimated from the dates collecting neonates or fetuses was from Autumn to Winter. Then, it seems that the aggregation in Winter is related with breeding. Males (3.5 years old) mature earlier than females (7-8 years old). The oldest individual (female) was 25.5 years old.4. POPULATIONIt was very difficult to decide the accurate number, because the number of porpoises sight was a few. However, we can say that the population in Omura Bay was in a critical situation (its size of several tens to a hundred) and much smaller than the population in Ariake Sound and Tachibana Bay.

1.（1）根据观测资料，讨论了大村湾季节性迁徙的格局。即冬季江豚主要聚集在湾东南部，夏季则向全湾扩散。但是，数据不足以详细讨论迁移。而且，我们也找不到任何证据来证明他们是否从这个海湾出去。(2)在这些地区的每个观测站进行了两年的观测，澄清了以下季节性迁移的模式。它们在有明海峡内部和立花湾之间迁移，冬季有向有明海峡内部聚集的趋势。与渔业的关系以鱼类、软体动物、甲壳类等多种小型水生动物为食物，大村湾的捕获量呈下降趋势，有明湾和立花湾的趋势不明显.生活史根据仔、幼仔的采集日期，推测该江豚的分娩季节为秋季至冬季。由此看来，冬季聚集与繁殖有关。雄性（3.5岁）比雌性（7-8岁）成熟早。年龄最大的个体（女性）为25.5岁。很难确定准确的数量，因为海豚的数量很少。但是，我们可以说，大村湾的人口处于危急状态（几十到一百人的规模），比有明湾和立花湾的人口少得多。