著者

神田 育子 古山 歩 若林 郁夫 若井 嘉人 船坂 徳子 吉岡 基 Kanda Ikuko Furuyama Ayumi Wakabayashi Ikuo Wakai Yoshito Funasaka Noriko Yoshioka Motoi

出版者

三重大学大学院生物資源学研究科

雑誌

三重大学大学院生物資源学研究科紀要 = The bulletin of the Graduate School of Bioresources Mie University

巻号頁・発行日

vol.47, pp.13-23, 2021-12

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In this study, we aimed at clarifying the recent trends in narrow-ridged finless porpoise stranding on the west coast of Ise Bay. We analyzed the annual/monthly change in the number of stranded individuals, the status found, the length and sex of the individuals, and the seasonality of the geographical distribution data from 486 individuals collected along the northern central coast of Mie Prefecture for 10 years from January 2011 to December 2020. The annual number of stranded individuals fluctuated between 2011 and 2015, although it was stably around 60 individuals after 2016 when a local stranding network of universities, aquariums, museums, and local governments were established. As for the status of stranding, 96.5% of the individuals were found alone and they were dead except one. More males were observed among the stranded individuals than females with a sex ratio of 1.4. The body length frequency data showed that 75-85 cm individuals, approximately of birth length, accounted for 51.1% and 39.1% in the male and female groups, respectively, and stranding during the newborn period was overwhelmingly predominant. Several individuals below the birth length were found in April-July while the peak of calving season was considered to be April-June. The monthly number of stranded individuals peaked in May-June every year, and dead newborn calves were major factors in boosting the number of stranded individuals found during this period. The geographical distribution of stranded individuals displayed seasonal changes. Most stranded animals were recorded in the central part of the west coast of Ise Bay in April-June, exhibiting a gradual decrease and becoming scarce by January-March.

著者

Morisaka Tadamichi Sakai Mai Kogi Kazunobu Nakasuji Akane Sakakibara Kasumi Kasanuki Yuria Yoshioka Motoi

出版者

Public Library of Science

雑誌

PloS one (ISSN:19326203)

巻号頁・発行日

vol.8, no.8, 2013-08-28

被引用文献数

4

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野生イルカの突発性射精(夢精)を世界で初めて記録 : さまざまな動物で見られる現象か?. 京都大学プレスリリース. 2013-08-28 Spontaneous ejaculation, which is defined as the release of seminal fluids without apparent sexual stimulation, has been documented in boreoeutherian mammals. Here we report spontaneous ejaculation in a wild Indo-Pacific bottlenose dolphin (Tursiops aduncus), and present a video of this rare behavior. This is the first report of spontaneous ejaculation by an aquatic mammal, and the first video of this behavior in animals to be published in a scientific journal.

著者

新田 恭大 向井 貴彦 淀 太我 吉岡 基 NITTA Yasutomo MUKAI Takahiko YODO Taiga YOSHIOKA Motoi

出版者

三重大学大学院生物資源学研究科

雑誌

三重大学大学院生物資源学研究科紀要

巻号頁・発行日

vol.40, pp.45-64, 2014-03-01

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The fish fauna of the Ano River in Mie Prefecture, central Japan, was surveyed between May 2013 and August 2013. A total of 1242 individuals of 38 species belonging to 15 families were collected from 13 stations and 3 species belonging to 3 families were visually confirmed. Six species, Dasyatis akajei, Opsariichthys uncirostris uncirostris, Microphis(Oostethus)brachyurus brachyurus, Plectorhinchus cinctus, Kuhlia marginata, Rhinogobius sp. BF, Rhinogobiussp. OM were newly added to the fish fauna of the Ano River. Six alien species were collected and seven species of threatened fishes in red list of Ministry of Environment Japan or in red databook of Mie Prefecture, such as Cottus reinii were collected. Two of these alien species, Micropterus salmoides and Lepomis macrochirus macrochirus were designated “Invasive Alien Species” by Invasive Alien Species Act (Law of Japan). Other four species, Acheilognathus rhombeus, Opsariichthys uncirostris uncirostris, Rhinogobius sp. OM, and Tachysurus nudiceps were domestic alien speceies and the former three species were evidently introduced from Lake Biwa basin. It seemed that a dam(1.8m in hight) which constructed in the middle leach of the river disturb diadromous migration. Control of alien species and improvement of the fish way on the dam are necessary to conserve fish biodiversity in the Ano River.

著者

吉岡 基 Yoshioka Motoi

出版者

三重大学生物資源学部

雑誌

三重大学生物資源学部紀要 = The bulletin of the Faculty of Bioresources, Mie University (ISSN:09150471)

巻号頁・発行日

vol.16, pp.45-48, 1996-03-01

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This paper briefly reviews some works on reproductive physiology in cetaceans with special reference to dolphins from the following aspects: estrous cycle in female dolphins, hormonal profiles during pregnancy, testosterone levels and seasonality in testicular activity, ovulation induction and sperm collection and freezing.

著者

Morisaka Tadamichi Sakai Mai Kogi Kazunobu Nakasuji Akane Sakakibara Kasumi Kasanuki Yuria Yoshioka Motoi

出版者

Public Library of Science

雑誌

PloS one (ISSN:19326203)

巻号頁・発行日

vol.8, no.8, 2013-08-28

被引用文献数

4

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野生イルカの突発性射精(夢精)を世界で初めて記録 : さまざまな動物で見られる現象か?. 京都大学プレスリリース. 2013-08-28