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SUZUKI Ippei

Field Science Center for Northern Biosphere　Aquatic Research Station　Akkeshi Marine StationSpecially Appointed Assistant Professor

Researcher basic information

■ Degree
  • 博士（環境学）, 東京大学
■ URL
researchmap URL■ Research Keywords and Fields
Research Field
  • Life Science, Ecology and environment

Research activity information

■ Papers
  • Warm season escape to deep: habitat range and seasonal movement of sand tiger shark Carcharias taurus in Ogasawara Archipelago, Japan
    Akane Nagahara; Yanhui Zhu; Masayuki Nakamura; Lisa A. Hoopes; Kazuhiro Nakaya; Ippei Suzuki; Nobuhiko Sato; Mitsuki Kuroda; Yuta Sakuragi; Kenji Minami; Kazushi Miyashita
    Endangered Species Research, 20 Nov. 2025
    English, Scientific journal,
    Temperature-dependent seasonal migrations are well-known in the sand tiger shark
    Carcharias taurus
    in Australia and the USA; however, its behavioral ecology in Japan remains unclear due to limited data. To investigate its habitat use and seasonal movements, we conducted acoustic tracking (n = 5) and archival tagging (n = 3) of individuals around the Chichijima Islands in the Ogasawara Archipelago, Japan. Three acoustic receivers deployed in different coastal areas recorded over 120 d of detections for all sharks, with 3 individuals exceeding 260 d. Average (±SD) acoustic detections were significantly higher in the cool season (275 ± 260) than in the warm season (54 ± 143). Additionally, archival tag data showed that sharks occupied deeper waters during the warm season (78 ± 42 m) than the cool season (24 ± 19 m). The combination of continuous acoustic detections in the cool season and the deepest dives of up to 206 m during the warm season indicates year-round residency of sand tiger sharks in the Ogasawara Archipelago, which is characterized by a continental shelf ranging from 30 to 200 m in depth. Unlike populations in other regions that migrate horizontally over more than 1000 km to maintain suitable temperatures, the Ogasawara population adjusts vertically, exploiting temperature stratification in the water column without extensive horizontal movement. Furthermore, repeated surfacing behaviors from depths greater than 100 m were observed. This study reveals an alternative migratory strategy adapted to the insular and oceanic conditions of the Ogasawara Archipelago.
  • Allometric studies on human- and pig-sized Delphinidae to understand resting metabolic rates with respiratory measurements
    Ippei Suzuki; Yasuaki Niizuma; Daiki Inamori; Yurie Watanabe; Katsufumi Sato; Kagari Aoki
    28 Jan. 2025
  • The effect of a harmful algal bloom (Karenia selliformis) on the benthic invertebrate community and the sea otter (Enhydra lutris) diet in eastern Hokkaido
    Jackson Johnstone; Ippei Suzuki; Randall William Davis; Natsuki Konno; Kyohei Murayama; Satsuki Ochiai; Yoko Mitani
    PLOS ONE, 19, 11, e0303126, e0303126, Public Library of Science (PLoS), 21 Nov. 2024, [Peer-reviewed]
    English, Scientific journal, In recent decades, the locally extinct sea otter (Enhydra lutris lutris) has been recolonizing the coast of eastern Hokkaido. Their diet includes benthic invertebrates such as bivalves, sea urchins, snails, and chitons. In the fall of 2021, a harmful algal bloom (HAB) of Karenia selliformis occurred across Hokkaido’s northern and eastern coasts, leading to a massive mortality of sea urchins. This dinoflagellate produces a neurotoxin (gymnodimine) implicated in shellfish poisoning. To determine the effect of the HAB on the marine community, we conducted benthic surveys using SCUBA and visually monitored the prey items of the sea otters in the affected area from 2020 to 2023. Following the HAB, we observed an 82% decrease in benthic sea urchin density (number m2), leading to their complete absence from the diet of sea otters. Conversely, bivalve density increased six-fold, accompanied by a nearly two-fold rise in their percentage in the sea otters’ diet. Minimal changes were observed in the density of chitons and snails, with no significant alteration in the sea otters’ diet. Despite these changes, the impact of the HAB on otters’ dietary preferences was temporary, as the percentage of dietary sea urchins began recovering one year later. Sea otters augmented their diet with bivalves to compensate for the reduced availability of sea urchins during the HAB with no apparent effects on the number of sea otters or their health. Our results highlight the adaptability of sea otters to adjust their diet according to prey availability.
  • The New Era of Physio-Logging and Their Grand Challenges
    Andreas Fahlman; Kagari Aoki; Gemma Bale; Jeroen Brijs; Ki H. Chon; Colin K. Drummond; Martin Føre; Xavier Manteca; Birgitte I. McDonald; J. Chris McKnight; Kentaro Q. Sakamoto; Ippei Suzuki; M. Jordana Rivero; Yan Ropert-Coudert; Danuta M. Wisniewska
    Frontiers in Physiology, 12, 669158, 669158, Frontiers Media SA, 30 Mar. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Estimation of the feeding record of pregnant Antarctic minke whales (Balaenoptera bonaerensis) using carbon and nitrogen stable isotope analysis of baleen plates
    Mayuka Uchida; Ippei Suzuki; Keizo Ito; Mayumi Ishizuka; Yoshinori Ikenaka; Shouta M. M. Nakayama; Tsutomu Tamura; Kenji Konishi; Takeharu Bando; Yoko Mitani
    Polar Biology, 44, 3, 621, 629, 22 Mar. 2021, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Estimation of Sexual Maturity Based on Morphometrics of Genital Organs in Male Northern Fur Seals, Callorhinus ursinus
    Yukino Hirakawa; Takanori Horimoto; Ippei Suzuki; Yoko Mitani
    Mammal Study, 46, 1, 41, 51, 21 Dec. 2020, [Peer-reviewed]
    English, Scientific journal
  • Feeding ecology of resettling sea otters along the coastal area of eastern Hokkaido
    MITANI Yoko, KITANO Yudai and SUZUKI Ippei
    Annual Report of Pro Natura Foundation Japan, 28, 116, 122, 10 Jan. 2020, [Last author]
  • Development of an animal-borne blood sample collection device and its deployment for the determination of cardiovascular and stress hormones in phocid seals
    Yoshio Takei; Ippei Suzuki; Marty K. S. Wong; Ryan Milne; Simon Moss; Katsufumi Sato; Ailsa Hall
    American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 311, 4, R788, R796, 01 Oct. 2016, [Peer-reviewed]
    English, Scientific journal
  • Drag, but not buoyancy, affects swim speed in captive Steller sea lions
    Ippei Suzuki; Katsufumi Sato; Andreas Fahlman; Yasuhiko Naito; Nobuyuki Miyazaki; Andrew W. Trites
    Biology Open, 3, 5, 379, 386, 15 May 2014, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Validation of a device for accurate timing of feeding events in marine animals
    Ippei Suzuki; Yasuhiko Naito; Lars P. Folkow; Nobuyuki Miyazaki; Arnoldus S. Blix
    Polar Biology, 32, 4, 667, 671, Apr. 2009, [Peer-reviewed], [Lead author]
    English, Scientific journal
■ Other Activities and Achievements
■ Books and other publications
■ Syllabus
  • 大学院共通授業科目（一般科目）：自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 大学院共通授業科目（一般科目）：自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育
■ Research Themes
  • Development of methodology for environmental assessment using energy budget of marine top predators
    Grants-in-Aid for Scientific Research
    01 Apr. 2017 - 31 Mar. 2021
    Sato Katsufumi
    Bio-logging and other methods were applied for marine megafauna including mammals, birds, reptiles and fishes. Each animal adopts own strategy to minimize energy cost and maximize energy gain. For example, mammals and birds, which have high resting metabolic rates, contrived to save energy costs for transit and foraging. On the other hand, active overwintering behavior of juvenile loggerhead turtles in the western North Pacific was driven by a high resting metabolic rate with low thermal dependence. The large body size of whale sharks, the largest extant fish, aids in preventing a decrease in body temperature during deep excursions to more than 1000 m depths without high metabolic costs of producing heat. We have established a new method to understand energy budget in top predators living in ocean ecosystem,
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), The University of Tokyo, 17H00776
  • An animal-borne blood sampler to understand endocrinal mechanism of dive response in submerged phocid seals
    Grants-in-Aid for Scientific Research
    01 Apr. 2015 - 31 Mar. 2018
    SUZUKI Ippei; TAKEI Yoshio; Ailsa Hall; SATO Katsufumi; Marty KS Wong; Simon Moss; Ryan Milne
    This research aimed to understand the endocrinal mechanism of dive response in submerged phocid seals using a newly developed animal-borne blood sampling device. Pool experiments were conducted using captive seals at the Sea Mammal Research Units (Scotland). Blood samples were obtained during conditions when animals were both on land and underwater. Effects of buoyant support and underwater feeding on cardiovascular hormones were compared between the conditions on land and in water, and the conditions with and without feeding, respectively. The response to buoyant support showed similar hormonal changes to decrease blood pressure as same as terrestrial mammals, but the degree of the changes was less. However, feeding in the water did not affect hormone secretions to change blood pressure unlike terrestrial mammals, which suggested phocid seals delayed the digestion to save oxygen in the water. These were the first findings to show quantitative hormonal data from free-swimming animals.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, 15K14567