On August 8, the Committee on the International Prize for Biology (chaired by Dr. FUJIYOSHI Yoshinori, Distinguished Professor, Tokyo Medical and Dental University) decided to award the 38th (2022) International Prize for Biology to Dr. TSUKAMOTO Katsumi, Professor Emeritus, The University of Tokyo, Japan. This year’s Prize is awarded in the field of the Biology of Fishes.

1980                      Doctor of Agriculture with a major in Fisheries Science, The University of Tokyo
1974–1986         Assistant Professor, Department of Fisheries Resources, Ocean Research Institute, The University of Tokyo
1986–1994         Associate Professor, Department of Fisheries Resources, Ocean Research Institute, The University of Tokyo
1994–2000         Professor, Department of Behavior, Ecology and Observation Systems, Ocean Research Institute, The University of Tokyo
2000–2010         Professor, Department of Marine Bioscience, Ocean Research Institute, The University of Tokyo
2010–2013         Professor, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo
2013–2018         Professor, College of Bioresource Sciences, Nihon University
2013–present   Professor Emeritus, The University of Tokyo
2014–2020         Visiting Professor, Fukui Prefectural University
2018–2020         Specially Appointed Professor, Graduate School of Agricultural and Life Sciences, The University of Tokyo

1986    Japanese Society of Fisheries Science Achievement Award for Young Scientists in Fisheries Science
2006    Japanese Society of Fisheries Science Award
2007    Japan Prize of Agricultural Science, Yomiuri Prize for Agricultural Science
2011    Pacific Science Association Shinkishi Hatai Medal
2012    The Japan Academy Duke of Edinburgh Prize
2013    National Maritime Award (Prime Minister’s Prize)
2020    International Fisheries Science Prize
2022    Order of the Sacred Treasure, Gold Rays with Neck Ribbon

Dr. TSUKAMOTO Katsumi’s general area of interest is the “animal migration” that has fascinated people since ancient times, and he has focused his research especially on diadromous fish, which migrate between oceans and rivers. Through his work, he has built a scholarly foundation for understanding the basic principles of migration and the evolution of migratory behavior and advanced the biology of migratory fish. Early in his career, Dr. Tsukamoto discovered that Lake Biwa had two types of ayu (Plecoglossus altivelis) that follow two distinct migratory patterns. One type (large ayu) migrates up the lake’s tributary rivers and grows to a larger size, while the other (small ayu) spends most of its life in the lake and remains relatively small at the stage of reproduction. Determining that the two migratory patterns alternated by generation, Dr. Tsukamoto explained the mechanism sustaining this phenomenon in terms of a “switching theory.” He posited that the small ayu spawn earlier, so that their offspring are born earlier and tend to mature earlier, thus becoming large ayu, while the large ayu spawn later, producing offspring that remain small. This research won international acclaim for its explanation of life-history polymorphism, wherein organisms in a single population exhibit more than one life history. Dr. Tsukamoto also developed a groundbreaking fish tagging technique using otoliths (ear bone) and pioneered its application in fishery resource management and individual life-history estimation.

Dr. Tsukamoto’s most celebrated achievement is his discovery of the spawning grounds of the Japanese eel (Anguilla japonica), until then one of the greatest unsolved mysteries in the field of marine biology. Leading the world in the study of freshwater eels since the 1990s, Dr. Tsukamoto was ultimately able to put together a complete picture of the spawning migration of the Japanese eel, which had baffled humans since the dawn of history, and his achievement is recognized by researchers worldwide as a landmark in the history of science. The story of his amazing quest, which made innovative use of research vessels to strategically survey the vast North Pacific, has done more than anything in recent memory to convey to lay people the vision and passion that drives researchers in oceanography and biology. Dr. Tsukamoto’s team began its search for the spawning grounds of the Japanese eel in the 1970s. Hypothesizing that the eels spawned around the West Mariana Ridge in summer during the new moon, Dr. Tsukamoto developed a research cruise plan incorporating a new method for surveying vast areas of the ocean. In 2009 he proved his hypothesis when his team recorded the world’s first discovery of freshwater eel eggs in the wild. Since then, Dr. Tsukamoto and his many colleagues and students have continued to probe the mysteries of eel spawning migration, not only through their research cruises but also in the lab, incorporating otolith analyses and a wide range of physiological and other techniques.

Dr. Tsukamoto has also made important leading contributions to meeting educational and social challenges at the local and international level. He developed technology for artificial mass production of glass eel seedlings for use in aquaculture in order to ensure a stable supply of eels for human consumption and conserve wild eels. He established the East Asia Eel Society, forging private-public-academic partnerships throughout East Asia. He also wrote an essay titled Unagi no Nazo wo Otte [Pursuing the Mystery of the Eel] for a fourth-grade Japanese textbook (Mitsumura Tosho Publishing). In addition, he has traveled around Japan conducting classes that encourage elementary school students to think about reconciliation with nature. The Eel Caravan, as this program is called, has been held nearly 300 times nationwide. Among Dr. Tsukamoto’s outstanding achievements is his success in stimulating interest in marine conservation, not only among scientists inside and outside Japan but also among the general public and children.

In this way, Dr. Tsukamoto has not only made outstanding contributions to the advancement of the biology of fishes but has also, by sharing his own knowledge, experience, and philosophy, contributed more broadly to the harmonious and sustainable development of human society. In consideration of these achievements, Dr. Tsukamoto was judged the most suitable candidate for the “Biology of Fishes,” the research field for the 2022 Prize, and was therefore selected as the recipient of the 2022 (38th) International Prize for Biology.

Original articles

1. Tsukamoto Katsumi, Mari Kuroki, Shun Watanabe (2020) Common names for all species and subspecies of the genus Anguilla. Environmental Biology of Fishes 103, 985–991
2. Kuroki Mari, Michael J. Miller, Katsumi Tsukamoto (2014) Diversity of early life history traits in freshwater eels and the evolution of their oceanic migrations. Canadian Journal of Zoology 92, 749–770
3. Hatase Hideo, Kazuyoshi Omuta, Katsumi Tsukamoto (2013) A mechanism that maintains alternative life histories in a loggerhead sea turtle population. Ecology 94, 2583–2594
4. Tsukamoto Katsumi, Seinen Chow, Tsuguo Otake, Hiroaki Kurogi, Noritaka Mochioka, Michael J. Miller, Jun Aoyama, Shingo Kimura, Shun Watanabe, Tatsuki Yoshinaga, Akira Shinoda, Mari Kuroki, Machiko Oya, Tomowo Watanabe, Kazuhiro Hata, Shigeho Ijiri, Yukinori Kazeto, Kazuharu Nomura, Hideki Tanaka (2011) Oceanic spawning ecology of freshwater eels in the western North Pacific. Nature Communications 2, 179
5. Inoue Jun G., Masaki Miya, Michael J. Miller, Tetsuya Sado, Reinhold Hanel, Kiyotaka Hatooka, Jun Aoyama, Yuki Minegishi, Mutsumi Nishida, Katsumi Tsukamoto (2010) Deep-ocean origin of the freshwater eels. Biology Letters 6, 363–366
6. Tsukamoto Katsumi, Yoshiaki Yamada, Akihiro Okamura, Toyoji Kaneko, Hideki Tanaka, Michael J. Miller, Noriyuki Horie, Naomi Mikawa, Tomoko Utoh, Satoru Tanaka (2009) Positive buoyancy in eel leptocephali: an adaptation for life in the ocean surface layer. Marine Biology 156, 835–846
7. Tsukamoto Katsumi (2006) Spawning of eels near a seamount. Nature 439, 929
8. Tsukamoto Katsumi, Jun Aoyama, Michael J. Miller (2002) Migration, speciation, and the evolution of diadromy in anguillid eels. Canadian Journal of Fisheries and Aquatic Science 59, 1989–1998
9. Aoyama Jun, Mutsumi Nishida, Katsumi Tsukamoto (2001) Molecular phylogeny and evolution of the freshwater eel, genus Anguilla. Molecular Phylogenetics and Evolution 20, 450–459
10. Tsukamoto Katsumi, Izumi Nakai, Frederich W. Tesch (1998) Do all freshwater eels migrate? Nature 396, 635–636
11. Tsukamoto Katsumi (1992) Discovery of the spawning area for Japanese eel. Nature 356, 789–791
12. Tsukamoto Katsumi (1985) Mass-marking of ayu eggs and larvae by tetracycline-tagging of otoliths. Bulletin of the Japanese Society of Scientific Fisheries 51, 903–91120) Harris, J.M. and White, T.D. (1979) Evolution of the Plio-Pleistocene African Suidae. Monograph: Transactions of the American Philosophical Society, 69, Part 2: 1-128.

Review articles and books

13. Kuroki Mari, Martien J.P. van Oijen, Katsumi Tsukamoto (2013) Eels and the Japanese –An inseparable, long-standing relationship. In: Eels and Humans. Eds. Tsukamoto Katsumi, Mari Kuroki. Springer Japan pp. 91–108
14. Sudo Ryusuke, Katsumi Tsukamoto (2013) The onset mechanisms of the spawning migrations of Anguillid eels. In: Physiology and Ecology of Fish Migration. Eds. Ueda Hiroshi, Katsumi Tsukamoto. CRC Press, pp. 56–80
15. Kuroki Mari, Katsumi Tsukamoto (2012) Eels on the move-Mysterious Creatures over Millions of Years. Tokai University Press, 278 pp.
16. Tsukamoto Katsumi, Michael J. Miller, Aya Kotake, Jun Aoyama, Kazuo Uchida (2009) The origin of fish migration: the random escapement hypothesis. In: Challenges for Diadromous Fishes in a Dynamic Global Environment. Eds. Alex Haro, Katherine L. Smith, Roger A. Rulifson, Christine M. Moffitt, Ronald J. Klauda, Michael J. Dadswell, Richard A. Cunjak, John E. Cooper, Kenneth L. Beal, Trevor S. Avery. American Fisheries Society Symposium 69, 45–61
17. Tsukamoto Katsumi, Tae-Won Lee, Hans Fricke (2003) Spawning area of the Japanese eel. In:Eel Biology. Eds. Katsumi Aida, Katsumi Tsukamoto, Kohei Yamauchi. Springer, pp.121–140
18. Matsuura Keiichi, Sumadhiharga O. Kurnaen, Katsumi Tsukamoto (2000) Field Guide to Lombok Island-Identification Guide to Marine Organisms in Seagrass Beds of Lombok Island. Ocean Research Institute, The University of Tokyo, 499 pp.
19. Tsukamoto Katsumi (1995) Use of otolith-tagging in a stock enhancement program for masu salmon (Oncorhynchus masou) in Kaji river, Japan. In: Recent Developments in Fish Otolith Research. Eds. David H. Secor, John M. Dean, Steven E. Campana, Anne B. Miller, Belle W. Baruch. The University of South Carolina Press, pp. 403–422
20. Tsukamoto Katsumi, Rikizo Ishida, Kenji Naka, Takeshi Kajihara (1987) Switching of size and migratory pattern in successive generations of landlocked ayu. In: Common Strategies of Anadromous and Catadromous Fishes. Eds. Michael J. Dadswell, Ronald J. Klauda, Christine M. Moffitt, Saunders L. Richard. American Fisheries Society Symposium 1, 492–506