1961 PhD, Faculty of Agriculture, University of Tokyo. Chemical structure and physiological activity of nereistoxin.


1972 Achievement Award for Young Scientists in Fisheries Science from the Japanese Society of Fisheries Science; 1982 The JOS (Oceanographic Society of Japan) Prize;

1993 Japan Prize of Agricultural Science (Environmental Scientific Research on Red Tide Occurrence); 1993 Yomiuri Agricultural Prize; 1995 Medal with Purple Ribbon, Prime Minister of Japan; 1999 Kagawa prefecture Person of Distinguished Cultural Merit; 2003 The Order of the Sacred Treasure, Gold and Silver Star, Prime Minister of Japan.

Professional Career

1964 Associate Professor; 1978 Professor; 1983 Dean, Faculty of Agriculture, Kagawa University; 1991 President, Kagawa University; 1997 Emeritus Professor, Kagawa University; 1997-1998 Professor, Faculty of Engineering, Tokushima Bunri University; 1998-2000 Director, Kagawa Study Center, The University of the Air (Open University of Japan); 2000-2009 Director, Research Institute for the Seto Inland Sea.

Key HAB Contributions

Prof. Tomotoshi Okaichi (“Tom” to his non-Japanese friends), has been a pioneer in the environmental protection of enclosed seas, such as the Seto Inland Sea, and the management and mitigation of harmful algal blooms. Triggered by a serious Chattonella antiqua red-tide induced aquaculture fish-kill in 1973 in the Seto Inland Sea (US$ 0.5B loss), Prof. Okaichi became the chief investigator of a major red tide research project carried out from 1978-1984 involving more than 30 scientists and funded by the Ministry of Education,Science and Culture. He led various scientific oceanographic studies investigating N and P loading from various industry sectors in relation to nutrient concentrations in the seawater, pointing out the relation between increased frequency of red tides and the expansion of eutrophication. Subsequently, he instigated local and central governments to introduce pollution control regulations of N and P in waste water from municipalities and factories. He therefore has been not only a pioneer scientist but also a pioneer in successfully applying scientific knowledge for the better management of coastal seas.

Prof. Okaichi was the early leader of the WESTPAC/IOC/UNESCO program on Toxic and Anoxic Phenomena associated with Algal Blooms in the WESTPAC region allowing Japanese scientists to take part in overseas collaborative red tide research (notably in South-East Asia) supported by the Japanese Society for the Promotion of Science. He organized the first WESTPAC Training Workshop on Red Tides in Bangkok in 1985, which became a model for numerous later training activities in the region. Prof. Okaichi effectively transferred the Japanese experience to an international audience by hosting the first International Symposium on Red Tides in Takamatsu in 1987, a memorable meeting which attracted 260 scientists including 90 from overseas. He subsequently became the leader of an interdisciplinary study on sustainable production of valuable fishes and preservation of the environment in the Seto Inland Sea from 1992 to 1995, sponsored by the Nippon Life Insurance Foundation. Prof. Okaichi’s books on Sustainable development in the Seto Inland Sea, Japan (1997) and Red Tides (2004) are shining examples of the vision, drive and dedication by a leading environmental scientist devoted to protecting an increasingly degraded planet.

Prof Okaichi worked almost all his entire scientific life at Takamatsu, Kagawa, which faces the Seto Inland Sea. He rejected invitations of positions at other universities as he was of the strong opinion that a university must contribute to the region where it is located. Even in retirement he continues serving the local community, still working as Chairman of the committee on Environmental Conservation of Kagawa Prefecture, adviser of the Red Tide Institute of Kagawa Prefecture, and involved in the 2010 Setouchi International Art Festival held around islands of the eastern Seto Inland Sea.


Yasuwo Fukuyo, Masaaki Kodama, Ichiro Imai , Kazumi Matsuoka, Sadaaki Yoshimatsu.

10 Key HAB publications

Okaichi, T. (ed) 2004. Red Tides. Ocean Sciences Research vol. 4. Terra Scientific Publishing Company, Tokyo, Kluwer Academic Publishers, Dordrecht, 439 pp.

Okaichi, T. and T.Yanagi (eds). 1997. Sustainable development in the Seto Inland Sea, Japan. Terra Scientific Publishing Company, 329 pp.

Okaichi, T., T. Ochi, S. Wissesang, T. Ishimaru, Y. Fukuyo, K Tada and T. Urai (1991) Isolation and culture of Pedinomonas noctilucae, a symbiont of Noctiluca scintillans of Gulf of Thailand. Proceedings of the Second WESTPAC Symposium, organized by Ministry of Science, Technology and Environment of Malaysia Intergovernmental Oceanographic Commission (IOC, UNESCO), p.166-176.

Okaichi, T., S. Montani, T. Lirdwitayaprasit, C. Ono and S. Yoshimatsu (1990) Counter measures aimed at the Chattonella red tide in Shido Bay, the Seto Inland Sea in 1987. The Second Asian Fisheries Forum (Hirano, R. and I. Hanyu eds.), Asian Fisheries Society, Manila, p.895-898..

Okaichi, T., D.M. Anderson & T. Nemoto 1989. (eds). Red Tides: Biology, Environmental Science and Toxicology. Elsevier, New York, 489 pp.

Okaichi, T., , S. Montani, J. Hiragi and A. Hasui (1989) The role of iron in the outbreaks of Chattonella red tide. Red Tides - Biology, Environmental Science and Toxicology, (Okaichi, T., D. M. Anderson and T. Nemoto eds.), Elsevier, New York, p.353-356.

Okaichi, T., T. Ochi, H. Takano, K Matsuno, T. Morimoto, T. Murakami and M. Shimada (1989) The cause of fish kills associated with red tides of Chattonella antiqua (Hada) Ono. Current Topics in Marine Biotechnology (Miyachi, S., I. Karube and Y. Ishida eds.), The Japanese Society for Marine Biotechnology, Tokyo, p.185-188.

Shimada, M., T. H. Murakami, T. Imahayashi, H. S. Ozaki, T. Toyoshima and T. Okaichi (1983) Effect of sea bloom, Chattonella antiqua, on gill primary lamellae of the young yellowtail Seriola quinqueradiata. Acta Histochemica et Cytochemica, 232-244.

Okaichi, T. and Y. Imatomi (1979) Toxicity of Prorocentrum minimum var. mariaelebouriae assumed to be a causative agent of shortnecked clam poisoning. Toxic Dinoflagellate Blooms. Proceeding of the Second International Conference on Toxic Dinoflagellates Blooms (1978), Elsevier, North Holland. p.385-388.

Okaichi, T. and Y. Hashimoto (1962) The structure of nereistoxin. Agricultural and Biological Chemistry 26, 224-227.



Prepared by Y.Fukuyo and G. Hallegraeff.