Opinion JapaneseEnglish

Researching Deep-Sea Fish Larvae and Juveniles Living in Suruga Bay

September 2 , 2019

The oceans surrounding Japan are home to a rich array of aquatic life, which are an important source of nutrients for human beings. There are still many bio-resources in the sea, however, that we know nothing about. Professor Atsushi Fukui is the leading scientist in the field of deep-sea fish larvae and juveniles. He studies deep-sea fish living right off campus in Suruga Bay, the perfect environment for his research.

Interviewer: Masayoshi Nakane


“To catch and research fish that no one else has caught”

Question: What led you to study the larvae and juveniles of deep-sea fish?

Answer: When I was young, every year we would spend the summer in Okitsu, which is in Katsuura, Chiba Prefecture, and I would swim, fish, and explore the tide pools. This was a formative experience. Since 1998, I’ve done research in Suruga Bay, one of the world’s preeminent deep bays. I realized there were many taxa of deep-sea fish for which we know next to nothing about their larvae and juveniles, so I thought, “This is what I want to do,” and began my current research.



Q: What stages in the growth of a fish are larvae and juveniles?

A: Fish have fins, and fins have fiber-like fin rays. A fish is a larva until the number of fin rays in all its fins is equal to that of an adult fish. Juvenile is the stage between larva and a fully grown adult.


Q: Catching larvae and juveniles must be an incredibly difficult task. You would have to know the topography of the seafloor.

A: It is extremely difficult to tow a larval net just above the seafloor. If the net gets snagged on the bottom, you stand to lose your collecting equipment. But if you play it safe and keep the net a good distance from the bottom, it defeats the purpose. Initially, I started at a depth of 20 meters underwater, but that didn’t really work, so over the eight years since I started, I’ve been able to lower the net to depths of 200 meters to 1,000 meters, just above the seafloor.

Since 2012, I’ve taken on the challenge of Suruga Trough, the core area. I’ve updated my collecting equipment and in my research now I aim close to the seafloor at a depth of 1,400 to 2,200 meters. The total distance that I’ve towed larval nets in Suruga Bay to date exceeds 1,000 kilometers. My research lab has a motto: “To catch and research fish that no one else has caught.”


New species discovered by Prof. Fukui’s research group

Q: I heard that you’ve announced 10 new species of fish.

A: They were all previously unrecorded species that we discovered in the process of researching larvae and juveniles. Categorization is conducted based on adult fish, but we approach it from larvae and juveniles, which allows us to discover and solve previously hidden problems. For three years in a row now, at a rate of once a year, students in the doctoral program have announced new species of snailfish (Liparidae) gathered from Suruga Trough. It’s no exaggeration to say that Suruga Bay is itself part of the campus of the university’s School of Marine Science and Technology. For people who like the ocean, who like living creatures, and are passionate about doing fieldwork, there is no better environment. I encourage you to knock on the school’s door.

Professor, Department of Fisheries, School of Marine Science and Technology

Atsushi Fukui

Born in Tokyo in 1957. Graduated from Tokai University’s School of Marine Science and Technology in 1980. Completed a master’s degree program at Kagoshima University’s Graduate School of Fisheries and earned a doctorate degree from the University of Tokyo’s Graduate School of Agricultural Sciences. Hired by Tokai University in 1998 and appointed to current position in 2004. Academic affiliations include the Ichthyological Society of Japan, the Japanese Society of Fisheries Science, and the Japanese Society of Fisheries Oceanography.