March 31, 2015
A yellowfin tuna swims in an aquarium in Panama 17 meters long and 5.8 meters deep.
Bluefin tuna, called “hon maguro (1)” in Japan, is a popular fish for sushi and sashimi. Eighty percent of bluefin tuna is consumed in Japan. As for yellowfin tuna, it is in high demand around the world as canned tuna and also is consumed as sashimi. Yellowfin tuna accounts for 65 percent of the total catch of tuna. There is deep concern about depletion of both species due to overexploitation.
In 2002, scientists at the Kinki University succeeded in closing aquaculture cycle of the bluefin tuna for the first time in the world. The Japan International Cooperation Agency (JICA) has been cooperating with a science and technology cooperation project under the Science and Technology Research Partnership for Sustainable Development (SATREPS) scheme (2) in Panama since 2011 in association with the Japan Science and Technology Agency (JST), aiming to apply this technology and experience for the aquaculture of yellowfin tuna, the most caught tuna species.
On Nov. 17, 2014, the International Union for Conservation of Nature and Natural Resources (IUCN) published the Red List (3), where Pacific bluefin tuna was listed in the category “vulnerable.” It is pointed out that this category change for Pacific bluefin tuna from “light concern” to “vulnerable” comes from its increased consumption in economically expanding Asian countries. Catching fish before they spawn has led to a loss of breeding opportunities, which is the cause of the decrease in number.
To keep tuna on dining tables, the development of fisheries management and breeding technology has been promoted in Japan. In one such effort, Kinki University researchers achieved full-cycle aquaculture, a cycle of spawning fish raised from artificial hatching, and then artificially hatching again. Unlike with raising juvenile fish caught in the wild, recycling-oriented technology is applied to avoid placing a load on marine resources. And today, a business project including collaboration with a major trading firm is underway.
A researcher from Kinki University teaches management of feed for yellowfin tuna in a laboratory.
Living in tropical marine waters, the yellowfin tuna has yellow dorsal fin and tail fin, the source of its name. It is categorized as “near threatened,” one level lower than “vulnerable.”
In Central and South American countries the export of yellowfin tuna, which are found in tropical marine waters, caught in the surrounding sea is an important source of foreign exchange. Among those countries, Panama is the second in fish catch on the eastern Pacific coast after Mexico and is also the port of transfer of tuna caught by other countries’ fishing boats. Panama is playing an important role in terms of tuna resources management. Also, on the southern Pacific coast of Panama is the only research institute in the world carrying out research related to biological findings valuable for resource management of tuna, Achotines Laboratory (4).
Kinki University, Aquatic Resources Authority of Panama (ARAP) and Achotines Laboratory/IATTC are working together under SATREPS research program on a project called “the Comparative Studies of the Reproductive Biology and Early Life History of Two Tuna Species for the Sustainable Use of These Resources,” to reveal scientific findings (spawning biology and early life-stage history) required for the protection of yellowfin tuna and bluefin tuna, as well as for accumulation and integration of the findings.
To a certain extent the biology of the bluefin tuna has been becoming clearer through investigations into aquaculture by Kinki University, but large parts of its biology are still yet-to-be-defined because in general it is difficult to make contact with tuna living offshore or in the open ocean.In this sort of research, it is necessary to investigate several types of fish, since research on one type only makes it difficult to figure out the implications of the particularities of physiological biology being clarified.
In concrete terms, spawning and breeding status are recorded daily to advance the understanding of biology. At the same time, researches on filiation using DNA and on the procreation system are being carried out. Research on feed useful for the aquaculture of yellowfin tuna is also being carried out, and data on raising eggs and juvenile fish under different environments have been collected.
Professor Yoshifumi Sawada explains the project to members of the media.
A Panamanian researcher transfers juvenile fish into a large aquarium.
“Kinki University has a research record on bluefin tuna, but since yellowfin tuna is from a different strain, technology and experience for bluefin tuna is not really applicable directly. Experimentation on breeding tuna is hard work, requiring all-night observation, diving in fish preserves and breeding work in which you must continually observe for long periods, but the idea of creating brand new technology for yellowfin tuna has permeated the collaborative research in Panama, and we are working with excitement toward the goal of implementing the results of our research in society (giving back to society)”, said Yoshifumi Sawada, professor of the Fisheries Laboratory, Kinki University, the representative of the Japanese side of the project.
On another front, Amado Cano, leader of the project counterparts from the Aquatic Resources Authority of Panama (ARAP), said that “One outcome from the collaborative research is the capacity development of young scientists specializing in aquaculture, of whom there was a small number in Panama. The Panamanian fishery industry will be stimulated by this.” Expectations are focused not only on the outcome of the research, but also on the impact on the future Panamanian fishery industry. To protect our future dining tables, efforts toward revealing the biology of yellowfin tuna are based on quiet dedication and a relationship of trust between Panama and Japan.
The most difficult part in full-scale aquaculture is the stage from artificial incubation to raising to juvenile fish. The project has already achieved this. On Nov. 27, 2014, an operation was showed to Panamanian and Japanese media involving the transfer of some 10 juvenile fishes into a large aquarium. The fishes were bred and then raised up to 6 centimeters.
For next spring, a release into a sea cage installed offshore is planned in order to realize full-scale aquaculture. The project will be continued until 2016.
1. There are two types of bluefin tuna, Pacific bluefin tuna found in the Northern Pacific Ocean including Japanese coastal waters, and the Northern Atlantic Ocean bluefin tuna found in Northern Atlantic Ocean. “Bluefin tuna” is used in this article to mean Pacific bluefin tuna.
2. Science and Technology Research Partnership for Sustainable Development
3. A list of animals and plants in danger of extinction evaluated by several specialists and categorized in “Extinct” “Threatened” “Near Threatened” and “Data Deficient.” In the latest Red List, 22,413 strains accounting for 29 percent of overall total of evaluated strains (76,199) were categorized as “Threatened.”
4. Organized by the Inter-American Tropical Tuna Commission (IATTC), an organization which is taking charge of international management of tuna resources in the East Pacific Coast area.