News Letter Vol.7
Kinki University 21st Century COE Program English Site > News Letter Vol.7
21st Century COE Program 'Center for Aquaculture Science and Technology for Bluefin Tuna and Other Cultivated Fish'
A detailed introduction to and the current status of the research activities of the Seedling Production and Culture Group

Osamu Murata (Seedling Production and Culture Group, Fisheries Laboratory)

As was reported in the previous volumes of this News Letter, our Group is devoted mainly to breeding, covers a wide range of research activities, and works at four sites, that is, the three test sites of Fisheries Laboratory in Shirahama, Uragami, and Oshima, and the Graduate School of Agriculture, with half of the COE members assigned to our Group.

[ Mature and oviposition ]
In order to produce seedlings systematically, it is essential to obtain quality ovum from parent fish steadily, but many problems remain with respect to bluefin tuna. Thus, with a view to elucidating conditions for mature and oviposition, we record water temperature at the fisheries in both Kushimoto-oshima and Amami-oshima all year round and have continued an investigation of the development of the reproductive gland, accumulated water temperature, and the status of parent fish's oviposition. According to the investigation conducted so far, water temperature ranges between 14 and 28 degrees centigrade at Kushimoto-oshima and between 19 and 29 degrees centigrade at Amami-oshima. The reproductive gland develops most from July to September, and during the past three years, oviposition was not observed at Kushimoto-oshima in 2005, but was observed every year at Amami-oshima. It was estimated that accumulated water temperature was around 4,000 hours when oviposition started.

[ Ovum development and quality ]
We endeavor to accumulate knowledge important for realizing the isolation, preservation, and subrogate production of primordial germ cells (PGCs) in order to maintain the future genetic diversity of bluefin tuna culture groups. With a view to understanding the morphogenetic process of bluefin tuna, we are tracking cleavage, coating, the formation of the embryonic body, the formation of the somites, etc., using microscopic pictures and tissue pictures, and are also studying the migration path of PGCs on the basis of this knowledge. Also, in order to establish economical and stable seedling production technology, we are studying reasonable qualitative evaluation methods for gametes and the embryo, maturity control methods for producing quality gametes in accordance with this index, artificial insemination methods, methods for preserving gametes, methods for breeding the early embryo, etc.

[ Seedling production ]
One of the causes of mass mortality in artificially incubated bluefin tuna at the larval stage is bottoming, i.e., larvae sink to the bottom of the tank. With a view to analyzing the mechanism of this mass mortality, we elucidate changes in the capacity of the air bladder and the body specific gravity of larvae as they grow and diel variation, and examine measures to reduce initial depletion. We also conduct fundamental research in an effort to elucidate the mechanism of the accumulation of fat in the muscles, the most important factor of bluefin tuna's flesh quality, and develop technology for controlling the accumulation. As a result, we have identified the variance in fat accumulation in artificially incubated bluefin tuna at the larval stage which is caused by the breeding water temperature. The conventional seedling production method has involved a mass mortality of 40% to 70% in larvae in several days immediately after offshore transfer or transportation. When we examined the causes of mass mortality including collision death occurring under various circumstances and methods for preventing such mass mortality, we found that substantial effects can be obtained by using stimulation mitigating transparent material etc. as the wall of a small tank that is used temporarily, by adding high-contrast patterns to the wall of a large tank or net preserve in which larvae are bred or transported, and by preventing a decline in the visual function at night or in dim light by electric illumination. This year, we will not only improve these further, but also study the visual function by a new method to investigate in more detail the causes of mass mortality occurring under various circumstances. We also want to elucidate in detail why certain bluefin tunas feed on one another and develop a prevention method.

Thus, we will remain devoted to research activities this year so that we can commercialize mass production technology for bluefin tuna seedlings within several years.

Implementation of the 2006 academic year COE tuition exemption/reduction program and the scholarship program

Hiromi Ohta (COE Special Director, Graduate School of Agriculture)

This is the third year after Kinki University introduced its own tuition exemption/reduction and scholarship programs for graduate school doctorate course (DC) and master course (MC) students at the COE. The former program grants a 50% tuition reduction and a full exemption to 25 MC students and ten DC students, respectively. The COE Promotion Committee reviews and screens the applicants on the basis of the research plans and TOEIC certificates submitted by them, the recommendations of their tutors (responsible for business promotion), etc., and President makes a decision at the recommendation of the Graduate School Director. In addition to this program, a scholarship of 100,000 yen a month is granted to five DC students as a measure to develop personnel at this education site who will take the lead in world-class research.

This year, 27 MC students applied for the tuition exemption/reduction program, of which 25 were selected. Among the 17 DC students affiliated with the COE, ten were granted a tuition reduction or exemption and five were selected for scholarship.

TOPICS

A number of prizes received for the 'Full culture of bluefin tuna'

The Fisheries Laboratory of Kinki University received the Agriculture Minister's Prize for the 'Achievement of full culture of bluefin tuna' at the 2004 ceremony for commending persons in the private sector who have attained distinguished achievements in research and development in agriculture, forestry, and fisheries (as reported in Volume 3 of this News Letter). On February 2, 2005, the 2005 Nikkei Excellent Products and Services Award Ceremony was held under the sponsorship of Nihon Keizai Shimbun at the main building of Hotel Okura Tokyo. A-marine Kindai Co., Ltd., a university-launched venture, received an outstanding performance award (Nikkei Sangyo Shimbun Prize) for the first shipment of 'Fully cultured tuna', which has been researched and developed by the Kinki University Fisheries Laboratory for 32 years, and other achievements. This ceremony marks the 130th anniversary of the publication of Nihon Keizai Shimbun, and 250 out of 20,000 products and services were nominated and 46 of them, including 'Full cultured bluefin tuna', were given awards. The markets for this tuna, which were initially departments stores and hotels in the Keihanshin area, have been expanded to include Mitsukoshi at Nihonbashi, Tokyo. Furthermore, the marketing campaign conducted under the slogan of food safety and security was rated high, which included the attachment of 'Graduation certificates' containing QR codes to the shipped fish and the provision at a website of information such as the time and place of incubation and the type of the feed given.

On March 15, 2006, the 2005 New Business Award Ceremony was held under the sponsorship of the Japan New Business Conference Federation and the Kanto New Business Conference, giving an outstanding performance award to A-marine Kindai Co., Ltd. The reasons for the award were that (1) this is the world's first full culture of tuna, so novelty as a pioneer in the culture fishing can be observed, (2) full culture of tuna succeeded and was commercialized after 30 years' research and development, so high-level innovation can be observed, (3) it can be expected that a new business model will be established by entry into new fields such as tourism. These awards encourage us to promote the COE Program 'Center for Aquaculture Science and Technology for Bluefin Tuna and Other Cultivated Fish', while urging us to work even harder. (Osamu Murata)

Mini-symposium by Japan Society of Fisheries Science

Japan Society of Fisheries Science held its fiscal 2006 assembly at Kochi University from March 29 to April 2, 2006. On the first day, a mini-symposium 'Initial growth of bluefin tuna and seedling production: — The current status and prospects — ' was held. Various research presentations were given by a number of research institutes, including Professor Kenji Takii, Kinki University Fisheries Laboratory and COE Program Member, who gave a report on 'Palate responses and feeding of larval fish' together with Professor Jun Kamihara, Mie University. Also, Associate Professor Yoshifumi Sawada, Fisheries Laboratory, gave a presentation on 'The development of the external form and organs', Professor Shigeru Miyashita, Fisheries Laboratory, gave a report on 'Surfacing and bottoming death in seedling production', and Associate Professor Yasunori Ishibashi, Graduate School of Agriculture, talked about 'Collision death in seedling production'. All of them gave presentations on the latest research results, receiving high appraisals from the audience.