News Letter Vol.3
Kinki University 21st Century COE Program English Site > News Letter Vol.3
Kinki University Fisheries Laboratory receives the Agriculture Minister's Prize for the full culture of bluefin tuna

On November 26, Kinki University Fisheries Laboratory (represented by Director Hidemi Kumai) 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, held at Hoso Kaikan in Tokyo under the sponsorship of the Ministry of Agriculture, Forestry and Fisheries and Agriculture, Forestry and Fisheries Technical Information Society.

This commendation project was started in 2000 to contribute toward giving further motivation to those especially in the private sector who engage in research and development in the fields of agriculture, forestry, and fisheries since the prospects for these and other related industries in Japan in the 21st century show that it is critical to make all-out efforts at research and development in these fields. The prizes include the Agriculture Minister's Prize and five other prizes.

Kinki University Fisheries Laboratory is the first fishery-related institute to receive the Agriculture Minister's Prize. The evaluation of its achievement was that (i) the establishment of full culture technology for bluefin tuna, which is consumed much by the Japanese people and is expected to decrease, is highly significant and (ii) although this epoch-making technology has not been spread widely, much can be expected from it.

At the ceremony, Director Kumai gave a presentation of the achievement, and panels and a stuffed specimen of bluefin tuna which was raised for 23 years were exhibited. At the celebration and opinion exchange meeting, sashimi of a full-cultured bluefin tuna was offered and the participants admired it for its flesh color and taste.

Receiving a prize certificate. Trophy for the Agriculture Minister's Prize

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 at the Environmental Conservation and Source Dynamism Group

Takeshi Yamane (Source Dynamism, School of Agriculture)

Symposium poster
First of all, I would like to explain about the research themes currently pursued by the members involved in source dynamism.

The research themes cover a wide range of subjects, including the collection and analysis of biological information using a data logger which provides a basis for the analysis of source dynamism; biomechanics; aestho-physiology; the ocean structure and the distribution of populations in time and space, based on satellite information; the mechanism of death by collision in culture preserves, which is critical to the culture industry; a theoretical net preserve design model.

International Symposium 'Stock Enhancement and Aquaculture Technology', planned and administered by the Environmental Conservation and Source Dynamism Group, was held from November 10 to 11. Outlined below are the research themes presented at the symposium by post-doctoral fellows (1, 2) and graduate students (3, 4, 5).

1. HOLGER KORTE (Germany)
Inertia transformation in fishing net calculations.

The development of visual acuity in bluefin tuna.

Application of NaLA, a fishing net configuration and loading analysis system, tuna net - cage.

Fluid dynamics of bluefin tuna based on CFD analysis.

An acceleration data - logger provides new information on swimming bluefin tuna in a net cage.

Mitsuru Eguchi (Environmental Conservation, School of Agriculture)

The Environmental Conservation Group's research and education activities center around the following four themes. (1) Environmental conservation in culturing preserve waters: Self-pollution in preserve culture sites on the surfaces of seas has long been a problem, but adequate environmental conservation measures are not established yet. In this context, we are trying to make an accurate estimate of the burden placed by the human economic activity of preserve culture upon the environment of fish culturing waters, elucidate the physical circulation and water quality formation processes in the waters in physical, chemical, and microbial ecological terms, and suggest measures necessary for environmental conservation and restoration. (2) Analysis of the behavior of cultured fish in response to environmental changes: We are trying to understand the impact of environmental changes in the waters upon the behavior, physiology, maturity, and food intake of fish in preserves, through simultaneous analysis of environmental information and life behavioral information by the use of data loggers and biotelemetry. (3) Conservation of on-land breeding environments at seedling production sites: With a view to realizing stable seedling supply, which is an essential condition for establishing stable and sustainable fish culture, we conduct dynamic analysis of the quality of seedling breeding water and microbial communities (including feed lives) to establish breeding water control methods which will prevent mass mortality in juvenile fish. (4) Elucidation of the mechanism of the survival of fish disease microbes in natural waters and the infection route: The major cause of mass mortality in cultured fish in natural waters tends to be viruses, bacteria, parasites, and other pathogenic microbes. While many studies have been done on fish diseases, our Group is trying to elucidate how pathogenic microbes survive in natural waters and how the diseases are communicated, with a view to establishing measures to prevent the occurrence of fish diseases. Both themes are being pursued in close coordination with the Seedling Production and Culture and other research groups, and are being promoted steadily.

Current status of a bluefin tuna culture manual development project

Shigeru Miyashita (Chair of the cross-group project, Fisheries Laboratory)

[ Purpose ]
Floating-Type Tuna Preserve
Since bluefin tuna culture requires large facilities and comparative experiments are difficult, bluefin tuna culture technology has been developed through trial and error and through experience, and few reports are available. Fundamental technology itself is not established yet, including the relationships between physicochemical environments including the structure and size of preserves, the type of feed and the feeding rate, and the effects of culture, such as feed efficiency, growth and flesh quality (market evaluation). And all feed for this species is living feed as formula feed is not developed yet. Under the circumstances, we have to work with low efficiency and pay high feed transportation and storage costs, and it is difficult to maintain steady flesh quality and promote the development of improvement technology. Therefore, the development of formula feed is an imperative. These issues are critical to bluefin tuna culture today and should be resolved immediately as the sharp rise in imports has pushed down the market price and has increased the need for cost reduction.

Then, we launched a cross-group project in fiscal 2004 with a view to securing systematic coordination among the research groups at this site for culture, environment and behavior, feed, nurture and flesh quality, and distribution and economics, etc., investigating the impact of physicochemical environments, feeding methods, etc., upon the effects of culture, developing a culture manual for this species, and commercializing formula feed. We created test preserves in two totally different environments, Oshima, Kushimoto, Wakayama Prefecture and Amami-oshima, starting an experiment in June. This large-scale experiment was implemented with the financial assistance of the university as the budget for this site is not large enough to cover it.

[ Methodology ]
Contain 865 bluefin tuna (average weight of approximately 15kg) in a 30m-diameter preserve at the Oshima test site and 1,100 (average weight of approximately 12kg) in a 35m-diameter preserve at the Amami test site, feeding them twice a day until satiation, and investigate the impact of the fishery environment upon growth and flesh quality. Also, create, at the Amami test site, two 16m-diameter preserves (each containing 50 of the same fish for test purposes) for which different feed rates are set, making a comparison with Oshima and investigating the impact upon growth, flesh quality, etc., of the differences between this preserve and the large preserve mentioned above in terms of physical environments, such as the shape and volume of the preserves, and fish behavior.

[ Status of the experiment and enormous damage by typhoon No. 18 ]
Taking up fish killed in typhoon
Started on June 25, this experiment stayed on track without mortality, after the behavior group successfully implanted data loggers at the beginning of July. However, in September, just before the second sampling, Amami-oshima was hit by typhoon No. 18 and was exposed to the storm zone for forty-eight hours from the morning of September 5. In particular, the area around the test site (Keten) was subjected to torrential rains exceeding 400mm (precipitation in Koniya was 192mm), which caused landslides at several prefectural roads and forest roads. When we checked the preserves after the typhoon went away, we found that the facilities were not damaged but almost all of the bluefin tuna under test were killed. We experienced a number of typhoon in the past, but this is the first time we suffer damage. We determined that the cause of death is murky water caused by landslides since no abnormality was found with parrot fish raised at the same place. In the three preserves used for this experiment, 1,016 and 84 were killed, respectively (average weight of 18kg) and damage totaled approximately 50 million yen. In addition, almost all of the parent fish kept in four preserves, including the ones being raised (aged between 2 and 6 years and weighing between 4kg and 250kg), were killed (677 were killed and damage totaled approximately 140 million yen). As a result, we confirmed that the survivors in the test preserves were only ten in the large preserve and ten and 16 in the two small preserves, respectively. Judging it impossible to continue the experiment, we put all the survivors together in one preserve and conducted only the behavior group's research with implanted data loggers. The other experiments were suspended until fiscal 2005.