Taiwan Today

Researchers under the Cabinet-level Council of Agriculture are making great strides toward the breeding of yellowfin tuna in captivity in Taiwan, according to council officials. According to the Tungkang Biotechnology Research Center under the COA’s Fisheries Research Institute, research on raising yellowfin tuna is entering a critical phase, with domesticated yellowfin set to mature and lay eggs next year. This will be very helpful to research on how to breed the species in captivity. A COA spokesman said with an eye to the economic value of yellowfin tuna, many nations around the world have begun work on raising it. Japan began from raising eggs, but that process requires 10 years or more; Australia and some Mediterranean nations decided to first catch fry from the wild, and then place them into an intensive short-term feeding program. Taiwan is also beginning from the fry stage, and the Aquacultural Experimental Station has established an experimental setup in Pingtung. If this system is successful, it will be expanded throughout the east coast area. Six years ago, the Tungkang Biotechnology Research Center began work on the artificial raising of yellowfin tuna. In the early stages, the ponds were too shallow and the scope of the project too small, and the yellowfin were likely to be injured and die. Last year, an additional investment of NT$10 million (US$310,000) was provided for new ponds, each 18 meters in diameter and six meters deep. These ponds can hold 1,500 tons of water, giving the fish a larger space in which they can move more quickly. The results have shown improvement, and next year the yellowfin should be laying eggs, an important step toward raising the fish. Research center director Chen Tzy-ying said the yellowfin tuna are being raised both on land and in box nets off the coast of Hengchun and Xiaoliuqiu. Artificially bred fish have a higher oil content as sashimi and are tastier, but because the technology to raise them is not yet mature, and costs are too high, the project is still firmly in the experimental phase, and has not yet entered into mass production. Dr. Li Yan-hong devotes his research to the question of raising yellowfin tuna. He said they are quite intelligent, have good vision and swim rapidly, sometimes reaching 70 to 100 kilometers per hour. However, their bodies are fragile, and a simple bump can cause external injuries that can easily lead to death. In the evening, when the fish sleep, they continue swimming, and although their speed is reduced and their alertness keen, loud noises can frighten them and cause fatalities. Moreover, the yellowfin need very good water quality to live, and if the water becomes too cloudy, the fish may perish. As a result, culture in box nets is limited by a number of factors. Li said at present he is raising 53 yellowfin tuna that he has been feeding since they were tiny. Some have been with him as long as four years, and others as little as two. He uses frozen feed made of shrimp and mackerel, and plans to allow the mature fish to breed naturally in the pond next year. However, his project has been impacted by cuts to research funding, and progress has been somewhat slower than originally planned as a result. Li emphasized that yellowfin tuna are numerous and easy to catch, and are the easiest of the tuna varieties to research. The Aquacultural Research Center also plans to do work with bigeye tuna in Taitung. However, the technical challenges involved in raising blackfin tuna are too great, and there are no plans afoot to move into aquacultural research involving that species. (This article first appeared in the “Liberty Times” Nov. 30, 2009.)