FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

While there are limited tuna resources in the ocean, the global market continues to have a strong demand for tuna. The use of captured juvenile tuna fish to develop offshore cage cultures of tuna has attracted worldwide attention. This study aimed to explore the short-term fattening of yellowfin tuna (Thunnus albacares) and investigate the growth rate, feed efficiency, and crude fat content of tuna under cage culture. After tuna were cultured in a cage for 12 months, the body weight of a 1-kg juvenile yellowfin tuna reached 9-10 kg, with a 0.65-0.75 kg increase per month. The fork length of the tuna reached 80-82 cm, with a 1.24 mm increment per day. Specific growth rate (SGR) was 0.66%-0.80%, and feed efficiency was around 10%. The crude lipid levels of 2-3 kg yellowfin tuna cultured for one month and 5-6 kg yellowfin tuna cultured for seven months were 2.2% and 11.6%, respectively. The crude lipid levels of the fish cultured for seven months were 10 times higher than those of wild fish. The results of this study will contribute to the development of yellowfin tuna offshore cage cultures in Taiwan, which is achieved through the use of the abundant resources of juvenile yellowfin tunas in the surrounding waters of Taiwan. This will supply markets with high-quality sashimi-grade fish, improve the prices of yellowfin tuna products, and promote the development of yellowfin tuna aquaculture technologies, which will contribute to tuna resource conservation efforts.