Analysis on technology of bluefin tuna aquaculture in Japan and its enlightenment to the development of bluefin tuna industry in China

【Objective】By analyzing the key technologies of bluefin tuna aquaculture in Japan，this study aimed to provide reference for promoting the test breeding of bluefin tuna in China in an orderly way，so as to accelerate the formation of new quality productive forces matching aquaculture conditions in China.【Method】Analyed the key technologies and challenges in fully artificial breeding of bluefin tuna aquaculture in Japan，considering technical progress of bluefin tuna aquaculture in China，this paper proposed suggestions for the development of bluefin tuna industry in China.【Result】 From the perspective of breeding methods，Japan adopted long-term breeding and full-cycle breeding. Long-term breeding involved using natural fries of 100-500g captured in the spring and summer that migrated to the coast of Japan， which were raised in offshore facilities until they reached 30-60 kg before being sold. Full-cycle breeding relied on fully artificial breeding techniques，under which natural female fish were induced to spawn，which were then fed until maturity and the second generation of female fish were successfully induced to spawn. Fry production was the most technically challenging part of the full-cycle breeding of bluefin tuna. During the initial stage of breeding，the number of fertilized eggs were monitored and strict density control was required. Mature eggs with a diameter of about 1 mm were extracted from 4-year-old to 6-year-old female fish for fertilization，and the proportion of 1 million fertilized eggs into 50-100 t of water was placed in onshore facilities. Eletrolyzed seawater could be used as a disinfectant to remove the nerve necrosis virus from the fertilized eggs and improve the activity of fertilized eggs. Feeds such as rotifer，other juvenile fishes and surimi were fed to bluefin tuna in different growth stages. In addition，it is necessary to overcome the technical difficulties of artificial fry production，such as fry floating and sinking mortality，cannibalism，bumping into a net cage，and difficult in over-wintering.【Suggestion】China should launch pilot projects for bluefin tuna aquaculture as soon as possible，grasp the main line of scientific and technological research，and effectively give full play to the role of national marine ranching demonstration zones and the industrial revitalization opportunities of national coastal fishing port economic zones that adopt the strategy of“managing fishing based on ports”；mapping out cooperation models for bluefin tuna aquaculture between China and foregin countries，accelerate the establishment of import channels for bluefin tuna fries；apply previous research results，and carry out scientific research to promote the development of bluefin tuna industry in China.