Issues of sustainable aquacultural seedlings in Japan

The Japanese archipelago, extending from north to south, is home to a variety of ocean regions ranging from subarctic to temperate to subtropical, with complex coastlines, and is interrupted by ocean currents such as the Kuroshio Current and Oyashio Current, making it one of the world’s richest fishing ground and suitable habitat for a rich variety of fish and shellfish species. Since ancient times, the Japanese people have fished and used various types of fish and shellfish inhabiting each ocean region as food, and the current fishing industry and fish-eating culture have become well developed. In addition, in order to secure stable supplies of marine products and the sustainable development of the fishing industry, the release of young fish and the cultivation of fish, bivalves, crustaceans, and seaweeds are being conducted in many areas to maintain and increase resources. Currently, yellowtail, red seabream and scallop account for more than 50% of domestic production. Even the less abundant grouper species such as longtooth grouper and seven-band grouper, yellowtail amberjack, Japanese jack mackerel, chub mackerel, thread-sail filefish, filefish, Japanese sea perch, chicken grunt, striped beakfish, marbled rockfish etc. are also now available and highly valued in the Japanese markets. Although slightly different from aquaculture, capture-based aquaculture (short-term aquaculture) of Japanese spiny lobster, Japanese blue crab, common octopus, horned turban, Manila clam etc. has also been underway for quite some time. For sustainable development of aquaculture, it is important to secure a large and stable supply of artificial seeds rather than natural seeds. Currently, there are ongoing researches to achieve 100% artificial seedling production of yellowtail, eel and tuna, which are representative species for Japanese aquaculture. Similarly, technology to produce artificial seedlings is needed for new cultivated species. Fortunately, Japan has a number of seedling production technologies that have been developed through sea farming. Over the past 60 years, a total of 150 seedling production technologies for 73 species of fish, 23 species of crustaceans, 38 species of shellfish and 16 species of other marine seafoods have been developed so far. In recent years, new technologies such as closed recirculating aquaculture systems and LED lighting have been introduced, making it possible to produce seedlings of various fish species that were previously considered difficult to breed. In this symposium, we will introduce the technologies for producing seedlings of spotted halibut, common octopus, pen shell and hiziki, which are being researched and developed as new target species for release of seedlings and aquaculture.