## (3) Limits in the use of natural seeds

In the past, all seeds for aquaculture had been acquired by catching wild young fish or larvae. However, in order to acquire seeds in a stable manner, development of artificial seed production has made progress. Today, artificial seeds can be used not only for aquaculture of fish such as red sea bream, sole, tiger puffer and coho salmon, but also for aquaculture of tiger shrimp and algae such as laver.

Some fish species for which wild seeds are used in aquaculture, such as Japanese eel and Pacific bluefin tuna, are subject to calls for stricter fishery management due to deterioration and destabilization of resource conditions. Therefore, there is a challenge of using wild seeds and managing resources at the same time. To address this challenge, for bluefin tuna aquaculture, the Minister issued an instruction on reinforcement of resource management. With regard to Japanese eel, discussions were advanced toward building a resource management framework in the East Asian region as an international resource management measure, while within Japan, resource management pertaining to the catching of glass eel, fishing of parent eel, and eel aquaculture was promoted in a combined manner.

[Changes in the stocking volume and the price of glass eel]

Source: Compiled by the Fisheries Agency based on Ministry of Finance, Trade Statistics (import volume) and industry survey (stocking volume and transaction prices)

Note: The catch volume is obtained by subtracting the import volume from the stocking volume.

## [Regulation on bluefin tuna aquaculture]

Instruction of the Minister of Agriculture, Forestry and Fisheries concerning reinforcement of resource management in bluefin tuna aquaculture (issued on October 26, 2012)

The following are required from October 26, 2012 onward:

(1) no new arrangements are to be made with regard to aquaculture sites that would increase the annual stocking volume of wild seeds in each prefecture from the 2011 level; and

(2) in order to ensure that the annual stocking volume of wild seeds in each prefecture will not increase from the 2011 level as a result of expanding the size of fish pens, restrictions and conditions pertaining to the number of fish pens, etc. are to be attached to the fishery right.

$ ^{*} $ Aquaculture sites for artificial seeds are excluded from application of the instruction above.

## [Column: Current status of artificial seed development concerning tuna and Japanese eel]

O Development of the production technology for artificial seeds of bluefin tuna was started by Kinki University in the 1970s. The university succeeded in full-cycle aquaculture for the first time in the world in 2002, and established the artificial seed production technology. Further technology development has been promoted mainly by the Fisheries Research Agency toward culturing tuna onshore which is less affected by the external environment.

O Production technology for artificial seeds of Japanese eel had been studied by the University of Tokyo, Hokkaido University and other research institutes since the 1960s. The Fisheries Research Agency succeeded in full-cycle aquaculture in 2010. However, since many problems still remain for commercialization, such as the difficulty of acquiring the feed (shark eggs) and maintaining a suitable environment, further technology development has been promoted.

## (4) Improvement of aquaculture feed

At the time when fish aquaculture was only started, raw fish had been used as aquaculture feed. Later, moist pellet (MP), which is made by mixing powder feed with raw fish at the aquaculture site, was developed, achieving better nutrition and less contamination of aquaculture sites. After that, extruded pellet (EP), which is pre-molded solid compound feed, was developed, achieving better preservability, more stable nutrition and even less contamination of aquaculture sites. At present, the respective forms of feed are used according to the fish species and circumstances.

O Compound feed, which is capable of controlling the nutritional balance throughout the year, has contributed to stabilizing the quality of cultured fish.

[Mainly used feed]

Feed type	Mostly raw fish	MP	EP
Species	Bluefin tuna	Yellowtails	Red sea bream Coho salmon Sole Tiger puffer Tiger shrimp Sweetfish Carp

Source: Compiled by the Fisheries Agency based on various data