Program and Abstracts(PDF)

Presentation 9
THE DEVELOPMENT OF AQUACULTURE TECHNIQUES FOR GREATER
AMBERJACK (Seriola dumerili) USING ARTIFICIALLY PRODUCED SEED :
TECHNOLOGICAL ADVANCEMENT OF THE SEED PRODUCTION
Hiroshi Hashimoto *1 , Kentaro Oda 1 , Yoshitsugu Masuda 1 , Hitoshi Imaizumi 1 , Hironori Usuki 1 ,
Takashi Iwasaki 2 , Takeshi Yamamoto 2 , Kazuhisa Hamada 2 , Kazuhisa Teruya 3 , Katsuyuki
Hamasaki 4 , and Keiichi Mushiake 2
1 Shibushi Station, National Center for Stock Enhancement, Fisheries Research Agency
2 National Research Institute of Aquaculture, Fisheries Research Agency
3
Ishigaki Tropical Station, Seikai National Fisheries Research Institute, Fisheries Research
Agency
4
Department of Marine Biosciences, Tokyo University of Marine Science and Technology
*Email: hhiroshi at affrc.go.jp
Survival rate in greater amberjack seed production in Japan has been low at 0 to 5%. One reason
suggested for this low survival rate is that appropriate feeding schedule and environmental
conditions for rearing larvae and juvenile of the greater amberjack have not been clearly defined.
In particular, sinking of larvae occurring in an earlier stage up to 20 days post hatching and
thrusting behavior resulting from growth heterogeneity between 20 and 25 days post hatching,
are the major causes of mass mortality. Overcoming these problems is important for establishing
techniques for artificial greater amberjack seed production.
To identify the factors causing mass mortality in the larval stage and to develop techniques
for improving the survival rate, we first optimized prey size 1) ,fish density 2) , photoperiod and
water temperature 3) , using small tanks (500 L). Next, we found that actively removing the oil
films from the water surface,increased the swim bladder inflation rate of larvae, resulting in
prevention of the sinking death. Furthermore, we showed that accommodating the start of
Artemia feeding to the smallest individuals could effectively harmonized larval growth, which
prevented the mortality due to the thrusting behavior. We then applied these optimum rearing
conditions determined in the small tanks to a mass production (80 kL tanks). As the results, we
succeeded in producing 110,000 artificial seeds with an average total length of 28 mm in mid-
July using fertilized eggs obtained during the regular spawning season (June), and 15,000
artificial seeds with an average total length of 23 mm at the end of January using fertilized eggs
obtained in the non-spawning season of December through the environmental control for
broodstock rearing.
The seed obtained from the broodstock spawned in December (winter offspring) grew to an
average total length of 20 cm and average weight of 100 g by the end of March (3 months post
hatching), 2.4 kg by the end of December (1 year post hatching), and reached to a market size of
3.1 kg by the end of next March (1 year and 3 months post hatching). Using the winter offspring,
3-9 months can be reduced for greater amberjack culture relative to the present commercial
operation using the summer offspring (the imported seeds obtained from natural waters), which
leads to save the aquafarming costs.
ANNOTATED BIBLIOGRAPHY OF KEY WORKS
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