EXPERT TOPIC AMBERJACK
AMBERJACK
EXPERT TOPIC Japanese Amberjack
By Matthew Holmes, Features editor, International Aquafeed
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mberjack farming in Japan began at the Ado pond in Shikoku 90 years ago. After peaking in the late 1990s the level of production has now levelled off and continues to maintain itself at a steady level. Commercial Japanese amberjack culture occurs, primarily, in nylon netting alongside the occasional use of metal sea cages. Net-pens are the most common tools used, as their steel frames facilitate harvesting in a much more efficient manner. A cheaper alternative is also the non-steel net-pen, an appliance which is inexpensive whilst also proving strong enough to withstand severe tides and typhoons. Harvesting operations through this method can, however, be challenging and arduous. The size and number of cages used in farming varies, depending upon the size of the operation and environmental conditions. A relatively small-scale production site may have five cages of 10 x 10 x 8m, while a relatively larger production site may often have over 20 cages of 18 x 22 x 8m or 12 x 12 x 12m. Even larger pens, up to 50 x 50 x 50m are in use, particularly, to grow larger-sized amberjack. As net-pen culture has developed over the past few decades, increasingly larger pens are now used, and the frames have transformed from simple wood to metal and often reinforced plastics. Larger net-pens are now desirable to produce highquality meat with the correct fat levels. Wild Japanese amberjack juveniles are reared in 5x5x5m net-pens and are sold to growers when the fish have grown to between 50-100g.
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