10. Tunas in captivity

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This chapter describes the different aspects of tunas in captivity. There are tuna ranches or farms throughout the Mediterranean Sea, Japan, Australia, and Mexico. All three bluefin tuna species are currently involved in farming operations. The collection of tuna for the farming operations in the Mediterranean area, Mexico, and Australia rely primarily on tuna caught by purse seine. The seined tuna are transferred to a tow-pen, which is approximately 45 m in diameter and 15 m deep. In Japan, Pacific bluefin tuna, Thunnus orientalis , are collected from the Shikoku and Kyushu islands by commercial fisherman, trolling small-feathered lures along the edge of the Kuroshio Current. The live tuna are held in onboard tanks with running seawater and are then transported back to the tuna farms, where they are transferred to large rectangular pens, measuring 24 by 50 m and 15 m deep. Bluefin tuna are more challenging to collect and require the use of standard rod and reel sportfishing techniques, using baited barbless hooks. Bluefin behavior differs from yellowfin in that they rarely bite on liftpole lure, which necessitates using standard rod and reel sportfishing tackle. It is found that the feeding regime of tunas is calculated according to the biomass of fishes.