Developing a method to carry one-year-old Pacific bluefin tuna Thunnus orientalis to land-based tanks

We examined two methods for carrying 1-year-old Pacific bluefin tuna (PBT), Thunnus orientalis, which have a low tolerance to skin injury, from a live-fish-transport vessel to land-based tanks. The methods involved using either a carrying-tank made of a canvas sheet or a polyvinyl chloride tarpaulin stretcher. After carrying the PBTs to land-based tanks, they were reared there for 21 days and the survival rates investigated. The survival rates were higher for PBTs carried by stretchers than by carrying-tanks. High mortalities were observed within 5 days of transport, and major parts of dead PBTs carried by the carrying-tanks had severe skin abrasions due to abnormal swimming behaviors. It was difficult to compare the two methods because of the difference between the experimental conditions, such as water temperature and apparatus material. However, the tarpaulin stretcher was more suitable to carry 1-year-old PBTs than the carrying-tank in terms of reduced cost and energy demand.