Anesthesia, fasting tolerance, and nutrient requirement of juvenile northern bluefin tuna [Thunnus orientalis]
2005
Takii, K. (Kinki Univ., Nachikatsuura, Wakayama (Japan). Fisheries Lab.) | Hosokawa, H. | Shimeno, S. | Ukawa, M. | Kotani, A. | Yamada, Y.
The present study aimed to investigate a suitable anesthesia protocol for nutritional studies, fasting tolerance, and nutrient requirements for maintenance in juvenile northern bluefin tuna Thunnus orientals weighing 0.8-0.9 g. The fish grew in a mass seedling production under completely controlled aquaculture. The solution of 0.2 mL 2-phenoxyethanol/L prepared by filtered seawater has been notably estimated as a anesthesia protocol for the juvenile, due to a shorter mean time necessary for anesthesia and recovery and higher survival rate at 24 h after recovery. All other anesthetics, 0.1 and 0.3 mL 2-phenoxyethanol/L, 0.05, 0.1 and 0.2 mL 4-allyl-2-methoxyphenol/L, and cool water temperature shocks at 16.8,12.6 and 10.4 deg C, were inferior. In a 5-day tolerance test, the juvenile was fed sand lance Ammodytes personatus through the rearing period or fasted for 2, 3, 4 and 5 consecutive days. Survival rates were about 80 or 60, 50, 10 and 0%, respectively. From the relationships between days fasting and energetic and nutritional retentions, juvenile tuna require about 142.7 kJ, 5.46 g protein and 0.44 g fat/kg body weight a day for maintenance, indicating remarkably higher requirements than other aquaculture fish.
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