Swimming respirometry provides insights into the physiological energetics of juvenile Atlantic bluefin tuna Thunnus thynnus

David J. McKenzie, John F. Steffensen, Patricia Reglero, Edurne Blanco,Vincent Kerzerho, Tristan Rouyer, Fernando de la Gándara, Aurelio Ortega,2026. Swimming respirometry provides insights into the physiological energetics of juvenile Atlantic bluefin tuna Thunnus thynnus. Journal of Experimental Biology.Volume 229.Issue 4.February. 2026. https://doi.org/10.1242/jeb.250696

Abstract: Swimming respirometry was performed on juvenile (age 0+) Atlantic bluefin tuna, mass 565±90 g (mean±s.d., n=6), to measure elements of respiratory metabolism and exercise performance. At 19°C, the mean standard metabolic rate (106±48 mg O2 h−1) maximum metabolic rate (555±51 mg O2 h−1) and absolute aerobic scope (449±83 mg O2 h−1) were lower than mass-corrected rates of adult Pacific bluefin, but considerably higher than values in other active sympatric Mediterranean fishes at similar mass and temperature. The tuna ceased swimming at a speed of 2.0±0.2 body lengths s−1 (BL s−1). Video analysis revealed that the juvenile tuna cruised spontaneously at 3.1±0.6 BL s−1 (n=8) in their rearing tank, significantly faster than achieved in the tunnel. Extrapolation of respirometry data to 3 BL s−1 estimated a routine metabolic rate for swimming of over 650 mg O2 h−1. The results indicate that juvenile Atlantic bluefin tuna are high performance animals with elevated metabolic costs for their lifestyle of ceaseless swimming.

Keywords:Atlantic bluefin tuna,Kinematics,Routine metabolic rate, Spontaneous activity,Standard metabolic rate,Swimming respirometry