Abstract
This study developed a portable, low‐cost field respirometer for measuring oxygen consumption rates of large‐bodied fishes. The respirometer performed well in laboratory tests and was used to measure the oxygen consumption rates ( O 2 ) of bull sharks Carcharhinus leucas (mean: 249.21 ± 58.10 mg O 2 kg −1 h −1 at 27.05°C). Interspecific comparisons and assessments of oxygen degradation curves indicated that the respirometer provided reliable measurements of O 2 . This system presents a field‐based alternative to laboratory respirometers, opening opportunities for studies on species in remote localities, increasing the ability to validate physiological field studies.