Temperature regulation in free-swimming bluefin tuna

Abstract

1. 1. Acoustic telemetry was used to monitor ambient water temperature and tissue temperature in free-swimming bluefin tuna ( Thunnus thynnus Linneaus, 1758) over periods ranging from a few hours to several days. 2. 2. Bluefin, which experienced marked changes in water temperature, showed excellent regulation of the temperature of the stomach and epaxial muscles. 3. 3. Other species, bigeye tuna ( Thunnus obesus Lowe, 1893) and dusky shark ( Carcharhinus obscurus Lesueur, 1818) did not appear to control their body temperatures. 4. 4. The bluefin does not have a fixed temperature set-point: fish taken from the same school may vary 5°C or so in their maximum muscle temperature, and on occasions the body temperatures of fish we followed were observed to change independently of water temperature.