Metabolic rates of minke whales (Balaenoptera acutorostrata) in cold water

Body temperature, blubber thickness and lung capacity (Vc) were recorded in newly killed minke whales, while respiratory frequency (f) was determined in free-swimming animals. Mean deep (thoracic) body temperature was 34.7 +/- 0.8 (SD) degrees C (n = 14). Weighted mean core/blubber interface temperature in animals caught in 2.5-5.5 degrees C water was 28.8 +/- 1.7 degrees C (n = 8). The minimum average rate of sensible heat loss (HLs) was 3.81 +/- 0.53 (SD) W kgw-0.75 (n = 8) in animals with body masses (w) in the range of 1840 to 5740 kg, HLs being inversely proportional to w (HLs = -2.98 10(-4) w +4.89 W kgw-0.75 (n = 8, r2 = 0.73, P less than 0.01)). The average rate of respiratory heat loss (HLr) was 0.26 +/- 0.04 (SD) W kgw-0.75, regardless of w, in the same 8 animals. Total rates of heat loss (HL = HLr+HLs) in 2.5-5.5 degrees C water ranged between 3.40 and 4.87 W kgw-0.75, with an average of 4.06 +/- 0.52 (SD) W kgw-0.75 (n = 8). Estimates of oxygen consumption based on records of f and Ve, and data on oxygen extraction from other cetaceans, yielded a range of metabolic rates which compared nicely with the calculated HL values.