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First published online November 19, 2007
Journal of Experimental Biology 210, 4254-4261 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.005835
Temperature effects on metabolic rate of juvenile Pacific bluefin tuna Thunnus orientalis
1 Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950,
USA
2 Monterey Bay Aquarium, Monterey, CA 93940, USA
* Author for correspondence present address: Ecology and Evolutionary Biology, 321 Steinhaus Hall, University of California, Irvine, CA 92697-2525, USA (e-mail: jblank{at}uci.edu)
Accepted 19 September 2007
Pacific bluefin tuna inhabit a wide range of thermal environments across
the Pacific ocean. To examine how metabolism varies across this thermal range,
we studied the effect of ambient water temperature on metabolic rate of
juvenile Pacific bluefin tuna, Thunnus thynnus, swimming in a swim
tunnel. Rate of oxygen consumption
(
O2) was
measured at ambient temperatures of 8–25°C and swimming speeds of
0.75–1.75 body lengths (BL) s–1. Pacific
bluefin swimming at 1 BL s–1 per second exhibited a
U-shaped curve of metabolic rate vs ambient temperature, with a
thermal minimum zone between 15°C to 20°C. Minimum
O2 of
175±29 mg kg–1 h–1 was recorded at
15°C, while both cold and warm temperatures resulted in increased
metabolic rates of 331±62 mg kg–1 h–1
at 8°C and 256±19 mg kg–1 h–1 at
25°C. Tailbeat frequencies were negatively correlated with ambient
temperature. Additional experiments indicated that the increase in
O2 at low
temperature occurred only at low swimming speeds. Ambient water temperature
data from electronic tags implanted in wild fish indicate that Pacific bluefin
of similar size to the experimental fish used in the swim tunnel spend most of
their time in ambient temperatures in the metabolic thermal minimum zone.
Key words: endothermy, metabolic rate, temperature, thermoregulation, tuna
