Abstract
The mean ± s.e. optimum temperature ( T opt ) for aerobic scope in juvenile coho salmon Oncorhynchus kisutch was determined to be 17·0 ± 0·7° C. The repeated measures protocol took 3 weeks to complete the T opt determination using 12 fish tested at five temperatures separated by 2° C increments. This experiment also demonstrated that the T opt was associated with maximum heart rate ( f H ) failing to maintain a Q 10 ‐related increase with temperature. When maximum f H was produced in anaesthetized fish with pharmacological stimulation and f H measured from electrocardiogram recordings during acute warming, the Arrhenius break temperature (ABT) for Q 10 discontinuities in maximum f H (mean ± s.e . = 17·1 ± 0·5° C for 15 ppm clove oil and 16·5 ± 0·2° C for 50 ppm MS‐222) was statistically indistinguishable from the T opt measured using aerobic scope. Such a determination took only 3 days rather than 3 weeks. Therefore, it is proposed that determining ABT for discontinuities in maximum f H in anaesthetized fish presents itself as a valuable, high‐throughput screening tool to assess T opt in fishes, a metric that has become recognized as being extremely valuable in fish biology and fisheries management.