Using maximum heart rate as a rapid screening tool to determine optimum temperature for aerobic scope in Pacific salmon Oncorhynchus spp.
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
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
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.