Data for "Arctic Greenland cod (<i>Gadus ogac</i>) display marked seasonal plasticity of cardiac heat tolerance but not of chronotropic adrenergic scope for heart rate"

In contrast to the Antarctic, Arctic marine fishes also commonly experience large seasonal temperature swings. Here, we caught wild adult Greenland cod (<i>Gadus ogac</i>) in winter (sub-zero) and summer (>6°C) to determine how they seasonally adjust the temperature sensitivity and adrenergic control of their heart rate in relation to seasonal thermal habitat use.

Acoustic telemetry revealed that Greenland cod typically occupy shallow depths year-round (IQR: 3.3-7.0m), resulting in stable sub-zero body temperatures overwinter (IQR: -0.52 to -1.4°C) and warmer temperatures in summer (IQR: 3 to 5.5°C). Intrinsic (<i>f</i>_Hint) and maximum (<i>f</i>_Hmax) heart rates were assessed in anaesthetized cod during acute warming, revealing little adrenergic scope for heart rate (using sotalol or isoproterenol), except at warmer tempeatures in late winter.