Thermal resistance of pike (Esox lucius), muskellunge (E. masquinongy) and their F1 hybrid

Comparison of thermal resistances of pike, muskellunge, and their F1 hybrid indicates close similarity between the two species. There appears to be some hybrid vigour in that the hybrids tend to be more resistant to thermal stress at the average acclimation and test temperatures encountered in the experiments. The greatest difference between the hybrids and parents occurred at the lowest test temperatures. Differences between the parent species were apparent only in their response to acclimation temperature, the slope of the curve of resistance time on acclimation temperature being much steeper for muskellunge than that for pike.