Responses of esocid fishes to warming temperatures: Laboratory experimentation on species metabolic rates

In the upper St. Lawrence River, northern pike and muskellunge are at a fraction of historical abundances and chain pickerel expansion into the region is imminent. If populations establish, the potential impact on native esocids is unclear. Physiological responses of four esocid species in various thermal environments were investigated to gain understanding of energy expenditure differences among the juvenile fishes in a changing climate. There were no statistical differences in standard metabolic rates of the four species from 11 to 30 °C except at 17, 23, and 26 °C. Grass and chain pickerel had lower Q10 measures, smaller temperature coefficients, and lower bioenergetics scenario responses indicating a slight advantage over northern pike and muskellunge in the first growing season. This advantage may allow the pickerels to populate open habitat and spatially overlap with the pikes, ultimately leading to native grass pickerel population increase and extensive non-native chain pickerel population expansion.