Routine metabolism of larval and early juvenile lake whitefish (Coregonus clupeaformis) and cisco (C. artedi) at three temperatures

Abstract

Lake whitefish (Coregonus clupeaformis) and cisco (C. artedi) are important contributors to Great Lakes ecosystems and to commercial and sport fisheries. Therefore, there is interest in understanding mechanisms that influence survival and growth, particularly recruitment declines beginning at early life stages. Routine metabolism is an important parameter in bioenergetic models to predict larval fish growth, yet there are few estimates of routine metabolic rate (RMR) for early life stage coregonines. We measured RMR of larval (<19 mm total length, TL) and early juvenile (19–29 mm TL) lake whitefish and cisco at three temperatures (8, 10, and 12 °C) to establish whether there are general differences between the two species or more specific differences in response to different temperatures. The metabolic rates of larval cisco were significantly higher than larval lake whitefish at 8 and 10 °C, but no species-specific differences in metabolic rates were observed at the early juvenile stage. RMR was positively related to temperature for both species at both life stages, although the magnitude of the temperature-dependent response was less pronounced for early juvenile fish than it was for smaller fish. With higher metabolic rates earlier in life compared to lake whitefish, larval cisco may exhibit higher growth rates if food resources are plentiful and may experience faster swimming speeds to search for prey and escape predators when resources are limited relative to lake whitefish.