Altered temperature regimes and hydrological cycles from changes in climate will dramatically impact aquatic ecological processes and freshwater fish species. Understanding how freshwater fish species respond to water temperature and stream flow changes is critical to predicting population viability under climate change scenarios. We examined seasonal effects of water temperature and stream flow on growth of brook trout (Salvelinus fontinalis) in West Brook, a 3^rd order tributary in western Massachusetts, USA.  We estimated effects of environmental variation on growth across fish age and seasons by analyzing a long-term data set of > 2500 fish using linear mixed-effect models. 

Results/Conclusions

Growth (mm·d^-1) of brook trout was highly seasonal with fastest growth occurring during spring followed by summer, and was age-specific with fastest growth for young fish. Brook trout grew the fastest in warm wet springs and faster in cool wet summers compared to warm dry summers.  Growth rates during winter were low and tended to increase with water temperature and decreased with stream flow.   Our results suggest that brook trout growth will respond to environmental variation in complex and context-specific ways, and provide the key link between environmental variation and biological response.  As such, the results will be useful for evaluating effects of future climate change scenarios on population persistence.