| Glucocorticoid hormones maintain homeostasis through regulating multiple processes across seasonal transitions and environmental conditions. Redband trout (Oncorhynchus mykiss gairdneri) are a cold-water species that live in cool montane streams and arid desert streams. Here, we investigate environmental, seasonal, and sex differences in the stress response and its effects on size, cortisol, insulin-like growth factor 1 (IGF-1), and glucose of trout from desert and montane streams. We captured trout from streams monthly from June through October 2020. Across environments, plasma cortisol in fish peaked in August and decreased into October. Furthermore, fish from desert streams had higher in cortisol than montane fish. Trout from both environments had similar levels of IGF-1 and glucose and similar body condition. During August, males had greater cortisol concentrations than females, suggesting sex differences in physiology that enable fish to cope with sex-specific life history. This research describes how redband trout may persist in thermally stressful environments. |