Temperature and predator-mediated regulation of plasma cortisol and brain gene expression in juvenile brown trout ().

Background: Temperature affects many aspects of performance in poikilotherms, including how prey respond when encountering predators. Studies of anti-predator responses in fish mainly have focused on behaviour, whereas physiological responses regulated through the hypothalamic-pituitary-interrenal axis have received little attention. We examined plasma cortisol and mRNA levels of stress-related genes in juvenile brown trout () at 3 and 8 °C in the presence and absence of a piscivorous fish (burbot, ).

Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta).

Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus, 1758).