| n this investigation, groups of diploid (control) and triploid all-female rainbow trout (Oncorhynchus mykiss) and mixed-sex (i.e., male and female) brook trout (Salvelinus fontinalis) were subjected to different lengths of acute handling/confinement stresses. In each experiment, blood samples were collected from equal numbers of diploid and triploid fish at regular predetermined intervals. In the first set of experiments, analysis of these blood samples was used to establish the time course and magnitude of the stress response. Measurement of hematocrit (% packed cell volume in blood) and plasma cortisol concentrations in all-female rainbow trout, and hematocrit and plasma cortisol, glucose, sodium, potassium and chloride concentrations in brook trout were used for the evaluation of stress response. These variables are well documented indicators of the primary and secondary stress response in fish. The effect on these variables of cohort sampling and the diurnal cycle were also analysed in diploid and triploid brook trout.;In a second set of experiments, specific hematological responses to acute stress in diploids and triploids of both species were analysed by using the measurement of hematocrit, total red blood cell and total white blood cell numbers, white blood cell/red blood cell ratios, differential leucocyte counts (lymphocytes, thrombocytes, heterocytes and 'other cells'), relative lymphocyte, thrombocyte, heterocyte and 'other cell' concentrations, and blood hemoglobin and plasma cortisol, glucose and chloride concentrations.;Except for minor differences, diploids and triploids of both species responded similarly to the acute stress, by expressing the typical primary and secondary effects generated by such a stress. No significant differences were found between diploid and triploid fish in their reactions to cohort sampling. However, the act of removing an individual from a tank caused significant changes in plasma cortisol (P... |
