Effects of anaesthesia with tricaine (MS 222) on the blood composition of the splake (Salvelinus fontinalis X Salvelinus namaycush).

1. The effects of anaesthesia with tricaine (MS 222) and tagging on the blood composition were studied in 123 splakes in Northern Finland. 2. Anaesthetization with tricaine clearly influenced all blood values, except plasma enzyme activities (ASAT, ALAT and SAP). Blood haemoglobin and packed cell volume increased during anaesthesia, and the peak of PCV was reached within 15 min of anaesthesia. 3. the calculated E-MCHC values decreased during anaesthesia and tagging, suggesting swelling of the erythrocytes. The initial haematological values were regained with 3-4 hr of recovery. 4. Anaesthetization elevated the blood lactate concentration and the peak values were measured for splakes anaesthetised and tagged at 1 hr after recovery. 5. The blood glucose was rather stable until the peak was reached within 1 hr of recovery. The initial blood lactate and glucose were regained within 3 and 48 hr, respectively. 6. Repeated anaesthetization had only a slight effect on blood composition, but blood glucose elevated significantly (P less than 0.001) after 4 anaesthetizations.