| When a telemetry transmitter is attached to fish、 it is common to perform the surgery under anesthesia. The curing period between the anesthesia/surgery and the release of fish is usually set around 24 hours. However、 there have been very few studies that carefully investigated the curing period after anesthesia and surgery、 and there are many unclear points concerning the physiological effects of curing period on fish.[*]In this study、 chum salmon、 Oncorhynchus keta、 were put in a swim chamber where they could freely swim in order to determine the time between the end of anesthesia/surgery and the recovery of their swimming ability. [*]The experiments were conducted between September and December 2010、 using a total of 39 wild fish of both sexes in a swim chamber、 under five different conditions: no handling、 anesthesia only (anesthetic: FA100)、 anesthesia + surgery (making holes in the fish bodies)、 anesthesia + attachment of EMG transmitter (CEMG、 Lotek Inc.)、 and anesthesia + attachment of EMG transmitter and ECG data logger (W400L-ECG、 Little Leonard Co.). The critical swimming speed (Ucrit) was measured five times at 6-hour intervals from 1 to 30 hours after anesthesia/surgery in order to analyze the changes in their swimming ability. The flow velocity was increased by 0.175 m/s every 15 minutes. Ucrit values were calculated by measuring the time until fish got stuck into the end of the tank. [*]No significant difference was found between fish with EMG transmitters and ECG logger and the other three groups、 indicating that fish recovered their swimming ability within one hour after anesthesia/surgery. The average Ucrit value did not decrease during curing period regardless of the surgery method. The results of the present study are considered to be useful to select the release time of fish to which telemetry transmitters will be attached. |
