Laserfiche WebLink
<br />used to bathe the gills of the fISh until a point approximately halfway through the surgery at which <br />time the gill bath was switched to fresh water. Once surgery was completed, the fish, was transferred <br />to a quiet habitat in the river where it was observed until it swam away under its own power. <br /> <br />Transmitters were inserted into the body cavity of the fish through a 2 to 3 em incision made <br />anterior and slightly dorsal to the insertion of the left pelvic fin. The transmitter was inserted toward <br />the posterior end of the abdominal cavity so it came to rest on the pelvic girdle. The incision was <br />closed with four to five sutures using 3-0 Maxon clear monofIlament polyglyconate surgical suture. <br />All radiotagged fish were marked with either a PIT tag (native species) or a Floy tag (non-native <br />species) before being released. <br /> <br />Radio trackin~. Tracking radiotagged fish was conducted from both the air and ground during <br />each field trip. An attempt was made to locate all radio tagged fish at least one time during each field <br />trip. Aerial tracking was generally conducted during the first day or one day prior to each field trip <br />using a Cessna 182RG fixed wing aircraft. The plane was equipped with two Larsen Kulrod whip <br />antennas, one attached to the underside of each wing strut. The lead from the antenna under the <br />right wing was attached to the search receiver, SR-40; the left antenna lead (pilot's side) was attached <br />to the tunable receiver, RF-40. Headphone leads from both receivers were routed through a <br />switching box that enabled the observer to switch back and forth between the audio from each <br />receiver. <br /> <br />Typically, as the plane proceeded along the river course, radiosignals were monitored using the <br />SR-40 receiver. Upon reception of a signal the RF-40 could be tuned to the appropriate frequency <br />to count pulse rates and attempt to pinpoint the fIShes location using signal strength. Locations could <br />generally be determined with sufficient resolution to locate the fish up or downstream of the structure <br />in one pass. Approximate locations relative to the diversion structure were recorded for each fISh <br />to aid in subsequently locating the fish from the ground. Aerial telemetry was generally conducted <br />at speeds of 80-120 mph at above ground elevations of 200-1000 feet. <br /> <br />Radio tracking on the river was conducted from either a 16-foot jon boat or a 17-foot ABS <br />canoe. Search areas were determined based on logistic and time considerations. An attempt was <br />made to verify the location of all radiotagged fISh contacted from the air that were in close proximity <br />to the diversion structure (within 10 miles up or downstream). Ground searching was generally <br />conducted using a SR-40 receiver and a omni-directional whip antenna. The antenna was t;llounted <br />on a 20 mm ammunition can to provide a ground plane to increase antenna efficiency. <br /> <br />Once a signal was received, the ATS programmable receiver with a Smith-Root loop antenna <br />was used to count pulse rates, determine exact frequency and pinpoint the fishes location. Locations <br />were determined by triangulations from the boat and from shore in the vicinity of the radiotagged <br />fish. Generally two to three bearings were sufficient to determine a fishes location. <br /> <br />Upon locating a fish, a brief description of habitat and behavior and its location relative to the <br />diversion structure were recorded. If the .fish was sedentary, attempts were made to force the fish <br />to move or search the area for a carcass. If the fish was actively moving no further action was taken. <br /> <br />6 <br />