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<br />~. <br /> <br />Transmitters were taped to a wire harness with electrician's tape, which in turn was <br />bracketed by two plastic cable ties. This saddle was secured around the fish's caudal <br />peduncle, a process that took approximately 30 sec. Fish were held overnight and <br />released the following morning. We believe this may be the first lirn~ lhis It:c1Ulique has <br />been used on freshwater fishes. <br /> <br /> <br />Photo 1. External attachment technique used <br />to attach sonic transmitters to adult bonytail. <br /> <br />Fish movements were monitored using a directional hydrophone equipped with a <br />magnetic compass. Locations were ascertained from bearings taken from two fixed <br />stations. One monitoring location was apoint located on the northern end of the river <br />levee and the second was on the northern end ofthe high levee; the latter point was <br />accessed by boat. <br /> <br />Following release, study fish immediately sought refuge inside rock interspaces of the <br />high levee. Locations were determined using an omni directional hydrophone attached to <br />a 2.2-m pole that could be slid in large cracks between rocks. The high levee shoreline <br />was divided into 26, IS-m linear zones (A-Z), so fish location within the levee would be <br />consistently identified (Map 1). <br /> <br />We had initially planned to conduct hourly, 24-hour monitoring, however, there were no <br />day-time occurrences of fish in open water and it became obvious that fish were only <br />moving at night. The majority of the monitoring effort therefore focused when fish were <br />active. <br /> <br />Monitoring continued for 8 weeks, starting each Monday and concluding after dawn <br />Thursday. Monitoring began by locating all study fish before sunset. Both monitoring <br />stations were manned at sunset and directional bearings of fish signals were taken from <br /> <br />4 <br />