TECHNIQUE OF ULTRASONIC TELEMETRY FOR CHINESE STURGEON, ACIPENSER SINENSIS, IN YANGTZE RIVER

The ultrasonic telemetry system consisted of a sonic receiver, a hydrophone and sonic transmitters (tags), all of which were made by Sonotronics, Inc., USA. Ultrasonic tags (two types: 78kHz and 40kHz) were tested in the Yichang reach below Gezhouba Dam and found that the sonic signal could be detected an estimated 1500m range. The receiver hydrophone system was mounted on a glassfiber boat (6.3 meter long, 63.4 kW outboard motor), using triangulation, enabled accurate locating of fish with GPS assistance. Tagged individuals could be identified by the signals from the sonic coded tags. 15 of final sexual mature sturgeon were tagged below Gezhouba Dam at the Yichang reach of Yangtze River in October 1995 and 1996. The scanned area was from the dam to the reach at Yidu City, covering about 50 km in length. All of 10 fish tagged were located in 1996, and monitored their movements of each fish during their pre spawning, post spawning and spawning. The reach was surveyed 4 times each day. 10 of the tagged fish were located totally 573 times. Each of them was successively located for 6～48 days respectively, averaging 19.8 days. The telemetry technique used in Yangtze River could be used to studies on migration, locating breeding sites and spawning requirements of other fishes or aquatic animals in the Yangtze and other rivers.