JOHN PRENTICE, WILFRED J. DEAN, JR., MICHAEL REED, AND EARL W. CHILTON II, Heart of the Hills Research Station, Texas Parks and Wildlife Department, HC 7, Box 62, Ingram, Texas 78025, USA

A total of one hundred-twenty-five adult triploid grass carp were surgically implanted with radio-transmitter tags and released into five Guadalupe River reservoirs in Texas. These fish were tracked to follow movement away from target areas over time and particularly during flood events. Radio tags were programmed to pulse at varying rates depending on temperature and to activate on/off cycles (4 days on and 3 days off weekly for 6 weeks followed by 5 days on and 25 days off for 5 months followed by 6 days on and 85 days off) continuing until batteries expire. After 1-year's tracking, most (109) radio frequencies are being found and nine fish have moved downstream past from one to four reservoir dams. Drought conditions, extremely low river flows and no flood events throughout the study have provided the least conducive conditions for fish movement from reservoirs.