Radio Frequency Electronic Tags ...

NOAA Tech Memo NWFSC-7: Technological Contributions

... "Miniature radio-frequency electronic tags, which are placed in fish, provide a means for researchers to track fish movements and study their behavior. A limiting factor in the number of radio tags that can be used in a study is the number of frequencies that tag-monitoring receivers can differentiate. Attempts to increase the number of fish that could be tracked in a study by producing several pulse rates on each frequency have not succeeded in the past. Pulse rate separation problems occurred when several tags of the same frequency were in the same area. When frequencies are separate, tags with faster pulse-rate frequencies cause higher battery drain, producing differences in tag life." ...