Advances in Fish Tagging and Marking Technology

An Improved Method for Obtaining Fine-Scale Location of Radio Tags when Tracking by Boat

John D. Koehn, John H. Eiler, John A. McKenzie, William G. O’Connor


Abstract.—This study describes an improved method that decreases tracking time but increases accuracy and precision for the fine-scale location of radio tags by reducing the receiving antenna efficiency. Test tags (48–49 MHz) were hidden in a lowland river and independently located by boat tracking using both the antenna reduction method and standard triangulation techniques. The antenna reduction method was found to be faster and more accurate, locating transmitters to within 0.19 ± 0.13 m (mean ± SE) of their actual location (error range 0–1.50 m) compared to 19.53 ± 4.81 m (error range 0–70.00 m) using triangulation. This simple approach can be applied to a wide range of radio telemetry studies and avoids many of the major sources of location error associated with triangulation including minimising the distance between the transmitter and receiver and avoiding the potential need for mapping.