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Acoustic transmitter and receiver performance in freshwater and estuarine environments
Citation:
POWER, J. H. AND S. L. Johnson. Acoustic transmitter and receiver performance in freshwater and estuarine environments. Presented at Annual Meeting, Oregon Chapter, American Fisheries Society, Bend, OR, February 25 - 27, 2009.
Impact/Purpose:
We report on the performance of passive acoustic receivers intended to detect the passage of 281 acoustically tagged migratory salmonids in two Oregon coastal watersheds.
Description:
We report on the performance of passive acoustic receivers intended to detect the passage of 281 acoustically tagged migratory salmonids in two Oregon coastal watersheds. We found that ambient acoustic noise can vary considerably with location, and that “sync” pulses thought to be characteristic of transmitter code emissions can also occur on a regular basis in the natural environment. We show how using transmitters with lower power output, or longer transmitter off times, can affect the detection of transmitters. Deploying multiple receivers in arrays along the migratory route helped greatly to ensure fish did not pass the array location without detection. However, we noted considerable differences among the receivers in the arrays with regard to the odds they would detect a fish + transmitter known to be in the area, but cannot distinguish whether this is a result of receiver placement or fish using preferred routes past the arrays. We present analytical methodologies that can be used during planning and implementation of a telemetry study to ensure the best possible results are achieved.