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Open-File Report 2012–1001

Prepared in cooperation with the Bureau of Reclamation

Detection Probability of an In-Stream Passive Integrated Transponder (PIT) Tag Detection System for Juvenile Salmonids in the Klamath River, Northern California, 2011

By John W. Beeman and Brian Hayes, U.S. Geological Survey; and Katrina Wright, U.S. Fish and Wildlife Service

Thumbnail of and link to report PDF (1 MB)Abstract

A series of in-stream passive integrated transponder (PIT) detection antennas installed across the Klamath River in August 2010 were tested using tagged fish in the summer of 2011. Six pass-by antennas were constructed and anchored to the bottom of the Klamath River at a site between the Shasta and Scott Rivers. Two of the six antennas malfunctioned during the spring of 2011 and two pass-through antennas were installed near the opposite shoreline prior to system testing. The detection probability of the PIT tag detection system was evaluated using yearling coho salmon implanted with a PIT tag and a radio transmitter and then released into the Klamath River slightly downstream of Iron Gate Dam. Cormack-Jolly-Seber capture-recapture methods were used to estimate the detection probability of the PIT tag detection system based on detections of PIT tags there and detections of radio transmitters at radio-telemetry detection systems downstream. One of the 43 PIT- and radio-tagged fish released was detected by the PIT tag detection system and 23 were detected by the radio-telemetry detection systems. The estimated detection probability of the PIT tag detection system was 0.043 (standard error 0.042). Eight PIT-tagged fish from other studies also were detected. Detections at the PIT tag detection system were at the two pass-through antennas and the pass-by antenna adjacent to them. Above average river discharge likely was a factor in the low detection probability of the PIT tag detection system. High discharges dislodged two power cables leaving 12 meters of the river width unsampled for PIT detections and resulted in water depths greater than the read distance of the antennas, which allowed fish to pass over much of the system with little chance of being detected. Improvements in detection probability may be expected under river discharge conditions where water depth over the antennas is within maximum read distance of the antennas. Improvements also may be expected if additional arrays of antennas are used.

First posted January 5, 2012

For additional information contact:
Director, Western Fisheries Research Center
U.S. Geological Survey
6505 NE 65th Street
Seattle, Washington 98115

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Suggested citation:

Beeman, J.W., Hayes, B., and Wright, K., 2012, Detection probability of an in-stream passive integrated transponder (PIT) tag detection system for juvenile salmonids in the Klamath River, northern California, 2011: U.S. Geological Survey Open-File Report 2012-1001, 14 p.




Description of Study Area


Detection Probabilities



References Cited

Appendix 1. Detections of PIT Tags from Other Studies

Appendix 2. Capture Histories of PIT- and Radio-Tagged Yearling Coho Salmon from Iron Gate Hatchery Used to Evaluate a PIT Detection System in the Klamath River, 2011

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