Improving estimates of vital rates of endangered fishes on the San Juan River using novel applications of PIT-tag technology




The razorback sucker and the Colorado pikeminnow are federally endangered fish that were historically found in the San Juan River. Through stocking, populations of both endangered fish have improved. Endangered fish in the San Juan River are tagged prior to stocking or are captured and tagged with Passive Integrated Transponder (PIT) tags to allow researchers to track their movements and estimate survival, which are essential knowledge to facilitate recovery of these species. The recent development of mobile PIT-tag antenna systems could help to mitigate the negative impacts of traditional methods (e.g., electroshocking) to recapture these fish because it does not require physical capture of individuals. However, this system has a potential important drawback in that it detects tags and not fish, and is consequently more susceptible to reading tags that are embedded in the substrate than other methods. This means a tag that has been shed or is left from a dead fish cannot be differentiated from a live encounter, which can result in biased estimates of vital rates. The specific objectives of the project are to 1) develop and test methods to determine whether PIT-tag detections collected by a floating (mobile) antenna system are from tags in live fish or from tags embedded in the substrate and 2) determine if the additional “resights” from this method can be used to improve estimates of vital rates for these fishes.


  • U.S. Bureau of Reclamation
  • US Geological Survey – Utah Cooperative Fish and Wildlife Research Unit (in-kind)


  • Phaedra Budy, Principle Investigator, USGS – UCFWRU – Department of Watershed Sciences and the Ecology Center
  • Mary Conner, Co-Principle Investigator, USU – Department of Wildland Resources and the Ecology Center
  • Peter MacKinnon, Research Associate, USU – Department of Watershed Science
  • Mark McKinstry, Biological Scientist, U.S. Bureau of Reclamation
  • Ben Stout, M.S. Candidate, USU – Department of Watershed Science and the Ecology Center

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player