Cooperative Research Units
Education, Research And Technical Assistance For Managing Our Natural Resources
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BLM: Development of methods and analyses for more accurate and precise data on endangered Colorado River fish populations and their vital rates though innovative, passive PIT tag detection approaches.


September 2015 - August 2020


The San Juan River Basin and Upper Colorado River Recovery Implementation Program (SJ and UC RIPs) were initiated in October 1992 to protect and recover populations of four federally-listed endangered fish in the Colorado River Basin. The four listed fish species are the Colorado pikeminnow, razorback sucker, humpback chub, and bonytail. Population estimates of these fishes are critical to determining the effects of management actions and ultimately lead to decisions on whether the fish can be recovered and/or delisted. However, accurately detecting fish moving through rivers and streams is difficult and costly. The overall goal of this project is to assist with developing methods and analyses techniques, using data gathered with PIT-tag antenna systems, to improve survival, population, and movement models on endangered fish species in the Colorado River Basin. Mobile PIT tag antenna systems (e.g., on a floating raft) have recently been developed in an attempt to increase detection rates, and concomitantly, precision of vital rate and abundance estimates. Analytical methods for estimating survival and abundance are well established for standard mark-recapture studies. However, mobile systems, while promising, present new challenges to estimation techniques because tags are detected, not necessarily fish; shed tags or dead fish with tags, known as “ghost tags”, can be detected and falsely attributed to live fish. Ghost tag detection creates a bias that results in over-estimation of survival rates and abundance. We will develop a field and analytical method to classify PIT data as live fish or ghost tags when mobile antenna are used to collect data. Remote and portable PIT antennas generate large amounts of data on endangered fish survival, movement and distribution. To date, this data has not been compiled or evaluated for its analytical applications, and therefore is currently of limited use in endangered fish recovery. We will compile and analyze that data to estimate critical vital rates for these fishes and to determine the contribution of passive PIA data to those estimates. More accurate and precise data on fish populations and their vital rates will facilitate documentation of progress toward recovery through better-informed informed stocking goals and management activities.


Current Staff

Federal Staff: 101

Masters Students: 239

Phd Students: 154

Post Docs: 55

University Staff: 241

5 Year Summary

Students graduated: 695

Scientific Publications: 1962

Presentations: 4417



Funding Agencies

  • USDOI Bureau of Reclamation


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey