Demographics and Monitoring of Repatriated Razorback Sucker in Lake Mohave

Authors: Allison Downey, Brian Kesner, Paul Marsh

Year: 2024

Abstract

Population monitoring of repatriated razorback sucker, Xyrauchen texanus, has spanned for more than 30 years in Lake Mohave, Arizona and Nevada. Marsh & Associates (M&A) personnel and the Bureau of Reclamation monitored this population using passive integrated transponder (PIT) tags that were implanted into fish before repatriation. Remote PIT scanning was initiated in 2010 to supplement annual monitoring data that was reliant on capture methods and has given researchers access to a unique, long-term dataset. Since 2011, over four million contacts have been recorded through the deployment of remote PIT scanning antennas, but little is known about the movement behavior of this population. Contact data have revealed two distinct spawning areas in Lake Mohave, one in the river zone and one in the basin zone. Site fidelity is readily apparent; so much so that the two groups within the lake are treated as separate subpopulations. However, there is substantial scanning data to indicate individual movement between the two subpopulations that may be driven by spawning behavior. Contact data from a group of stalwarts, individuals that are known to have survived for at least 10 years post-repatriation, were analyzed to assess the hypothesis that there is sex-specific movement behavior among razorback sucker in Lake Mohave. This valuable dataset will continue to inform management strategies for repatriated razorback sucker in Lake Mohave and contribute to the success of the population lake-wide.