Evaluation of augmentation as a recovery effort for Colorado pikeminnow, Ptychocheilus lucius, and razorback sucker, Xyrauchen texanus, in the San Juan River

Authors: Bobby Ray Duran, Scott Durst

Year: 2012 (xliv)

Abstract

The San Juan River is home to two federally endangered fishes, Colorado pikeminnow, Ptychocheilus lucius, and razorback sucker, Xyrauchen texanus. Altered flow regimes, habitat degradation and fragmentation, and the introduction and establishment of nonnative fishes contributed to the decline of these fishes. The San Juan River Basin Recovery Implementation Program (SJRIP) was initiated in 1992 to protect and recover populations of Colorado pikeminnow and razorback sucker in the San Juan River Basin while allowing water development projects to proceed in compliance with all applicable federal, state, and tribal laws. One management action used by the SJRIP is the augmentation of both species of endangered fishes with hatchery-reared fishes. Augmentation is intended to increase overall population numbers, provide opportunities for research (i.e., movement studies, habitat and spawning site preferences), add genetic diversity to the existing gene pool, and continue the persistence of a spawning adult population. We evaluated the success of the augmentation program by examining several factors. We looked at the number of fish stocked compared to the stocking goals and used the SJRIP’s monitoring data to examine recaptures of stocked fish, retention and site fidelity, movement patterns and the increasing number of adult Colorado pikeminnow and razorback sucker captured in recent years. Collections of larval Colorado pikeminnow and razorback sucker confirm that reproduction is occurring in the San Juan River. Analysis of recapture data suggests that hatchery-reared Colorado pikeminnow and razorback sucker can survive in the San Juan River and that stocking can contribute in the re-establishment of these two endangered fishes in the San Juan River.