Factors Associated With Razorback Sucker Recruitment in a Small Southern Arizona Pond
Buenos Aires National Wildlife Refuge
September 1999-September 2001
The razorback sucker Xyrauchen texanus is an endangered species native to the Colorado River system. To aid in recovery of the species, hatchery-raised juvenile razorback suckers have been stocked in numerous ponds around the state in a put, grow and remove for restocking scenario. In the late 1980’s, juvenile razorback suckers were stocked in many stock ponds on the Buenos Aires National Wildlife Refuge. The intent was to allow the fish to grow in these ponds until they reached sufficient size to avoid predation and then remove them for restocking into historical habitat. However, subsequent efforts to recapture fish from these ponds were unsuccessful and the fish were considered to have perished. In the summer of 1997, refuge personnel observed large numbers of razorback suckers coming to the surface of Rock Tank in obvious oxygen distress. When the age structure of the fish was evaluated, there were several classes present. Razorback suckers not only survived in Rock Tank for several years but also had apparently successfully reproduced. Successful reproduction of razorback suckers is rare in atypical habitats. Rock Tank obviously supported successful reproduction of razorback suckers over several years, whereas populations in other refuge bodies of water failed or diminished. Consequently, Rock Tank must have unique characteristics that permitted the fish to spawn and recruit successfully. Information on how fish survived and reproduced in Rock Tank is very important to razorback sucker recovery. The objectives of this project are as follows: (1) to identify factors that permitted razorback suckers to survive and recruit several generations of fish in Rock Tank and (2) to produce a comprehensive razorback sucker management plan for the refuge. This information will be used to create better habitat conditions in other refuge stock tanks, which will permit fish stocking in additional bodies of water.