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<br />54t <br /> <br />Development of Augmentation Plans for Razorback <br />Sucker and Colorado Squawfish in the San Juan River <br />Fiscal Year 1997 Project Proposal <br />U.S. Fish and Wildlife Service, Region 6 <br /> <br />Background: <br /> <br />Colorado squawfish and razorback sucker, are both federally-listed endangered fish native to the <br />San Juan River. The capture of low numbers of Colorado squawfish of all life stages over the <br />past ten years has confirmed that a small, but reproducing population of Colorado squawfish still <br />exists in the San ruan. Razorback sucker were a confirmed member of the San Juan River native <br />fish fauna as late as 1988. However, intensive electrofishing surveys conducted in the San Juan <br />River from 1991 to 1996 have failed to capture any wild razorback sucker in the reach between <br />Farmington, New Mexico and Lake Powell. No larval or juvenile razorback sucker have ever <br />been scientifically documented in the San Juan River. From this data, it is assumed that the San <br />Juan River's wild razorback sucker population consists of only a few, old adult fish. <br />Consequently, an experimental stocking study for razorback sucker began in 1994. The purposes <br />of this study were to evaluate whether habitat capable of sustaining razorback sucker still exists in <br />the San Juan River, what the habitat needs of this species in the San Juan River were, and <br />determining the feasibility of using hatchery-reared fish in an artificial augmentation effort in the <br />San Juan River. At present, approximately six percent of all experimentally stocked fish have <br />been contacted either through radio telemetry or electrofishing recapture. From data obtained in <br />this study, it is apparent that stocked, hatchery-reared razorback sucker can survive in the San <br />Juan River. <br /> <br />The need for artificial propagation and augmentation of these two species in the San Juan River is <br />apparent for several reasons. The small numbers of individual Colorado squawfish found in the <br />river make using these fish to answer specific research questions problematic. There is also a <br />danger of waiting too long to artificially augment and losing the genetic diversity contained in the <br />San Juan River population to old age, angling mortality, or unforeseen catastrophe. A <br />catastrophic event could be especially devastating given the small numbers of adult Colorado <br />squawfish, and their close spatial proximity to one another in the river. Experimentally-stocked <br />adult razorback sucker appear to be doing well in the San Juan River and have provided valuable <br />data about this species in the wild. Augmentation of these two species would increase population <br />numbers, provide more individuals for research purposes, add genetic diversity to the existing <br />gene pool, and provide a riverine refugia population that would, hopefully, remain stable until <br />further research can identifY factors limiting successful recruitment of these species in a highly <br />modified river system. The San Juan River Long Range Plan identifies the need to assess the <br />feasibility of, and then implement the augmentation of razorback sucker and Colorado squawfish. <br />Development of stocking plans for these two species in the San Juan River will provide the <br />necessary guidance for augmentation efforts as well as directly fulfilling objective 5.3.8.2 of the <br />San Juan River Long Range Plan. These plans will discuss broodstock availability, potential to <br />get razorbacks from Lake Mohave, grow-out locations, and associated genetic concerns. <br /> <br />6 <br />