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Last modified
7/14/2009 5:02:35 PM
Creation date
5/22/2009 4:53:39 PM
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UCREFRP
UCREFRP Catalog Number
9378
Author
Nesler, T. P.
Title
Recovery of the Colorado River Endangered Fishes
USFW Year
2000.
USFW - Doc Type
Biological recovery goals and criteria for Colorado pikeminnow, Humpback chub, Razorback sucker & Bonytail.
Copyright Material
NO
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<br />38 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />,I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Bony tail <br /> <br />Status and Trend This species is functionally extinct in the wild, and is <br />represented almost entirely by captive brood stock held at Dexter National Fish <br />Hatchery in New Mexico and Wahweap State Hatchery in Utah. It is clear that <br />recovery of the bonytail from its current federal status as endangered will require <br />restoration stocking to develop adult populations and mitigation of existing threats <br />to enable reproductive success and self-sustaining natural recruitment. Available <br />historic data were inadequate to provide a specific assessment of population <br />abundance, trends, recruitment and size structure similar to the Colorado <br />pikeminnow and humpback chub. <br /> <br />Recovery Goals and Criteria No recovery goals were set for this species in <br />the recovery plan (USFWS (1990) other than to prevent the immediate extinction <br />of the species. This goal was addressed with the development and maintenance <br />of a captive population at Dexter National Fish Hatchery. The recovery plan <br />further stated that quantitative goals for down listing and delisting would be <br />addressed after information regarding factors limiting survival is obtained. Hudson <br />et al. (1999) indicates bonytail have been stocked in two locations in Utah since <br />1996, presumably the Lower Green River and the Moab Canyon-Professor Valley <br />reach of the Colorado River. No published information on the status or limiting <br />factors to survival of these stocked fish is available. The only directions on <br />potential recovery criteria have come from Utah and Colorado's stocking plans for <br />bonytail (Nesler 1998, Hudson et al. 1999, Lentsch et al. 1996). In effect, these <br />plans recommend four river reaches to initiate development of bony tail populations <br />via restoration stocking. <br /> <br />It should be kept in mind that this species is represented by a captive stock. <br />There are no known viable populations remaining in the wild. The true historical <br />distribution of this species is unknown (Lentsch et al. 1996). The captive stock is <br />comprised of progeny founded from 10 artificially spawned adults captured from <br />Lake Mojave (Minckley et al. 1989), and represents the only genetic material <br />remaining. The wild gene pool contained within this captive stock has been further <br />modified through selection for survival and domestication since 1989 when the last <br />of captive brood stock was collected from Lake Mojave (Wydoski 1995). The <br />ability to recover the bonytail relies on the successful establishment of adult <br />populations in the wild via the restoration stocking plans. The outcome of these <br />efforts is uncertain; therefore, it must be recognized that any recovery goals <br />proposed for this species would be subject to potentially significant revision based <br />on new information resulting from reintroduction efforts. The recovery goals and <br />criteria proposed here are purposefully simple for that reason. <br /> <br />Self-sustaining populations in two of the four river reaches are proposed <br />here as necessary for downlisting, and three are necessary for delisting (Table 7- <br />8). Recognizing the restricted genome from which the captive stock was founded, <br />
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