WSP12629 ‎(2)‎

• File Number: 8240.200.10.H
• Description: Upper Colorado River Endangered Fish Program
• Basin: Colorado Mainstem
• Date: 10/15/2001
• Author: Thomas P. Nesler CDOW
• Title: Stocking Plan for Endangered Colorado River Fish Species in Colorado
• Water Supply Pro - Doc Type: Publication

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Further, the following species interactions and recovery actions are assumed/anticipated:

1) Establislunent of razoIback sucker at or above the abundance criterion may cause reduction
in biomass of flannelmouth sucker due to shared use of low-velocity habitat and potential
competition.

2) Biomass and production of common carp, white sucker and other nounative species may
be reduced by control efforts, therefore reducing competitive pressure upon sympatric
native suckers, and perhaps facilitating expansion of razorback sucker numbers beyond the
target level.

3) With succel:sful establishment of an adult razorback sucker population, general abundance
of other native species and some nounative species may be reduced as a result of some
competition for available resources.

Reach priorities were based on the following considerations:

1) The Colorado River (Rifle to Debeque) and Gunnison River reaches are higher priority
, than the Palisade to Stateline reach of the Colorado River due to the higher relative
abundance of native fishes in general and native suckers in particular, and the lack of an
abundance (If large predaceous fish species; suggesting a more favorable environment for
survival.

2) Concentrations of selenium that may impact razorback sucker reproduction adversely via
survival of larvae appears to be greater in the Gunnison River reach, making the upper
Colorado River reach potentially more favorable for reintroduction, and ultimately,
successful reproduction and survival of young razorback sucker.

Stocking Plan - B1mytaiI (Table 1)

BonytaiI are considered the second highest priority for stocking, but only due to the high
value of expanding the genetic material remaining in the few, viable stocks of razorback sucker
left in the wild. Bonytail are functionally extilpated in the wild and restoration stocking of
progeny from the remaining captive stock is the only recourse for re-establishing populations. The
source for bonytail to be stocked will be from the captive broodstocks currently being held at
Wahweap State Fish Hatchery in Utah or Dexter National Fish Hatchery in New Mexico. These
fish were progeny from 10 artificially-spawned bonytail captured from Lake Mohave (Minckley
et al. 1989). No further infusion of new genetic material is anticipated due to the extreme rarity
of captures of viable bonytaiI from anywhere in the basin. Maintenance of the captive broodstock
at Dexter National Fish Hatchery has been the primary safeguard against extinction. This
approach, while realonable in the short term, reduces the probability of maintaining the full range
of heterogeneity of the remaining wild gene pool through long term selection for domestication