9498

• UCREFRP Catalog Number: 9498
• Author: Nesler, T. P.
• Title: Stocking Plan for Endangered Coloraod River Fish Species.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

2

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

Background

Within the Upper Basin, stocking plans have been created for only the razorback sucker
in the Colorado/Gunnison rivers in Colorado (Burdick et aI. 1995) and in the middle Green River
in Utah (Wydoski 1996), and for the bonytail in the Green and Colorado rivers in Utah (Lentsch
et al. 1996). These plans were developed when the Recovery Program designated razorback
sucker and bonytail as priorities one and two, respectively, for propagation and stocking due to
their extremely precarious status in the wild. These plans were superseded by stocking plans for
razorback sucker, bonytail, and Colorado pikeminnow in Colorado (Nesler 1998) and for
razorback sucker and bonytail in Utah (Hudson et aI. 1999).

Within Colorado in the Colorado and Gunnison rivers, numbers of wild razorback sucker
were insufficient for collection and use in a 5x5 breeding matrix to even attempt to develop
broodstock. Additionally, the highest number of razorback sucker remaining in Colorado, located
in Etter's Pond near Palisade, Colorado, was determined to be dominated by potential siblings
from a very small number of parents, and potentially hybridized with flannelmouth sucker
(Genetics Panel, Colorado River Recovery Program, 1994). Therefore, Diating crosses between
any two individual fish from Etter's Pond were detennined to be genetically unacceptable due to
inbreeding risks. The Recovery Program approved development of a "blended stock" of
razorback to serve as the broodstock for the Colorado and Gunnison rivers. This stock was
formed using razorback sucker from the Colorado River ann of Lake Powell (4 fish), the San Juan
ann of Lake Powell (4 fish), riverine:fish from the upper Colorado River (4 fish), and Etter Pond
(3 fish). A captive spawning strategy for these fish is described in Burdick et aI. (1995) following
the Recovery Program's Genetics Management Guidelines (Williamson and Wydoski 1994).

Bonytail are represented by only one captive broodstock that is currently kept at Dexter
National Fish Hatchery in New Mexico. Some of these fish are also being held at Wahweap State
Fish Hatchery in Utah for reintroduction and broodstock development purposes. Since these fish
are the descendants from limited numbers of wild fish taken from Lake Mohave, and no more
viable adult bonytail are currently available from the wild stock remaining in Lake Mohave, these
fish represent the only genetic material left from which to base a propagation and reintroduction
program.

For Colorado pikeminnow, broodstock development was initiated in 1991, and 17 family
lots currently exist from that effort. Due to the relatively "stable" status of Colorado pikeminnow
populations in Upper Basin rivers (McAda et al. 1994, McAda et aI. 1996, Czapla 1997), and the
limitations of hatchery and rearing facilities within the Program (Wydoski 1994, Czapla 1997),
no further broodstock development has occurred within the 5 x 5 breeding matrix, nor have any
stocking plans been developed to use progeny from the existing broodstock held at Horsethief
State Wildlife Area near Grand Junction, Colorado. This broodstock is currently being held at
Dexter National Fish Hatchery as a back-up. In 1998, the Biology Committee recommended and
the Recovery Program adopted the propagation strategy for pikeminnow progeny to be acquired
for Colorado and Gunnison River stocking requirements through the capture of wild adult

.