WSPC05696

• File Number: 8240.300.31.A
• Description: Colorado River Threatened-Endangered Species - Recovery Program - San Juan - Project Description
• State: CO
• Basin: San Juan/Dolores
• Water Division: 5
• Date: 2/1/1995
• Author: Unknown
• Title: San Juan River Basin - Recovery Implementation Program - Long Range Plans - February 1995
• Water Supply Pro - Doc Type: Report/Study

\

I
U
[)
]
~
I.
I
[J
~
Iii
lJ

r I
w

\J"
,.

u
"
[!
'-J.
I
,

;-1
I
\ .I

OQ15J3

of management activities.

Paramount to identifying the level of recovery possible for the endangered fish
species is the characterization of the historic fish populations, including species
diversity and abundance. To gain a better understanding of the changes from
historic to current conditions, identification of the status and trends of native fish
species is necessary. Specific research activities are designed to address the
response of the current fish community to various flow regimes. Particular
emphasis will be placed upon the response of the native and non-native fish
speCies to various Navajo Reservoir releases. The life history of the endangered
fish species will be determined within practical limits. Movement and habitat use
patterns, reproductive habits, and young-of-year and juvenile distribution and
occurrence will be emphasized. Efforts will be made to determine the response of
the endangered fish species, including abundance and distribution, to flow regimes.

While efforts have been made to address fish health concerns in cultural and
refugial environments, minimal attention has been given to determining fish health
issues in wild populations. Studies of the San Juan River fish community have
documented the widespread occurrence of external physical abnormalities. Initial
results have indicated that bacterial infections. presumably due to environmental
stresses, are adversely affecting fishes. Additional studies will be conducted to
determine.the identity, extent, and causes of fish health problems in the San Juan
River.

Studies are underway to evaluate the genetic distinctiveness of San Juan River
populations of Colorado squawfish and razorback sucker. These studies will be
incorporated into any decision regarding the necessity for establishment of refugial
populations or gene banks. If deemed necessary plans will be developed and
implemented to protect the genetic resources of the endangered fish species. The
need for an augmentation effort to restore or improve the status of endangered fish
species will be determined and implemented. Currently, a captive-bred stock of
razorback sucker from the San Juan River Arm of Lake Powell is maintained in a
refugia. A portion of these fish are being used in field studies to delineate life
history attributes of the species. These data will be used to determine the
feasibility, utility, and type of augmentation necessary to assist in recovery of
razorback sucker. Similar efforts for Colorado squawfish will be considered and
evaluated. without interference with ongoing research activities on the species.

4.4. DETERMINE ROLES OF NON-NATIVE FISH SPECIES IN THE DECLINE
OF NATIVE FISH SPECIES AND IMPLEMENT CORRECTIVE ACTIONS

In the Colorado River basin, non-native fish species have been implicated in the
decline of the native fish fauna. Past and ongoing studies have indicated that
habitat alteration and concurrent or subsequent introduction and establishment of
non-native fish species result in depleted native fish populations or their

9