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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Colorado pikeminnow and streamside-spawntaking methods. The spawning objective is to make
uniquely paired matings with resulting egg lots from each pair.

Sixteen humpback chub were collected in September 1995 at Black Rocks from the
Colorado River in Colorado near the state line. None of these fish continue to survive in
captivity. The purpose of this collection was to create a refugia population to safeguard genetic
material in the event of a catastrophic loss in the Black Rocks population. No broodstock
development or reintroduction objectives have been identified for humpback chub in the Upper
Basin due to the relative stability of four existing populations in the Yampa, Desolation-Gray,
Black Rocks, Westwater and Cataract Canyon sites, as well as a relatively large fifth population
in the Colorado and Little Colorado Rivers in the Grand Canyon.

This plan is intended to describe restoration stocking needs anticipated for the listed fish
species for rivers and river reaches within the Upper Basin in the state of Colorado. Stock
numbers needed over the next seven to nine years were estimated according to the species'
abundance objectives within the draft recovery goals. With the decision to modify stocking
objectives to be in concert with draft recovery goal population abundance criteria, revision of the
existing plan in Colorado will result in a significant modification to long term fish propagation
needs and facilities needs to produce the fish required to meet these stocking objectives. The plan
will present required objectives, justification and risk assessment for each species' proposed
stocking scenario.

Stocking Objectives and Relation to Recovery Objectives

1) To restore populations of razorback sucker, bonyt.ail, and Colorado pikeminnow to
unoccupied river reaches within Colorado,
2) To augment very small populations of razorback sucker and Colorado pikeminnow in
occupied river reaches in Colorado,
3) To establish populations of these three fish species comprised of at least three adult age
groups at the recovery goal population abundance level.

The context for defining self-sustaining populations, including the abundance criterion in recovery
goals for these fish species has been covered extensively in Nesler (2000) and USFWS
(2001a,b,c,d in draft). The rationale and justification will not be reiterated here. Also, the
Recovery Program's Genetics Management Plan (Wydoski 1995, Czapla 1999) provides
guidelines for managing genetic stocks of these species and recommends genetic stock and river
reach priorities. With achievement of the three objectives above, the fundamental building blocks
for naturally-functioning and self-sustaining populations will have been created. The
establishment of stocked, adult fish populations will contribute to recovery via expanded
distribution and greater abundance of these species in presently occupied, unoccupied and isolated
habitats, and contribute to further reduction of extinction probability for these species. Presence
of these stocked populations will contribute to recovery by making it possible to identify limiting
factors pertaining to spawning, reproduction, survival, and recruitment that cannot be assessed ,

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