7741

• UCREFRP Catalog Number: 7741
• Author: Burdick, B. D.
• Title: A Plan to Evaluate Stocking to Augment or Restore Razorback Sucker in the Upper Colorado River - Final.
• USFW Year: 1992.
• USFW - Doc Type: \
• Copyright Material: NO

D
EXECUTIVE SUMMARY
The purpose of this document is to describe an experimental stocking
program for razorback sucker in the upper Colorado River that would 1) answer
specific research questions essential for recovery, and 2) evaluate the
utility of stocking greater numbers of juvenile and adult-size, hatchery-
produced razorback sucker to achieve recovery goals. This plan is intended to
serve as a conceptual document aimed at addressing a general course of action
to be taken in an experimental stocking program.
The total catch of adult razorback sucker in the upper Colorado River and
its tributaries has declined drastically from 1974 to 1992. Recruitment of
young razorback sucker has not been documented in the upper Colorado River
over the past 28 years. Because of this, known populations in the upper
Colorado River are composed exclusively of old, adult fish. Factors related
to the endangered status of the razorback sucker and ultimately to its
recovery include habitat alterations, predation and competition by non-native
fishes, and lack of successful recruitment. If extinction of this fish is to
be prevented and populations restored, a recovery program is necessary.
This recovery strategy is part of the Recovery Implementation Program for
Endangered Fish Species in the Upper Colorado River Basin. The ultimate goal
of the recovery program is to protect, maintain, and establish naturally self-
sustaining razorback sucker populations. One of the five recovery
implementation program elements is stocking native species.
Artificial propagation and release of hatchery-reared razorback sucker is
a potentially vital component to recovery of this species. An experimental
stocking study using hatchery-reared razorback sucker may provide information
useful in understanding the ecology of wild razorback sucker while assessing
the utility of stocking in the recovery effort. Field experiments using
hatchery fish could provide information on the factors that impact the success
of wild razorback sucker. The genetic risks associated with stocking
hatchery-produced fish must be identified acknowledge an aliminatari or at
least minimized before releasing hatchery fish. The first step in developing
a stocking strategy is to identify options resulting in a minimum degree of
genetic risk and high probability of success. Future stocking will be based
on the results of this study plan, ongoing genetic studies, genetic risks
assessment, and recommendations from habitat assessment studies. If
indicated, stocking could be used to augment existing razorback sucker
populations, to restore populations in unoccupied historic habitats, and to
maintain genetic integrity and natural variation of those populations.
Wild, adult razorback sucker from the upper Colorado River have been
collected to establish broodstock and refugia; attempts are continuing to
further supplement this stock. The first priority will be to produce an F,
captiv ck using- wild fish to ensure that genetic diversity is not lost.
Progeny produced from paired matings of wild or ish will be used for
experimental stocking. Breeding strategies will define the criteria and
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