9378

• UCREFRP Catalog Number: 9378
• Author: Nesler, T. P.
• Title: Recovery of the Colorado River Endangered Fishes
• USFW Year: 2000.
• USFW - Doc Type: Biological recovery goals and criteria for Colorado pikeminnow, Humpback chub, Razorback sucker & Bonytail.
• Copyright Material: NO

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

Introduction

Colorado offered measurable criteria and recovery objectives for the
Colorado pikeminnow, humpback chub, razorback sucker, and bony tail in river
basins in Colorado in January 1992 as a step toward a similar process for the
Upper Colorado River Basin. Thus far, the development of recovery goals has
been diffuse, with several documents addressing recovery goals in a piecemeal or
indirect manner. These include Colorado's Interim Recovery Objectives (Nesler et
al. 1992), Population Viability Analysis for Colorado Pikeminnow (Gilpin 1993),
Endangered Fish Interim Management Objectives (Lentsch et al. 1998), Colorado
Endangered Fishes Stocking Plan (Nesler 1998), and Utah Endangered Fishes
Stocking Plan (Hudson et al. 1999). To date, no document exists as guidance for
the Recovery Program that provides downlisting and delisting criteria and goals for
the four endangered fish species. This paper is offered as a proposal for what
recovery might look like for the four endangered fishes using quantifiable,
biological criteria that can be measured and estimated from field data. Other
institutional processes and products required to address the habitat security
component of recovery are not addressed here.

Approach

Recovery goals are a human artifice constructed for the purpose of defining
the status of a target species; its population demographics and ecological function,
and the environment in which the target species is self-sustaining, and can coexist
with society in a more or less modified environment. The quantification of these
recovery goals is based to the greatest extent possible on scientific and
biologically-based criteria and knowledge. Current computer-based models can
serve to demonstrate when a species' population will persist over a select period of
time. A chosen suite of population parameters such as survival, mortality, and
growth rates are varied within a chosen range of values as if affected by a dynamic
environment. Model output indicates if persistence is achieved at or above a
chosen abundance level over a chosen time period at a select level of statistical
confidence. There is no model, however, that "tells us" when recovery is achieved
because model results are also derived using untested and simplified assumptions .
about how populations of a species relate to a dynamic environment. Apart from
the requisite of "self-sustaining", which is biological in nature, other criteria that
describe recovery, e.g., distribution, number of populations and habitat protection,
are as much a process of determination by governmental agencies or recovery
program participants responsible for the management of the species as they are
estimated from biological requirements.

In 1992, Colorado's Interim Recovery Objectives described management
stocks for each of the endangered fish species as components of recovery, and
further specified a suite of population parameters that described the structure and
function of these populations. Existing values for these parameters were provided

1