8055 ‎(2)‎

• UCREFRP Catalog Number: 8055
• Author: Crowl, T. A. and N. W. Bouwes.
• Title: A Population Model for Four Endangered Colorado River Fishes - Final Report.
• USFW Year: 1998.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

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MODEL DEVELOPMENT
Original Model Development
We developed a generalized, compartmentalized life-history model for Colorado River
fishes. The original model (Appendix I) was written using the Mathcad software
package as a stochastic population model based on the logistic growth model (Seitz
1991, Schonewald-Cox and Buechner 1991). The model is spatially explicit to allow
the exploration of subpopulation dynamics using geomorphic units as the spatial units
(Table 1). The model is also age-specific to identify potentially limiting life stages.
Important input variables for geomorphically distinct river sections (e.g., Yampa R.,
adult (>4 yrs old) fish per river section. Important parameters included are:
Green R., Colorado R.) include: the number of eggs and larvae, YOY, age 1, 2, 3, and
reproductive effort, both in terms of numbers of young and where spawning occurs,
downstream drift dynamics of YOY fish mortality estimates with inter-annual variation
for each age class (listed above}, estimates of carrying capacities for each age class
within each river segment, and sex ratios of mature adults.
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