7989

• UCREFRP Catalog Number: 7989
• Author: Crowl, T. A. and N. W. Bouwes.
• Title: Modeling Population Dynamics of Colorado Squawfish, Razorback Sucker, and Humpback Chub
• USFW Year: 1997.
• USFW - Doc Type: for Management Objective Development.
• Copyright Material: NO

MODEL DEVELOPMENT
9riginal Model Development
We have generated a generalized, compartmentalized life-history model for Colorado
River Fishes. The original model (Appendix I) was written in using the Mathcad
software package as a stochastic population model based on the logistic growth model
(refs here). 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,, Green R., Colorado R.) include:
the number of eggs and larvae, young-of--the-year, age 1, age 2, age 3 and adult (>4
yrs old) fish per river section. Important parameters included are: reproductive effort,
both in terms of numbers of young and where spawning occurs, downstream drift
dynamics of YOY fish determined by carrying capacity, mortality estimates with inter-
annual variation for each age class (listed above); and estimates of carrying capacities
for each age class within each river segment, and sex ratios of mature adults.
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