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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The basic model structure is:
Nom, =Nr+R-M+1-E
for each river section where: Nt is the number of individuals of a given age at a
specific time, R is the recruitment from the previous age class, M is the number of
individuals that die for that age class, 1 is immigration from the upstream section for the
age class, and E is emigration out of the section for that age class above carrying
capacity.
1. The sequence begins with spawning adults (initial population) occurring at
designated spawning areas. The number of spawning adults is equal to the sum of all
adults for all sections above and below the spawning area within the subpopulation
boundaries (e.g., Middle Green, Lower Green, and Colorado River for Colorado
squawfish). After spawning, the adults move back to the reach from which they
originated, to the adult habitat reaches identified and assess the number of fish already
present relative to the carrying capacity for adults. If the number of adults already
present equals carrying capacity, then the adults continue to the next available adult
habitat section. If the carrying capacity is not exceeded, then all adults remains in their
original habitat section. For each habitat segment that the adults move through from
the spawning bed, a proportion can die based upon an adult mortality rate for dispersal.
The model is set for zero mortality due to movement at this time.
2. The adults in the spawning beds produce a number of eggs per female (set by a
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