7872

• UCREFRP Catalog Number: 7872
• Author: Bestgen, K. R., et al.
• Title: Recruitment Models For Colorado Squawfish
• USFW Year: 1997.
• USFW - Doc Type: Tools For Evaluating Relative Importance Of Natural And Managed Processes - Final Report.
• Copyright Material: NO

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and age-2 adults, and the mean and variance for total length were relatively large (Figure 4).
From mid-June to mid-July, total length of red shiners declined due to mortality of adults.
Subsequently, average size increased from late July until water temperatures declined and red
shiner growth rates slowed in fall (Figure 4).
During a simulation, daily red shiner size distributions were estimated by linear
interpolation between data-based distributions. Each time a larva encountered a red shiner, the
predator's total length was randomly drawn from the size distribution for that day. Adult red
shiners regularly attain densities greater than five individuals/m2 in Green River backwaters
(Haines and Tyus 1990). Unless otherwise noted, we used a relatively conservative density of
.three red shiners/mZ in simulations.
Temperature-Dependent Growth
Bestgen (1996) conducted experiments to describe the affects of ration and temperature
on growth rate of Colorado squawfish larvae. Results of this study were used to parameterize the
model for the effect of temperature on larval growth, and to estimate the degree of variation in
growth rate among individuals. At the beginning of a simulation each larva was assigned a
baseline growth rate drawn at random from a normal distribution with a specified mean and a
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