8290

• UCREFRP Catalog Number: 8290
• Author: Day, K. S. and C. Crosby.
• Title: An Assessment of Young-of-the-Year Colorado Squawfish ‎(Ptychocheilus lucius)‎ Use of Backwater Habitats in the Green River, Utah.
• USFW Year: 1997.
• USFW - Doc Type: FG-33,
• Copyright Material: NO

Discriminant function analyses were used to determine if Colorado squawf
nursery habitats could be predicted by a model of habitat characteristics. A
conducted on numerous combinations of up to 42 variables. Models were develop
season of each year, for each season for all years, for each year and for all
pooled. Variables appearing consistently in discriminant models included back
depth. In spring samples, water temperature and the difference between main c
backwater temperatures also contributed to the models. Depending on the varia
the stepwise function, area, length and volume also contributed to discriminat
Although individual models for season and year explained up to 100% of the var
Colorado squawfish backwaters and those not used by Colorado squawfish, most i
many variables to be practical for field application. Some models yielded as
explanation of the variance.
Attempts were made to develop a single discriminant model which would co
separate habitats used by Colorado squawfish from those not used, and which wo
applicable across years and seasons. Variables entered in this model were sel
performance in the stepwise discriminant analyses conducted for each season an
data across years increased variability of the data set, thus weakening model
These general models described between 10% and 51% of the variability between
amount of variability accounted for depended on the degree of pooling. Likewi
accurately classify backwaters decreased as more data sets were combined for a
used to classify backwaters by Colorado squawfish use, these models had classi
rates between 0% and 35% for season by year tests. Classification error rates