7216

• UCREFRP Catalog Number: 7216
• Author: McAda, C. W. and L. R. Kaeding.
• Title: Relations Between the Habitat Use of Age-0 Colorado Squawfish and Those of Other Sympatric Fishes in the Upper Colorado River Basin \
• USFW Year: 1988.
• Copyright Material: NO

Table 1. Wilks's lambda for discriminant function one of the analysis between
age-0 Colorado squawfish and six sympatric species examined. (All
values are significant at P<0.,01.)
sand speckled red fathead ~~ channel
River Gila spp, shiner dace shiner minnow catfish
Green 0.556 0.789 0.650 0.978 0.953 0.766
Colorado 0.914 0.998 0.775 0.999 0.986 0.915
2). A value of zero represents complete discrimination whereas I.0 represents
no discrimination between habitats used. Wilks's lambda exceeded 0.9 for red
shiner and fathead minnow in the Green River and for all species except
speckled dace in the Colorado River (Table 1).
The Schoener index of habitat overlap generally followed the same trend
as did Wilks's lambda. Overlap was greatest between age-0 Colorado squawfish
and red shiner, fathead minnow, sand shiner and channel catfish in both the
Green and Colorado rivers (Table 2). Red shiner and .fathead minnow showed
higher habitat overlap with Colorado squawfish in the Green River than in the
Colorado, while sand shiner showed higher overlap in the Colorado River than
in the Green. Speckled dace exhibited less habitat overlap with Colorado
squawfish than did the other species, while the Gila spp. showed the least
habitat overlap of the six species examined (Table 2). The one inconsistency
in the trend between Wi1ks's lambda and the Schoener Index was that of Gila
spp. in the Colorado River. This may have resulted from the fact that slight
shifts along the discriminant axis that represent very little true
discrimination among the variables used to describe habitat can have a great
effect on the Schoener Index.