8173

• UCREFRP Catalog Number: 8173
• Author: Gido, K. B. and D. L. Propst.
• Title: Habitat Use and Association of Native and Nonnative Fish in the San Juan River, New Mexico and Utah.
• USFW Year: n.d.
• USFW - Doc Type: \
• Copyright Material: NO

species (using presence/absence), abundance was negatively
correlated. Abundance of the two juvenile catostomid species
showed the highest number of positive correlations with
nonnatives. This included positive correlations between adult

and juvenile E. promelas and juvenile Q. lutrensis. Juvenile Q.

discobolus also had a significant positive correlation with adult

and larval C. lutrensis. Juvenile C. latipinnis abundance was

negatively correlated with E. zebrinus as was the abundance of

juvenile R. osculus with Q. affinis and larval C. lutrensis. The

only significant correlation of an adult/sub-adult native species

with a nonnative was between Q. latipinnis and juvenile Q.

lutrensis.

DISCUSSION
Recent attempts by Power et al. (1995) to model the food-web
dynamics of large rivers recognized the need to investigate the
role of off-river water bodies as rearing areas for juveniles.
They also indicated the need to examine the relative importance
of seasonal life-history bottlenecks. In this study we examined
both factors. Secondary channels were shown to provide habitats
used by many larvae and juveniles of both native and nonnative
fish. There is, however, potentia1ly a juvenile competitive
bottleneck (Persson 1986, Persson and Greenberg 1990), where
resources for adult size classes may not be limited but
interspecific competition during the juvenile stage may limit
recruitment. This would seem to have the greatest effect during

14