7145

• UCREFRP Catalog Number: 7145
• Author: Inslee, T. D.
• Title: Spawning of Razorback Suckers
• USFW Year: 1981.
• Copyright Material: NO

events. However, we speculate that even relatively low spring flows may be
influential in preventing most juvenile centrarchids from surviving,to
adulthood in riverine habitats.
Schlosser (1985) studied flow regime effects on fish community, structure
in a second-order, warmwater stream in Illinois; his results were similar
to ours: low flows there resulted in a large increase in the numbers of
two minnow species, the striped shiner (N. chrysocephalus) and the blunt-
nose minnow (P. notatus), species with prolonged breeding seasons. He
concluded that stochastic events such as high flows strongly affect the
assemblage structure of stream fishes, and the relative influence of flow
regime varies among species and age groups within species. He concluded
that differences among species in their ability to reproduce under high
flow conditions are likely related to differences in their reproductive
behavior and reproductive physiology and in the habitat requirements of
larval,and juvenile fish.
Muth and Nesler (in press) have recently analyzed larval data collected in
the early 1980's from the Yampa River in an effort to determine if trends
observed in the Colorado River would also apply to another river system
containing a similar fish community. Their preliminary analyses are sup-
portive of ours and those of McAda and Kaeding (1989) in that abundance of
larvae of non-native minnow species was negatively correlated with magni-
tude'of spring flows.
Despite our poor understanding of the mechanisms involved, data collected
to date strongly support our current conclusion that in the upper Colorado
River high spring flows are important in enhancing production of some
native fishes including Colorado squawfish while evidently not affecting
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