9532

• UCREFRP Catalog Number: 9532
• Author: Anderson, R. and G. Stewart.
• Title: Riverine Fish Flow Investigations.
• USFW Year: 2000.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

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The species composition in the study area was not very similar to the longer reach, an

indication that the habitat in the study area may not be representative of the river in general.

In the study area bluehead composition was 12.7% in 1998 and 7.9% in 1999, but was 23.2%

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and 24.9% for 1998 and 1999, respectively for the non- study area. (Table 1). The study area

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also had a higher percent of white sucker and round tail chub than outside the study area.

Native fish comprised 66% of the total in 1998 and 61% in 1999 in the study area compared

to 73% for the non-study sites in both years.

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Percentages offish over 15 cm captured at the Duffy site (RM 105 to 110) were also

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similar between years (Table 2). Total electrofishing distance was about the same in both

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years, but was shifted upstream 0.75 km. White sucker was the most common fish caught in

both years followed closely by the white-flannel mouth cross (Table 2). White sucker, the

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white-flannel mouth and white-bluehead crosses together comprised 69% of the total catch in
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1998 and 73% of the total catch in 1999. The next most common fish was small mouth bass at

8% in 1998 and 6% in 1999 (Table 2). Flanli:elmouth sucker, bluehead sucker, catfish, pike

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and carp ranged between 6% and 2% for both years. Nonnative fish predators (pike, catfish,

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and bass) were 13% of the catch in 1998 and IS% in 1999. Native fish comprised 14% of the

total in both 1998 in 1999. Colorado pikeminnow were 1.5% of the catch in 1998 and 0.6% in

1999.

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The species composition in the study area was fairly similar to the longer fish

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sampling reach, but as was the case with the Sevens station, fewer native fish were caught

inside than outside the study site. Native fish comprised 11% of the total catch in 1998 and

10% in 1999 in the study area compared to 16% in 1998 and 16% in 1999 for the non-study

sites. This was mainly due to a reduced percentage offlannelmounth sucker inthe river

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section that was surveyed for habitat availability.

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