9694

• UCREFRP Catalog Number: 9694
• Author: Hawkins, J., C. Walford, and A. Hill
• Title: Smallmouth bass control in the middle Yampa River, 2003-2007.
• USFW Year: 2009
• USFW - Doc Type: Contribution 154 Larval Fish Laboratory, Colorado State University.
• Copyright Material: NO

electrofishing and 3,569 (462 kg) of those fish were adults (Table 5). The number of
smallmouth bass removed at Lily Park was only 26% less than the number removed
from Little Yampa Canyon, a reach almost five times larger than Lily Park. We
removed the most adults (n = 1,024) in 2007 and the most sub-adults (n = 1,065) in
2005 (Table 5). Removal rates at Lily Park were similar to those observed at Little
Yampa Canyon and ranged 40-83% with the highest occurring in 2007 (Table 4).
Recapture rates at Lily Park were lower than removal rate and in every year they were
lower than those observed in Little Yampa Canyon (Table 4).

At Lily Park, smallmouth bass ranged from 22 to 510 mm, average length of adult bass
was 206 mm (SO = 45), 66-mm shorter than the average length at Little Yampa Canyon
and their average weight was 188 grams. Large adults (~250 mm) were much less
common at Lily Park than they were at Little Yampa Canyon and comprised 6 to 16% of
the smallmouth bass community each year (Figure 5).

Of the small mouth bass removed from Lily Park, 1,600 (247 kg) were translocated. As
with Little Yampa Canyon, the number of smallmouth bass translocated was highest in
2004 (n = 1,285) when fish of all sizes were translocated; in other years, the number of
bass translocated ranged from 67 to 167 fish per year (Table 5). Starting in 2004, the
number of smallmouth bass translocated each year from Lily Park was much lower than
the number translocated from Little Yampa Canyon primarily because there were few
adult bass over the acceptable 250 mm length at Lily Park (Table 5). We removed five
other nonnative species from Lily Park, including 36 black crappie, 22 bluegill, four
black bullhead, seven green sunfish, and five walleye (Table 7). We also removed
northern pike which were reported in Martin and Wright (2008). These species were
much less common than they were at Little Yampa Canyon.

Fish captured with electric seine - We removed 18,166 small, mostly young-of-year
smallmouth bass with a biomass of 126.5 kg from the lower 12 miles of Little Yampa
Canyon with an electric seine in July and August from 2005 through 2007 (Table 8).

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