9509

• UCREFRP Catalog Number: 9509
• Author: Hill, C. G.
• Title: Dynamics of Northern Pike Spawning and Nursery Habitat in the Yampa River, Colorado.
• USFW Year: 2004.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

habitats, with the majority of samples being low or zero and one isolated case of a larger
CPUE (Figure 5). Backwater habitats in 2003 consistently had a low CPUE during all
three sampling periods, while the pond habitat had a large CPUE during the first two
periods and a decreased CPUE during the third period. This change in CPUE during the
third period may be due to age-O pike evading the electro fishing equipment as they grew
larger. The largest total catch ofage-O pike came from the gravel pit pond outlet during
2003 when on a single sampling occasion 44 age-O pike were found. In addition,
numerous age-O northern pike were observed around the gravel pit pond margins
suggesting that this area and associated habitat was well suited for pike recruitment.
Overall, no age-O pike were collected in 18 of the 37 backwaters sampled, and 32 of the
37 backwaters sampled resulted in a CPUE ofless than 3.

Evaluation of Barriers
The barrier installed at river mile 197.8 during the fall did not withstand winter
ice conditions and was repaired immediately after ice-out in March of2003. No northern
pike were visually observed behind the barrier at this time. The repaired barrier appeared
to function well and before it was removed on May 15, 2003, an overnight gill net set
behind the barrier failed to catch any northern pike.

Although the barrier installed in the spawning area adjacent to the gravel pit pond
at river mile 197 was not damaged over the winter, the barrier did not function as
expected. Water entering the back end of the area carried considerable organic debris
that was deposited on the face of the barrier, creating a dam. Water pressure from the
raised water level behind the barrier dislodged sandbags holding the barrier fencing to the
bottom.

The barrier installed at river mile 152.5 shortly before ice-out was able to
withstand the ice break up. However, it was not effective because of muskrat disruption
of the barrier. We believe muskrats burrowed under the barrier, causing the sandbags to
slide out of place and opening the seal between the barrier fencing and the backwater
bottom. Steel rebar posts inserted in front of the sandbags and through the underlying
fencing stopped the sandbags from moving out of place and no further problems were
observed.

The landowner questionnaire was sent to 169 property owners along the Yampa
River and 83 responses were received. Fifty-six percent of the respondents said they
would allow a barrier on their property, 23% said maybe and would like more
information, and 20% said no.

Discussion

Assessment of spawning and nursery habitat characteristics
During the winter, backwaters were either dry, frozen solid or had narrow
unfrozen sections with low oxygen levels, probably from decaying vegetation. It is
unlikely that northern pike inhabit backwaters during the winter for these reasons and

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