9562

• UCREFRP Catalog Number: 9562
• Author: Hawkins, J., C. Walford and T. Sorensen.
• Title: Northern Pike Management Studies in the Yampa River, Colorado, 1999-2002.
• USFW Year: 2005.
• USFW - Doc Type: 98a,
• Copyright Material: NO

. In Lily Park, removal was effective at reducing numbers of large northern pike
~ 600 mm.
. Removal was initially effective in all reaches, but was least effective in Maybell
and Juniper reaches, apparently due to the proximity of each reach to a source
of recruiting and immigrating fish.
. In Juniper and Maybell, the number of large northern pike ~ 600 mm was
apparently sustained in 2002 by recruitment of a strong cohort to that length.
. Northern pike densities were highest in concentration areas and northern pike
recolonized these areas after removal.
. Northern pike outnumbered Colorado pikeminnow in the river and in several
backwaters.
. Changes in length-frequency distributions of northern pike over time were
attributed to growth of strong cohorts and not a result of removal.
. There were strong cohorts of juvenile and small adult northern pike that
apparently entered critical habitat through Juniper, the most upstream reach in
critical habitat.
. Northern pike consumed prey that were up to 72% of their body length.
. Colorado pikeminnow were subject to northern pike predation attempts as
evidenced by attack injuries.
. Northern pike attack injuries were observed on 18% of Colorado pikeminnow and
annual injury rate increased over time.
. Northern pike preyed on other native fishes such as roundtail chub, flannelmouth
sucker, and blue head sucker.

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