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

TABLE OF CONTENTS

ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

LIST OF TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. iii

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

EXECUTIVE SUMMARY ............................................... v

INTRODUCTION ..................................................... 1

Project background ................................... . . . . . . . . . .. 1
Historical background of northern pike in the Yampa River. . . . . . . . . . . . . . .. 2

STUDY AREA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8

METHODS ......................................................... 10

Sampling protocol .............................................. 10

Fish handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11

Removal evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 13
Abundance estimation of northern pike . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14
Interactions between Northern pike and Colorado pikeminnow . . . . . . . . . . .. 15

RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16

Removal evaluation based on EL -CPUE . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16
Changes in backwater CPUE ..................................... 17
Abundance estimate of northern pike ............................... 18
Number and biomass of northern pike removed ................ . . . . . .. 18
Length frequency of northern pike . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
Density of northern pike ......................................... 21
Northern pike and Colorado pikeminnow ratios in selected backwaters,
1988-1991 and 1999-2001 ................................. 21
Northern pike predation and maximum prey length . . . . . . . . . . . . . . . . . . . .. 22
Predation attempts by northern pike on Colorado pikeminnow . . . . . . . . . . .. 23

DISCUSSION ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25

Effects of removal .............................................. 25

Northern pike and Colorado pikeminnow interactions . . . . . . . . . . . . . . . . . .. 27

CONCLUSIONS ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32

RECOMMENDATIONS ............................................... 34
LITERATURE CITED ....................................... . . . . . . . . .. 36

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