9554

• UCREFRP Catalog Number: 9554
• Author: Monroe, L. and T. Hedrick.
• Title: Northern Pike ‎(Esox lucius)‎ Control in the Middle Green River, Utah 2001-2006.
• USFW Year: 2008.
• USFW - Doc Type: 109,
• Copyright Material: NO

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LIST OF KEY WORDS

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Northern pike, Esox lucius, nonnative removal, cleithra, nonnative fish, middle Green River

EXECUTIVE SUMMARY

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Beginning in 2001, researchers with the Utah Division of Wildlife Resources (Division)

in Vernal, UT, began an intensive northern pike (Esox lucius) removal program in razorback

sucker (Xyrauchen texanus) critical habitat of the middle Green River. Captures of northern pike

during the Division's basin-wide surveys had increased from 1997 to 2000 and participants in the

Upper Colorado River Endangered Fish Recovery Program (Program) were concerned that large

numbers of pike would threaten recovery of native, endangered fishes in the Green River.

During this effort, crews were asked to capture and remove all northern pike encountered

and to develop a northern pike control program or methodology, which could subsequently be

evaluated for its effectiveness. They did this by utilizing multiple gear types: electrofishing, fyke

netting, and trammel netting. Catch rates were highest for all gear types in 2001 and although

catch rates varied over the course of this study, the overall trend was a gradual reduction (in both

catch rates and numbers removed) from 2001 to 2006. Catch rates in this reach were low

compared with the Yampa River.
From 2001 to 2005, researchers collected c1eithra from northern pike and counted annuli

to determine ages. Results of this analysis were grouped into young-of-year, juvenile, and adult

age classes. Northern pike removed from the middle Green River from 2001 to 2003 were

predominantly adult fish. In 2004, most fish were juvenile fish, and in 2005, pike were evenly

distributed between juvenile and adult. Only three pike were identified as young-of-year over the

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