Trophic ecology of northern pike and their effect on conservation of westslope cutthroat trout.

North American Journal of Fisheries Management
By: , and 



Westslope Cutthroat Trout Oncorhynchus clarkii lewisi in Coeur d’Alene Lake, Idaho, have declined in recent years; predation by Northern Pike Esox lucius, a nonnative sport fish, is thought to be a causative mechanism. The goal of this study was to describe the seasonal food habits of Northern Pike and determine their influence on Westslope Cutthroat Trout in Coeur d’Alene Lake by using a bioenergetics modeling approach. Fish were sampled monthly from March 2012 to May 2013 using pulsed-DC electrofishing and experimental gillnetting in four bays. Northern Pike catch rates from electrofishing were generally low but increased slightly each season and were highest in the southern portion of the lake; catch rates from gillnetting were approximately 50% higher during the two spring sampling periods compared with the summer and fall. Seasonal growth and food habits of 695 Northern Pike (TL = 16.2–108.0 cm; weight = 24–9,628 g) were analyzed. Diets primarily consisted of kokanee O. nerka, Westslope Cutthroat Trout, and Yellow PerchPerca flavescens. Results of a bioenergetics model estimated that Westslope Cutthroat Trout represented approximately 2–30% of the biomass consumed by age-1–4 Northern Pike. Total Westslope Cutthroat Trout biomass consumed by Northern Pike (2008–2011 year-classes) across all seasons sampled was estimated to be 1,231 kg (95% CI = 723–2,396 kg), and the total number consumed was 5,641 (95% CI = 3,311–10,979). The highest occurrence of Westslope Cutthroat Trout in Northern Pike diets was observed during spring. Thus, reducing Northern Pike predation on Westslope Cutthroat Trout would be one tool worth considering for conserving Westslope Cutthroat Trout populations in Coeur d’Alene Lake.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Trophic ecology of northern pike and their effect on conservation of westslope cutthroat trout.
Series title North American Journal of Fisheries Management
DOI 10.1080/02755947.2014.970678
Volume 35
Issue 1
Year Published 2015
Language English
Publisher Taylor & Francis
Contributing office(s) Coop Res Unit Seattle
Description 20 p.
First page 158
Last page 177
Country United States
State Idaho
Other Geospatial Coeur d’Alene Lake
Online Only (Y/N) N
Additional Online Files (Y/N) N
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