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Summary of 2014 Northern Pike Suppression Results on Box Canyon Reservoir, Pend Oreille River, WA.

Category: Aquatic Invasive Species

Date Published: July 2014

Number of Pages: 5

Author(s): Kalispel Natural Resources and Washington Department of Fish and Wildlife

INTRODUCTION:

During the third year of mechanical suppression of northern pike (NP) in Box Canyon Reservoir crews deployed 861 nets and removed 3,976 northern pike. The Kalispel Natural Resources Department and Washington Department of Fish and Wildlife sampled 98 northern pike in the 2014 Spring Pike Index Netting (SPIN) Survey. This resulted in a catch per unit effort (CPUE) of 0.35 NP/ net-night (95% CI: 0.26 to 0.43), in sloughs and mainstem river between Riverbend and Pioneer Park Campground, which met the target of . 1.73 NP/net-night for these sections of the reservoir. The CPUE north of Riverbend was 0.68 NP/ net-night and was higher than the target of < 0.50 NP/net-night but fell within the 95% CI (0.34 to 1.01) which prevented initiation of Phase 2 of the mechanical suppression effort.

In the initial year (2012) of mechanical removal crews deployed 1,031 nets and removed 5,808 northern pike between March 19 and June 13. The 2012 SPIN survey took place between April 23 and April 26 with 60 nets deployed and 131 northern pike sampled. This resulted in a CPUE of 2.30 NP/net-night for all sloughs and the mainstem river south of Riverbend and CPUE of 0.80 NP/net-night for the mainstem river north of Riverbend.

The second year of mechanical suppression crews deployed 1,207 nets and removed 6,452 northern pike between March 5 and June 13 with a CPUE of 5.35 NP/ net-night. The 2013 SPIN Survey occurred from May 6 to May 9 and 410 northern pike were sampled. The resulting CPUE of 1.21 NP/ net-night (95% CI: 0.87-1.56), in sloughs and mainstem river between Riverbend and Pioneer Park Campground met the target for these sections of the reservoir while the CPUE north of Riverbend was higher than the target of < 0.50 NP/net-night (1.44 NP/ net-night) and triggered Phase 2 of the mechanical suppression effort.