Introduction
During the fourth year of mechanical suppression of Northern Pike (NP) in Box Canyon Reservoir, crews deployed 854 nets and removed 751 northern pike between March 2 and April 28, with a final catch-per-unit-effort (CPUE) of 0.88 NP/net-night. The Kalispel Natural Resources Department and Washington Department of Fish and Wildlife collected 35 Northern Pike during the 2015 Spring Pike Index Netting (SPIN) Survey conducted May 4 through May 8. The resulting CPUE of 0.18 NP/ net-night (95% CI: ± 0.085), in sloughs and mainstem river between Riverbend and Pioneer Park Campground met the abundance target of < 1.73 NP/net-night for these sections of the reservoir. The CPUE north of Riverbend was 0.12 NP/ net-night and was below the target of < 0.50 NP/net-night (95% CI ± 0.11). There was no Phase 2 (post SPIN) mechanical suppression effort planned or implemented in 2015.
In total, 16,978 NP were removed in 3,964 overnight gillnet sets during the initial four years of suppression in Box Canyon Reservoir (5,808 NP in 2012; 6,452 NP in 2013; 3,967 NP in 2014; 751 NP in 2015. Based on 2015 SPIN results, the adult population in the core area south of Riverbend (including sloughs) was reduced by more than 98% following four years of mechanical suppression.