Balancing Conservation and Consumption: Managing Hatchery-Origin Adult Returns

The Lostine River Chinook Salmon Supplementation program began as a conservation effort in 1995 with the collection of juvenile Chinook salmon for a captive broodstock program.  A conventional supplementation program began collecting adult broodstock in 1997 and phased out the captive broodstock program in 2010.  The first priority of both supplementation programs was to increase the overall abundance of Chinook salmon returning to spawn.  Smolt production is supported by the Bonneville Power Administration (conservation objective) and by the Lower Snake River Compensation Plan (mitigation program).  The hatchery program goal is to produce a total of 250,000 smolts to return 1,647 adults.  Adult escapement (ages 4 and 5) prior to returns of hatchery-origin Chinook salmon ranged from 90 to 233 fish from 1997 to 2000.  Hatchery-origin adult returns from 2001 to 2009 bolstered Chinook salmon adult escapement starting in 2001, ranging from 422 to 2,069 fish.  Hatchery-origin adult returns have comprised from 37.2% to 80.5% of the total adult escapement and 28.6% to 79.6% of adult spawners from 2001 to 2009.  Increases in redd abundance correlated to increases in escapement but the passage of hatchery-origin fish upstream of the weir is limited by a management agreement designed to progressively limit the proportion hatchery origin spawners above the weir as escapement increases.  During years where the passage of hatchery-origin fish upstream of the weir is constrained, hatchery-origin adult returns are out-planted to under-seeded spawning habitat and made available for consumption via harvest (tribal and sport), and distribution to tribal members and state food banks.  On average 90.7 percent of the hatchery-origin returns have been utilized for natural or hatchery production, with the remaining 9.3 percent utilized for consumption.  Natural-origin return levels in 2009 resulted in 55.4 percent (n = 885) of the adult hatchery-origin returns utilized for consumption. The preseason and real-time management processes to “best” allocate returning fish disposition is complex and imprecise.  Preferred dispositions of fish frequently differ between management entities.