BACKGROUND

The Upper Willamette Chinook salmon Evolutionary Significant Unit (ESU) represents a genetically distinct group within the Columbia River Basin (NMFS 2008), even though this ESU has been influenced by hatchery releases in the Willamette River for over 100 years (ODFW 2010). When considering the ESU overall, hatchery fish currently make up approximately 85 to 95 percent adult returns on an annual basis (ODFW 2010). However, two populations within the ESU, the Clackamas and McKenzie river populations, are exceptions to this rule of hatchery fish predominance. Recent estimates of the wild component of the McKenzie River run range from 64 to 87 percent (Kenaston et al. 2009). Furthermore, both genetic and phenotypic analyses indicate that these wild McKenzie River fish more closely resemble historic stocks than other populations within ESU (NMFS 2008). Given the threatened status of this ESU, the National Marine Fisheries Service (NMFS) along with other regional fisheries managers have mandated the need to conserve the genetic integrity of the remaining wild McKenzie River fish specifically by preventing further genetic introgression of McKenzie River Hatchery genes into the naturally reproducing population. Specifically, the Willamette Project Biological Opinion (NMFS 2008) call for a reduction in the straying of McKenzie River hatchery fish to less than 10 percent of the natural population migrating upstream of Leaburg Dam.

Adult return data from Leaburg Dam indicates that hatchery fish compose a large proportion of the Chinook salmon run returning to the upper McKenzie River. Recent estimates of hatchery fish straying upstream of the McKenzie River Hatchery to Leaburg Dam have ranged from 16 to 46 percent (Kenaston et al. 2009). Thus, as part of the US Army Corps of Engineers’ (USACE) supplemental Biological Assessment (USACE 2007) and subsequent NMFS Biological Opinion (NMFS 2008), these agencies have called for the evaluation of alternative means to reducing the number of hatchery fish straying above McKenzie River Hatchery and spawning naturally in the McKenzie River.

Several alternatives to reducing the number of hatchery fish upstream of the hatchery have been discussed among Willamette Basin fishery managers, and include:
• a sorting facility at Leaburg Dam;
• a barrier weir and fish trap across McKenzie River immediately upstream of McKenzie River Hatchery;
• methods to increase attraction of hatchery fish into McKenzie River Hatchery fish trap (the subject of this study); and
• an overall reduction in hatchery production to reduce the number of hatchery adults returning to McKenzie River.

It is possible that to minimize straying below the allowable levels that a combination of management alternatives will be necessary. Furthermore, a secondary issue that is noted in the Draft McKenzie River Hatchery Genetic Management Plan (HGMP) (R2 2010), is that the McKenzie Hatchery historically has had difficulty meeting their collection target for incorporating wild spring Chinook salmon into the hatchery broodstock because so few natural fish enter the McKenzie Hatchery trap. In order to make the hatchery stocks as similar to wild stocks as possible, the Willamette Project Biological Opinion (2008) mandates the use of genetically integrated programs for the Willamette Hatchery Mitigation Program (WHMP); however, at this time there is uncertainty among regional fisheries managers as to what level wild fish should be incorporated into the McKenzie Hatchery broodstock. To thoroughly address all management needs the feasibility analysis of alternatives should consider balancing the need to attract more hatchery and wild fish to McKenzie Hatchery while minimizing the potential for handling and delay impacts to wild population overall.

The general objective of this study is to address the third bullet in the options listed (in bold) in Section 1.1: consider “methods to increase attraction of hatchery fish into McKenzie River Hatchery fish trap,” and similar considerations for the Leaburg Hatchery. Project alternatives may include physical modifications of the stream channel, hatchery attraction-water enhancement, chemical attractants, and/or other behavioral modification techniques to improve attract and homing of hatchery-origin adult Chinook into the McKenzie and Leaburg hatcheries.
The study is to be conducted with a two-phase process, as described in BPA’s RFP:

PHASE 1:  In Phase 1, the contractor will provide environmental, biologic, geomorphic, and engineering technical services to generate a reconnaissance-level report describing feasible alternatives with estimated costs (capital and annual O&M), based on best available science and information, and regional applications and experiences. Conceptual illustrations must be provided for engineering/geomorphic alternative actions.

PHASE 2:  Phase 2 is contingent on the identification of one or more alternative actions acceptable to NOAA Fisheries, ODFW, and the Action Agencies as reasonable and effective in resolving the McKenzie Hatchery spring Chinook straying issue. This phase will be initiated by written authorization from BPA without further competition, and will address