Passage Distribution and Federal Columbia River Power System Survival for Steelhead Kelts Tagged Above and at Lower Granite Dam, Year 2

Abstract

Steelhead (Oncorhynchus mykiss) populations have declined throughout their range in the last century and many populations, including those of the Snake River Basin are listed under the Endangered Species Act of 1973. The reasons for their decline are many and complex, but include habitat loss and degradation, overharvesting, and dam construction. The 2008 Biological Opinion calls for an increase in the abundance of female steelhead through an increase in iteroparity (i.e., repeat spawning) and this can be realized through a combination of reconditioning and in-river survival of migrating kelts. The goal of this study is to provide the data necessary to inform fisheries managers and dam operators of Snake River kelt migration patterns, survival, and routes of dam passage. Steelhead kelts (n = 487) were captured and implanted with acoustic transmitters and passive integrated transponder (PIT)-tags at the Lower Granite Dam (LGR) Juvenile Fish Facility and at weirs located in tributaries of the Snake and Clearwater rivers upstream of LGR. Kelts were monitored as they moved downstream through the Federal Columbia River Power System (FCRPS) by 15 autonomous and 3 cabled acoustic receiver arrays. Cabled receiver arrays deployed on the dam faces allowed for three-dimensional tracking of fish as they approached the dam face and were used to determine the route of dam passage. Overall, 27.3% of the kelts tagged in this study successfully migrated to Martin Bluff (rkm 126, as measured from the mouth of the Columbia River), which is located downstream of all FCRPS dams. Within individual river reaches, survival per kilometer estimates ranged from 0.958 to 0.999; the lowest estimates were observed in the immediate forebay of FCRPS dams. Steelhead kelts tagged in this study passed over the spillway routes (spillway weirs, traditional spill bays) in greater proportions and survived at higher rates compared to the few fish passed through powerhouse routes (turbines and juvenile bypass systems). The results of this study provide information about the route of passage and subsequent survival of steelhead kelts that migrated through the Snake and Columbia rivers from LGR to Bonneville Dam in 2013. These data may be used by fisheries managers and dam operators to identify potential ways to increase the survival of kelts during their seaward migrations. Passage Times and Travel Rates Forebay residence and tailrace egress times were consistent among LGR, LGS, and LMN in 2013. Median forebay residence times were less than 2.00 hours at all dams and median tailrace egress times were approximately 0.50 hours. Median project passage time in this study ranged from 2.00 (LMN) to 3.06 (LGR) hours. Overall, passage times were lowest for fish that passed LMN. Of the kelts captured and tagged in the tributaries, those released in Fish Creek, which migrated the greatest distance through fluvial habitats, travelled fastest to Red Wolf Bridge (rkm 743; median = 88.2 vi Many people made valuable contributions to this study and deserve acknowledgment.

Post‐Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?

“…The high discharge through the spillways may have increased spillway attraction for the kelts (Schilt, 2007;Coutant and Whitney, 2000) and hence resulted in a high survival rate. High levels of spill have previously been reported to enhance migratory success of downstream migrating post-spawned salmonids (Wertheimer and Evans, 2005;Colotelo et al, 2012). Most fish first arrived at the turbine-intake racks, even though, on average, more water passed through the spill gates than through the turbines.…”

“…As of late, postspawners have received more attention from scientists and managers (e.g. Wertheimer and Evans, 2005;Calles and Greenberg, 2009;Kraabøl et al, 2009;Colotelo et al, 2012).…”

Intake Approach and Dam Passage by Downstream‐migrating Atlantic Salmon Kelts

“…At hydropower dams, reluctance to pass through as well as rapid passage via upward-opening spill gates have been observed (Arnekleiv et al, 2007;Nyqvist et al, 2016a). In general, high levels of spill have been reported to enhance migratory success of downstream-migrating salmonid kelts (Wertheimer & Evans, 2005;Colotelo et al, 2012).…”

Physiological indices of seawater readiness in postspawning steelhead kelts

“…Tagging studies conducted during the increased spill have been directed to determine more precise routes of passage and measure survival (Colotelo et al. ). These recent studies support that steelhead kelts are more likely to move downstream via surface spill routes than through juvenile bypass systems, and there is a positive relationship with flow.…”