Migration Timing, Growth, and Estimated Parr‐to‐Smolt Survival Rates of Wild Snake River Spring–Summer Chinook Salmon from the Salmon River Basin, Idaho, to the Lower Snake River

Abstract

Survival, growth, and juvenile migration timing are key life history traits for at‐risk salmon populations. To estimate these traits in threatened wild Snake River spring–summer Chinook salmon Oncorhynchus tshawytscha, we tagged fish as parr in 3–17 natal streams per year from 1991 to 2003. We injected passive integrated transponder tags into parr collected from streams within the Salmon River basin in Idaho. Each spring, after the previous summer's tagging, fish were detected as smolts in the juvenile fish bypass systems of lower Snake River dams. Estimated parr‐to‐smolt survival to Lower Granite Dam (excluding migration year 1992) ranged from 3% to 48% for individual populations and from 8% to 25% (yearly average = 16%) for all streams combined. From 1998 to 2004, estimated parr‐to‐smolt survival declined from 25% to 8%, in part because of parr density‐dependent effects. Overall annual average growth rates from tagging to detection at Little Goose Dam ranged from 39.7 to 43.3 mm during 2001–2004, and significant differences in growth were observed among sites and years. Growth of individuals was positively related to elapsed time between tagging and recapture and negatively related to fork length at tagging. Annual migration timing distributions for fish populations from the different streams varied highly within and between years. Timing of the 10th to 90th percentile passing Lower Granite Dam ranged from 20 to 45 d for the combined wild populations (average = 38 d). Median passage date was negatively related to autumn temperature, spring temperature, and March river flow, and was positively related to elevation of the tagging site. Baseline data generated by this project provide a foundation for understanding the biocomplexity of these populations, which is critical to effective recovery efforts for these threatened wild fish stocks.

Stock‐Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

“…This suggests that once fish leave a hatchery they initiate active migration by responding to the same environmental cues that wild fish use (e.g., temperature, flow, and photoperiod; Whalen et al 1999;Beckman et al 2000;Achord et al 2007;Sykes et al 2009). Evidence that fish released from hatcheries do not begin migrating immediately comes from comparisons of the migration rates to the river's mouth estimated for juvenile salmon tagged with CWTs and released from hatcheries with the "active" migration rates for salmon tagged with PIT tags and detected at intermediate dams (Table A. 1.2).…”

“…The Columbia River basin is ideal for this because its ecologically diverse subbasins support numerous populations of Chinook Salmon O. tshawytscha and steelhead O. mykiss (hereafter referred to collectively as "salmon") that are genetically and phenotypically distinct yet that all enter the ocean at a common location (Rich 1920;Busby et al 1996;Waples et al 2004). Although a variety of factors likely influence migration timing (Whalen et al 1999;Beckman et al 2000;Achord et al 2007;Sykes et al 2009), our fundamental hypothesis was that ocean entry timing would largely be a function of distance to the ocean, i.e., that stocks lower in the basin (closer to the ocean) would enter the ocean earlier than those farther upstream.The Columbia River also provides an opportunity to document differences between hatchery and wild salmon because of its extensive hatchery production and-in sharp contrastnumerous wild populations that receive protection under the U.S. Endangered Species Act (ESA).…”

Potential Effects of Changes in Temperature and Food Resources on Life History Trajectories of Juvenile Oncorhynchus mykiss

“…Regardless of the mechanism, changes in growth and development have been linked to changes in fish migratory behavior, especially those that undergo longdistance migrations (Jonsson and Jonsson 2009). For example, recent studies have observed a decrease in age at migration and earlier migration timing of Chinook Salmon Oncorhynchus tshawytscha in response to environmental conditions, including increased water temperature (Achord et al 2007;Crozier et al 2008a). However, these studies have been for those salmon in which most or all individuals migrate to sea.…”

Variability in migration timing of adult Pacific lamprey (Lampetra tridentata) in the Columbia River, U.S.A.

“…For example, data on stock-specific migration timing are widely used to limit harvest of at-risk salmon populations in mixed-stock fisheries (e.g., Boatright et al 2004;Parken et al 2008). Similarly, juvenile outmigration timing data are used to reduce outmigration mortality for a variety of species at dams and other passage barriers (e.g., Benstead et al 1999;Achord et al 2007). To date, however, there has been little systematic study of the factors that affect Pacific lamprey migration timing, with the exception of broad descriptions of migration seasons (e.g., Beamish 1980;Beamish and Levings 1991;Moser and Close 2003).…”