Survival of Endangered Snake River Sockeye Salmon Smolts from Three Idaho Lakes: Relationships with Parr Size at Release, Parr Growth Rate, Smolt Size, Discharge, and Travel Time

Abstract

In 1991, Snake River sockeye salmon Oncorhynchus nerka were listed as endangered. The Sawtooth Valley Project was initiated to conserve and rebuild sockeye salmon populations that historically spawned and reared in five Sawtooth Valley lakes designated as critical habitat in central Idaho. We evaluated smolt survival of sockeye salmon that were stocked as parr into Redfish, Pettit, and Alturas lakes. Smolt travel time, residuals of Salmon River discharge and smolt travel time, and specific growth rate of parr explained 58% of the variation in smolt survival in a multiple‐regression model. Smolt survival was inversely related to smolt travel time, and travel time was negatively correlated with mean May discharge in the Salmon River at Salmon, Idaho. We were particularly interested in the relationships between smolt survival and parr size at release, smolt size at migration, and parr growth rate. Smolt survival from nursery lakes to Lower Granite Dam was negatively correlated with mean parr size at release and mean smolt size at emigration. Smaller parr and smolts survived better. Smolt survival to the dam was correlated with parr growth rates in the three lakes combined; the relationship was nonlinear. Smolt survival increased as specific growth rate increased up to 0.06% per day, but further increases in growth rate were associated with reductions in survival. Absolute growth rates of parr were negatively related to parr weight at release. Smaller individuals grew faster than larger individuals, apparently as a result of size‐dependent metabolic demand and prey availability. The relationships between smolt survival and parr size, smolt size, and parr growth rate differed among lakes. These data suggest that successful migrants must at least maintain weight during the winter preceding migration and that the stocking of smaller parr with lower metabolic demand may be preferable to stocking larger parr when forage is limited.Received November 18, 2010; accepted June 1, 2011

Putting the Red Back in Redfish Lake, 20 Years of Progress Toward Saving the Pacific Northwest's Most Endangered Salmon Population

“…Predator/prey and life history evaluations Juvenile fish growth and survival evaluations Juvenile and adult migration studies Genetics Gene rescue hatchery methodologies REFERENCE Budy et al 1995;Luecke et al 1996;Gross et al 1998;Pilati and Wurtsbaugh 2003;Sawatzky et al 2006;Selbie et al 2007Budy et al 1998Gross et al 1997;Wurtsbaugh et al 2001;Griswold et al 2003Beauchamp et al 1997Steinhart and Wurtsbaugh 1999;Massee et al 2007;Kendall et al 2010 Steinhart andPowell et al 2010Hebdon et al 2004Keefer et al 2008;Griswold, Koler, andTaki 2011 Winans et al 1996;Kozfkay et al 2008;Waples et al 2011;Kalinowski et al 2012;O'Reilly and Kozfkay 2014Schiewe et al 1997;Berejikian et al 2004;Pollard and Flagg 2004;Heindel et al 2005;Swanson et al 2008; forts, including determination of lake carrying capacity and zooplankton dynamics; fish growth, survival, and migration dynamics; genetics; alterations of barriers and improvements in fish passage; and husbandry methodologies (Box 1).…”

“…The ability to evaluate reintroduction strategies by life stage at release and location of release (e.g., receiving water) has remained a top program priority since inception. We evaluated rigorously the relative success of different reintroduction strategies to help interpret which approaches are most successful (Hebdon et al 2004;IDFG 2010;Griswold, Koler, and Taki 2011; see also Box 1).…”

The effects of environmental and biological factors on the length of Atlantic Salmon age‐1+ parr in three Maine drainages

“…The "bigger is better" paradigm is a frequently accepted assumption that has been supported for fishes broadly (Pauly 1980;Gislason et al 2010), for stream salmonids (Connor and Tiffan 2012), and specifically for juvenile Atlantic Salmon (Saloniemi et al 2004;Armstrong et al 2018). However, some populations can lack this size-survival relationship (Newton et al 2016;Gregory et al 2018) or they can exhibit decreased survival at larger sizes in habitats with little food availability (Griswold et al 2011). For Pacific salmon Oncorhynchus spp., a growth or size threshold (rather than a monotonic relationship) may be required for juvenile salmon to survive their early marine experience (Beamish and Mahnken 2001).…”

Migration and survival of Okanagan River Sockeye Salmon Oncorhynchus nerka, 2012–2019

“…This translates to an average survival rate of 87.0% per 100 km (95% CI 84.5 to 89.5%). In comparison, mean survival of Sockeye Salmon smolts from the Sawtooth Valley in Idaho has been estimated between 87.5 and 91.9% per 100 km to the uppermost Snake River hydroelectric project with fish passage (from Alturas, Pettit, and Redfish lakes to Lower Granite Dam, distances of 774, 767, and 750 km, respectively) [28]. Survival of these same populations in the mainstem Snake and Columbia rivers are more comparable (21-year average of 81.1% per 100 km) [68], though lower than Okanagan Sockeye.…”

“…These estimates (mean of 2.2%) and previous estimates of Okanagan Sockeye SARs ranging to more than 12% [Kim Hyatt, Department of Fisheries and Oceans Canada, personal communication] are high relative to other populations in the Columbia River Basin. Snake River Sockeye Salmon also traverse over 1,000 km and eight hydroelectric projects during the smolt migration, though SARs have been found to be much lower, at less than 1.0% from 2005 to 2009 [28]. Sockeye Salmon SARs from the Wenatchee River Basin-88 km and two hydroelectric projects downstream of the Okanagan River confluence-ranged from 0.02 to 2.55%, though these are likely biased low based on recent PIT-tag analyses and observations of adults obstructed at trapping facilities below the spawning grounds [31,52].…”