Hydrosystem, Dam, and Reservoir Passage Rates of Adult Chinook Salmon and Steelhead in the Columbia and Snake Rivers

Abstract

We assessed upstream migration rates of more than 12,000 radio-tagged adult Chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss past a series of dams and reservoirs on the Columbia and Snake rivers. Most fish passed each dam in less than 2 d. Migration behavior in reservoirs and through multiple dam-reservoir reaches varied within and between years and between species. Within years, spring-summer Chinook salmon migrated more rapidly as water temperature and date of migration increased; between years, spring-summer Chinook salmon migrated fastest in low-discharge years. Steelhead migrations slowed dramatically when summer water temperatures peaked within each year, then increased as rivers cooled in fall. Mean summer temperatures explained more between-year variation in steelhead passage rates than did differences in discharge. Fall Chinook salmon migration rates also slowed during periods of warm water. Protracted passage times within the hydrosystem were most likely for fish from all runs that fell back over and reascended dams and for steelhead that sought thermal refugia by straying temporarily into coldwater tributaries.

Behavioral Thermoregulation and Slowed Migration by Adult Fall Chinook Salmon in Response to High Columbia River Water Temperatures

“…The imperative of reaching spawning grounds at appropriate times may have prompted adult salmon to continue migration even when temperature conditions were suboptimal. This behavior contrasts with that from similar analyses for adult steelhead O. mykiss, where we found stronger relationships between temperature, passage rates, and the proportions of radio-tagged fish that temporarily entered lower river tributaries (Keefer et al 2004a;High et al, in press). Associations between water temperature and salmonid distributions and behaviors have been relatively well-studied because of the species' commercial, recreational, and ecological importance.…”

“…And although some stocks, particularly steelhead, have some flexibility with which to react to prevailing river flow and temperature conditions (Robards and Quinn 2002;Keefer et al 2004a), flexibility in migration timing generally appears to be limited for salmonids. Quinn and Adams (1996) observed that return timing for Columbia River sockeye salmon was less variable over time than for nonindigenous American shad Alosa sapidissima, and suggested that migration timing for sockeye salmon was less plastic than for the introduced species and did not match the rate of environmental change.…”

“…Because we expected salmon to avoid high water temperatures when possible, we predicted that more recent fall runs would arrive either earlier or later than the long-term average in response to warming of the lower Columbia River. Earlier timing might be expected for some fish because migration rates are higher at moderately warmer temperatures (Keefer et al 2004a), while later timing may occur if fish delay or stop migration in response to high temperatures. Second, we hoped to identify where and how fish responded to high water temperatures and to quantify resulting migration behavior.…”

Experimental evaluation of fishway modifications on the passage behaviour of adult Chinook salmon and steelhead at Lower Granite Dam, Snake River, USA

“…Further, the proportion sampled each day varied slightly, and we did not sample at night because few adult salmon and steelhead pass dams at night (Robards and Quinn, 2002;Keefer et al, 2004b;Naughton et al, 2005). During the 2-year study transmitters were placed in 3355 Chinook salmon and steelhead in 2001 and 3555 fish in 2002.…”

Osmoregulatory, metabolic, and nutritional condition of summer-run male Chinook salmon in relation to their fate and migratory behavior in a regulated river

“…dams, generating stations) and operations can interrupt a river's natural flow regime, fish habitat, and system connectivity, and thus has the potential to negatively influence the upstream migration of fish, particularly anadromous fish such as salmonids that must travel upriver to natal spawning grounds (Poff et al 1997, Enders et al 2009). Recent studies have demonstrated delays (Thorstad et al 2003, Keefer et al 2004, 2008, Pon et al 2009a or failure of mature adult salmon to reach spawning grounds (e.g. Gowans et al 2003, Thorstad et al 2003 and higher energetic costs for salmonids exposed to variable water flows (Murchie & Smokorowski 2004, Tiffan et al 2010 in regulated rivers.…”