Evidence of Delayed Mortality on Juvenile Pacific Salmon Passing through Turbines at Columbia River Dams

Abstract

We evaluated the survival of juvenile salmon through turbines in Columbia River dams and found no differences between two operations but strong evidence of delayed mortality from turbine passage. After tagging with a passive integrated transponder (PIT) tag and a radio tag, yearling Chinook salmon Oncorhynchus tshawytscha were released at McNary Dam on the Columbia River through a turbine operating both within 1% of peak efficiency (a discharge rate of 317 m3/s) and outside the 1% range at the maximum blade angle (464 m3/s). Estimated relative survival to a detection array 15 km downstream was 0.871 at 317 m3/s and 0.856 at 464 m3/s and 0.858 and 0.814, respectively, to an array 46 km downstream. The highest point estimates of survival occurred under the lower discharge, suggesting that operating turbines within 1% of peak efficiency is a useful guideline for fish protection at McNary Dam. In a concurrent evaluation using balloon tags, estimated mean direct survival ranged from 0.930 to 0.946. Radio tag estimates were significantly lower than balloon tag estimates under both operations. Based on these differences, we estimated that delayed mortality comprised from 46% to 70% of total estimated mortality. We reviewed the literature and concluded that delayed mortality was caused by sublethal impacts to fish sensory systems, which increased vulnerability to predation in the tailrace. We recommend that future research to improve turbine designs and operations for fish passage focus on this major component of mortality.

Temporal variation in fish community in the tailrace at Três Marias Hydroelectric Dam, São Francisco River, Brazil

“…In most hydroelectric dams, it is common to see large concentrations of fish aggregation downstream from the dam, in the tailrace (Agostinho et al, 2007). The presence of these aggregation is a concern for the electric energy segment because many power dams operations put ichthyofauna at risk (Ferguson et al, 2006;Schilt, 2007;Loures, 2009).…”

“…However, few studies have investigated the fish community in the tailraces of dams and how their knowledge can help reduce the impacts generated by its operation (Ferguson et al, 2006;Schilt, 2007;Nestler & Goodwin, 2001). Thus, we evaluate temporal variations in fish community immediately downstream from the Três Marias Hydroelectric Dam on the species composition and abundance and their relationships with abiotic variables.…”

Habitat Choice by Atlantic Salmon Parr in Relation to Turbulence at a Reach Scale

“…With their streamlined body shape, salmonids are evolutionarily well adapted to severe velocities and velocity fluctuation, and may use shear stress and turbulence to their advantage while swimming head-on into the flow (Liao et al 2003). However, if flow is coming from behind or at extremely high levels (e.g., in hydroelectric turbines), shear stresses can lead to sublethal physiological effects on fish equilibrium (Ferguson et al 2006), lift and tear off scales, pry open the operculum, rupture or dislodge eyes, and damage gills (Odeh et al 2002;Neitzel et al 2004;Deng et al 2005). Maps of these four turbulence variables were created using linear interpolation in Vertical Mapper 3.0 in MapInfo Professional 7.0.…”

A conservation plan for Atlantic salmon (Salmo salar) and anadromous brown trout (Salmo trutta) in a region with intensive industrial use of aquatic habitats, the Hardangerfjord, western Norway

“…In some rivers, the water inlet to the hydroelectric power station has been designed to maximize water intake without any attempts to allow descending fish to bypass. As a result, large numbers of smolts and overwintering fish may be seriously injured or killed as they pass through the turbines (Ferguson et al 2006). Old dams without fish passage still exist in some rivers.…”