The influence of water velocity on the downstream movement of alevins and fry of brown trout, Salmo trutta L.

Abstract

Trout eggs were planted in four experimental stream channels, each channel being run at a different but constant discharge. Survival of the eggs to hatching was low and apparently unrelated to surface water velocity. However, movement of young trout out of channels was affected by water velocity, the higher the velocity the greater the proportion of trout that were lost. Virtually all fry moved out of a channel with a mean surface water velocity of 0.73 m s-'. The rate of loss was not constant over the experiment but increased as the young trout entered the free-feeding stage. At the end of the experiment loss of fry, after abrupt increases in discharge, was demonstrated in the lower velocity channels.

Native Riparian Tree Establishment Along the Regulated Dolores River, Colorado

“…While the increased downstream movement of salmonid fry under high streamflows has been repeatedly documented (e.g. Ottaway & Forrest 1983, Irvine 1986, Crisp & Hurley 1991a, the role of substrate complexity has been rarely addressed (but see Meyer & Griffith 1997). However, irrespective of substrate complexity, the tendency for downstream movement was higher in winter for both species, which is well in accordance with Heggenes and Traaen's (1988) finding that salmonid fry are able to withstand higher velocities at higher water temperatures.…”

Spatial and temporal variation in the relative density and size of juvenile brown trout in the Kakanui River, North Otago, New Zealand

“…1A). Rapid dispersal of fry alone can not explain this result because initial dispersal of fry is in a downstream direction (Elliott 1966;Ottaway & Forest 1983) and yet in 1992 and 1993 highest initial densities were found up stream from the main concentration of redds. There are two explanations for the variation in initial fry distribution.…”

“…In addition to scouring eggs and alevins from the substrate, floods could impair the survival of emergent fry. The emergent fry stage is known to be a critical time for survival (Allen 1951;Elliott 1989;LeCren 1965) and emergent fry are very susceptible to downstream displacement by high flows (Ottaway & Clarke 1981;Ottaway & Forest 1983;Heggenes & Traaen 1988). Stephens (1989) reported reductions in 0+ rainbow trout densities in the Tongariro River associated with flooding which appeared to be most severe at the early fry stage.…”

Distribution and movement of domestic rainbow trout, Oncorhynchus mykiss, during pulsed flows in the South Fork American River, California

“…These pulsed flows may impact the behavior of resident or migratory fish, particularly juvenile salmonids, by forcing them downstream (McCrimmon 1954;Erman and Leidy 1975;Ottaway and Clarke 1981;Ottaway and Forrest 1983;Heggenes and Traaen 1988;Crisp 1991;Crisp and Hurley 1991;Pearsons et al 1992). This may result in increased mortality, decreased growth, or decreased reproduction.…”