Redband trout, Oncorhynchus mykiss gairdneri, population and stream habitat surveys in northern Owyhee County and the Owyhee River and its tributaries, 1997 /

Abstract

Redband trout Oncorhynchus mykiss gairdneri were collected in ten of seventeen stream segment sampled in 1997. Densities of redbands ranged from to 31.0/100M 2 for all sizes of trout collected. Seven of the sites visited had been sampled since 1993 in this study, and generally trout densities had increased. The sample sites were located on Jordan Creek, Flint Creek, Reynolds Creek, Macks Creek, Salmon Creek, Squaw Creek, Sinker Creek, Scotch Bob Creek. Deep Creek, Red Canyon Creek, and the North Fork Owyhee River. The Owyhee River was sampled by angling from the Duck Valley Indian Reservation to the Oregon border by utilizing small inflatable rafts, few redband trout were captured.Habitat information was collected on most stream segments sampled.Water quality measurements of temperature, pH, conductivity, and hardness were taken and values were acceptable for trout survival. Eight recording thermographs were placed into stream segments that were sampled for redband densities. Two of the thermographs recorded water temperatures consistently greater than 25 C. One of these streams had a redband population the other did not.

Coastal Cutthroat Trout Redd Counts Impacted by Natural Water Supply Variations

“…Droughts reduced Brook Trout growth and survival in headwater streams of West Virginia, including longer-term (winter and postdrought) food reduction and sedimentation impacts (Hakala and Hartman 2004) that may likewise apply to Pacific salmonids (McDonald 1960;Erman et al 1973). Seasonal and interannual fluctuations in abundance of Redband Trout (inland Rainbow Trout) and resident Bull Trout both corresponded to whether normal or drought conditions prevailed in Idaho desert streams (Warren and Partridge 1993;Allen et al 1995Allen et al , 1997Zoellick et al 1996), similar to the interannual fluctuations of Brown Trout in a Wisconsin stream (Lowry 1971). Rainbow Trout and Cutthroat Trout often leave lotic rearing sites to enter main-stem habitats and associated lakes HYDROLOGY IMPACTS ON REDD COUNTS when streamflows decrease over the summer-fall (Benson 1960;Bulkey and Benson 1962;Erman and Hawthorne 1976;Berger and Gresswell 2009). Besides being influenced by the great reduction in Irely Lake area and volume during dry-outs, the Coastal Cutthroat Trout run may also decline with creek habitat during summerfall given that some reaches in the lower main stem are intermittent during dry years.…”

Resource supply and organismal dominance are associated with high secondary production in temperate agricultural streams

“…Hence, it is likely that stone loach as a benthivorous species (Smyly, 1955) in the agricultural stream Getel had a stronger effect on MSP (Dudgeon, 1993) than the dominant fish species brown trout had on MSP in the forested streams. As a result, the estimated MSP has to be evaluated in the light of predation intensity and, more specifically, Allen's paradox, which states that fish consume more macroinvertebrates than apparently produced within a stream (Allen, 1951). When incorporating the ideas of Allen (1951) and subsequent work by Huryn (1996), who added alternative resources such as terrestrial prey and conspecifics to explain the paradox, secondary production was likely higher in streams with higher fish stocks.…”

“…As a result, the estimated MSP has to be evaluated in the light of predation intensity and, more specifically, Allen's paradox, which states that fish consume more macroinvertebrates than apparently produced within a stream (Allen, 1951). When incorporating the ideas of Allen (1951) and subsequent work by Huryn (1996), who added alternative resources such as terrestrial prey and conspecifics to explain the paradox, secondary production was likely higher in streams with higher fish stocks. That suggests that the difference in secondary production between the agricultural stream Sauerbach and the three other streams would be effectively lower without considering predation by fish.…”

A Long‐Term Comparison of Redband Trout Distribution, Density, and Size Structure in Southwestern Idaho

“…Redband trout were probably rare in large streams because of elevated stream temperatures Tait et al 1994). The loss of connectivity between streams and redband trout populations is thought to be one of the greatest threats to the long-term persistence of redband trout in southwestern Idaho Allen et al 1998). Static to declining populations at low elevations highlight the importance of maintaining existing connections between redband trout populations and habitats, so that redband trout emigrating from higherelevation or more productive populations can contribute to sustaining low-elevation populations through time (Dunham et al 1997).…”