Are trout populations affected by reach-scale stream slope?

Reach-scale stream slope and the structure of associated physical habitats are thought to affect trout populations, yet previous studies confound the effect of stream slope with other factors that influence trout populations. We isolated the effect of stream slope on trout populations by sampling reaches immediately upstream and downstream of 23 marked changes in stream slope on 18 streams across Wyoming and Idaho. No effect of stream slope on areal trout density was observed, but when trout density was expressed volumetrically to control for differences in channel cross sections among reaches in different slope classes, the highest densities of trout occurred in medium-slope reaches, intermediate densities occurred in high-slope reaches, and the lowest densities occurred in low-slope reaches. The relative abundance of large trout was reciprocal to the pattern in volumetric trout density. Trout biomass and species composition were not affected by stream slope. Our results suggest thatan assumption made by many fish-habitat models, that populations are affected by the structure of physical habitats, is at times untenable for trout populations in Rocky Mountain streams and is contingent upon the spatial scale of investigation and the population metric(s) used to describe populations.

作 者：

Isaak DJ.；Hubert WA.

刊 名：

Canadian Journal of Fisheries and Aquatic Sciences 

年，卷(期)：

2000Vol.57,No.2,2000("") 

分类号：

 

关键词：

Brook trout  Brown trout  Salvelinus-fontinalis  Habitat utilization  Physical habitat  Mountain streams  Northern idaho  Salmo-trutta  Gradient  Classification

正文语种：

eng 

基金项目：