HYDRAULIC GEOMETRY AND LONGITUDINAL PATTERNS OF HABITAT QUANTITY AND QUALITY FOR RAINBOW TROUT (Oncorhynchus mykiss)

Abstract

We developed predictions of habitat quantity and quality for three life stages of rainbow trout, Oncorhynchus mykiss, across a range of stream sizes characterized by mean annual discharge of 1 to 50 m3 s−1. The physical habitat template was created by nesting a reach‐scale two‐dimensional hydrodynamic model (River2D) within a downstream hydraulic geometry system using published coefficients for low‐gradient and high‐gradient watersheds. This provided both longitudinal and transverse estimates of depth and velocity profiles that, when combined with habitat suitability curves for the life stages, resulted in predictions of habitat quantity (weighted usable area) and habitat quality (the proportion of the stream profile that provided useable habitat) for rainbow trout along the stream continuum. Habitat quantity increased asymptotically for all life history stages but increased more rapidly in the low‐gradient watershed. Habitat quality decreased non‐linearly for young‐of‐the‐year and peaked at intermediate stream sizes for juveniles in both low‐gradient and high‐gradient watersheds. Adult habitat quality peaked in the high‐gradient watershed but increased asymptotically in the low‐gradient watershed, presumably due to lower mean velocities at larger stream sizes. Incorporation of transverse variation in depth and velocity in our physical habitat template provides a more realistic representation of habitat quantity and quality than do earlier assessments based on simple modal estimates of depth and velocity. Copyright © 2013 John Wiley & Sons, Ltd.

Patterns of fish species distributions replicated across three parallel rivers suggest biotic zonation in response to a longitudinal temperature gradient

“…Water velocity has been commonly used in habitat models for lotic fish as the energy required to manoeuvre in fast-flowing water is higher than in slow-flowing water and can represent a limitation for some species (Clipperton, Koning, Locke, Mahoney, & Quazi, 2003;Hughes, Hayes, Shearer, & Young, 2003;Laliberte, Post, & Rosenfeld, 2014;Rosenfeld & Boss, 2001). Water velocity measurements for the entire SSRB were not available, so river slope was used as a proxy of the average water velocity.…”

Modelling Temperature, Body Size, Prey Density, and Stream Gradient Impacts on Longitudinal Patterns of Potential Production of Drift-Feeding Trout

“…Physical habitat models are most often used for assessing not only how availability of fish habitat changes with flows (Jowett, ) but can also be used to provide a comparison of WUA (i.e. fish habitat quantity and quality) between stream reaches that vary in gradient and stream size (Laliberte et al ., ). To translate WUA into flow management recommendations for fish production or to understand variation in fish production along a continuum in stream size, it is generally assumed that fish population abundance and/or biomass is linearly related to WUA (Bovee and Milhous, ; Anderson et al ., ).…”

Seasonal Movements and Habitat Use of Potamodromous Rainbow Trout Across a Complex Alaska Riverscape

“…The first attribute, channel gradient (GRAD; %) was calculated based on the underlying DEM (Clarke et al 2008). We predicted that gradient would be important over all seasons owing to the propensity for fish to seek areas of optimal flow, food, and dissolved oxygen availability for refugia, spawning, and rearing (Cram et al 2013;Laliberte et al 2014).…”