Influence of forest and rangeland management on anadromous fish habitat in Western North America: habitat requirements of anadromous salmonids.

Abstract

Habitat requirements of anadromous and some resident salmonid fishes have been described for various life stages, including upstream migration of adults, spawning, incubation, and juvenile rearing. Factors important in the migration of adults are water temperature, minimum water depth, maximum water velocity, turbidity, dissolved oxygen, and barriers. Habitat requirements for successful spawning are suitable water temperature, water depth, water velocity, and substrate composition. Cover—riparian vegetation, undercut banks, and so on—is needed to protect salmonids waiting to spawn and may influence the selection of spawning locations. Incubation requirements incorporate both extra- and intragravel factors. Extragravel factors are: dissolved oxygen, temperature, velocity, discharge, and biochemical oxygen demand of the stream. Intragravel factors are dissolved oxygen, temperature, permeability, apparent velocity, and sediment composition.Important habitat components for juvenile rearing are fish food production areas, water quality, cover, and space. Good fish food production areas are mostly riffles with water depths of 0.15-0.91 m, water velocities of 0.30-0.46 m/s, and substrates of coarse gravel and rubble (3.2-30.4 cm). Good water quality for rearing salmonids includes mean summer water temperatures of 10.0°-14.0°C, dissolved oxygen at more than 80-percent saturation, suspended sediment less than 25 mg/liter, and fine sediment content of riffles less than 20 percent. Adequate cover—in the form of riparian vegetation, undercut banks, aquatic vegetation, and rubble-boulder areas—is needed to protect juvenile fish from predation and adverse physical factors.

Citation

Reiser, D.W.; Bjornn, T.C. 1979. Influence of forest and rangeland management on anadromous fish habitat in Western North America: habitat requirements of anadromous salmonids. Gen. Tech. Rep. PNW-GTR-096. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 1-54