Pacific salmon are powerful, and yet they are fragile. Conditions in the natal stream must be perfect. If the water is too hot or too cold, has too much dissolved oxygen or too little, or if the currents are too strong or too gentle, the salmon will perish. Today few rivers are perfect around the Pacific Rim.
The stands of Douglas fir, northern red cedar, and lodge pole pine that shade and cool salmon streams are cut and sent to mills.