A length of 20 to 30 inches is typical and a weight of about eight pounds is common. As they grow they get heavier faster than they get longer. They have reached over four feet and a record weight of 57 pounds. Normal life span is four to six years, but that record fish was estimated to be eleven years old.
A Type of Salmon
Rainbow Trout are considered native to the tributaries of the Pacific Ocean in Asia and North America. A range map would be able to use the Continental Divide as the eastern boundary for the range of native Rainbow Trout in North America. In fact they are a type of salmon and many of them are anadromus. That means they swim out to sea and live there several years until they return up to the stream of their birth in order to spawn. The anadromus individuals lose the distinctive pink streak and have a silverfish appearance and are known as Steelhead, but they are the same species of Rainbow Trout. Steelheads can rejuvenate after spawning so they may return to the ocean and repeat the anadromus cycle.
Food and Sport
Trout populations can be adversely affected by habitat loss due to dams, water being pumped from drainages for various uses, water pollution, and even confinement in concrete channels where water is pumped long distances for human use.
The Effects of Drought
Managing to meet the multiple uses of power generation, irrigation, flood control, recreational boating levels and prime fish habitat on one of the best trout streams in the country requires knowing how much water is in the system now, how much there will be at various times in the future and how warm it is going to be and when during the runoff.
But when there is not much water to manage, such as from 2000 to 2005, the trout populations are sure to suffer. With more water, hopefully the upward trends in trout populations will continue.