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McCloud River Rainbow Trout
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The home of this fine trout is in the streams of the Sierra Nevadas from Mount Shasta southward, the limits of its range not well known. It is best known from the McCloud River where it has been handled for many years in the fish-cultural operations of the United States Fish Commission, this being, in fact, the "rainbow trout" of fish-culturists.
Through the operations of the United States Fish Commission this trout has had its range greatly extended. It has been successfully transplanted into many mountain streams in different parts of the United States where it was not previously found, where it grows and multiplies rapidly, as is shown by the many favourable reports. The best results, however, seem to have been obtained from the plants made in Michigan, Missouri, Arkansas, throughout the Alleghany Mountain region, and in Colorado and Nevada. It was introduced into eastern waters in 1880. It is believed this species will serve for stocking streams formerly inhabited by the eastern brook trout in which the latter no longer thrives owing to the clearing of the lands about the sources of the streams, which has brought about changed conditions unfavourable to the eastern brook trout. The rainbow is adapted to warmer and deeper waters, and is therefore suited to many of the now depleted streams which flow from the mountains through cultivated valleys.
Rainbow trout differ widely from brook trout and other pugnacious fishes in that they feed largely upon worms, larvae, crustaceans, and the like, and do not take so readily to minnows for food. They should be planted in spring or early summer when their natural food is abundant. They will then grow more rapidly and become accustomed to life in the stream, and when worms, larvae, etc, are no longer to be found, their experience and size will enable them to take anything in the shape of food that may present itself. Fish hatched in December and January can be safely planted in April or May.
The size of the rainbow trout varies greatly, depending upon the volume and temperature of the water, and the amount and character of the food-supply. In the streams of the Sierras, where it is native, it reaches a length of 10 to 30 inches, and a weight of 2 to 8 pounds. The average weight of those caught from streams in the East is probably less than a pound, but examples weighing 63/4 pounds have been taken. In the Ozark region in Missouri they are caught weighing 5 to 10 pounds. In some of the cold mountain streams of Colorado their average weight is but 6 or 8 ounces, while in certain lakes in the same State, where the water is moderately warm, and food is plentiful, they reach a length of 25 to 28 inches, and a weight of 12 to 13 pounds. In the Au Sable River in Michigan they reach a weight of 5 to 7 pounds. The largest example ever produced in the U.S. Fish Commission ponds at Wytheville, Virginia, weighed 6 1/2 pounds.
The average growth of the rainbow trout under favourable artificial circumstances is as follows: One year old, from 3/4 to 1 ounce; 2 years old from 8 to 10 ounces; 3 years old from 1 to 2 pounds; 4 years old from 2 to 3 pounds. Like all other fishes, they continue to grow, at least until they are 8 or 10 years old, the rate diminishing with age. Some, of course, grow much faster than others, even under the same circumstances, but the rate of growth, as with all fishes, is largely a question of temperature, food, and extent of water-area. In water at 60 degree, with plenty of food, fish 1 or2 years old will double their size several times in a single season; while in water at 40 degree, with limited food, the growth is very slow indeed.
The rainbow like the brook trout, will live in water with a comparatively high temperature if it is plentiful and running with a strong current; but in sluggish water, even when the temperature is considerably lower, neither species will do well. The rainbow however, will live in warmer water then the brook trout, and is often found in streams where the temperature is as high as 75 degree even 85 degree, especially where there is some shade. The water of the streams in which the rainbow is native, varies in temperature from 38(degree), in winter to about 70 degree, In summer. For hatchery purposes spring water, with a temperature from 42 to 58, is best.
The spawning season of the rainbow trout in California extends from early February to May. A curious change in the season has occurred with those cultivated in the East. In Colorado the season is from May to July, while at Wytheville it extends from early in November to the end of February.