ARTIFICIAL PEOPAGATIOlSr OF TROUT. 33 



rainbow or have been included in brood stocks at the various 

 hatcheries. Federal, State, and commercial. The technical name, 

 Sahno shasta, is used since it appears to be the name of the trout 

 of the McCloud River, from which the original stocks were derived. 



DESCRIPTION. 



The body of the rainbow trout {Sdlmo shusta) is comparatively 

 short and deep and is more elongate in males than in females. The 

 average depth is contained about three and four-fifths times in the 

 body length. The short head, which is obtusely ridged above, is 

 about one-fourth the total length. The mouth is smaller than in 

 other species of Salmo, the maxillary reaching scarcely beyond the 

 eye, Avhich is rather large and is contained five times in the side 

 of the head. The caudal fin is distinctly but not strongly forked. 

 On the vomer are two irregular series of teeth. The dorsal rays 

 number 11 and the anal 10. In the typical species there are about 

 135 scales in the lateral series, with 20 rows above and 20 below the 

 lateral line. In the several subspecies the number of rows of scales 

 along the side is from 120 to 180. The color is variable, depending 

 on sex, age, and character of water. Typical adult fish are bluish 

 above, silvery on the sides, profusely and irregularly dark spotted on 

 the back and sides, the spots extending to the vertical fins, with a 

 red lateral band and blotches and a nearly plain belly. The sea- 

 run fish are nearly plain silvery. The chief distinguishing color 

 characteristics of the varieties are in the number and position of the 

 spots. 



RANGE AND VARIATION. 



The rainbow trout is not indigenous to eastern waters. The 

 natural home of Salmo shasta is in certain tributaries of the Sacra- 

 mento River, and originally it was particularly abundant in the 

 McCloud River, Calif. Other species of the rainbow trout {S. gil- 

 ierti, etc.) occur in the upper San Joaquin River and its tribu- 

 taries. S. gilberti appears to be very similar to S. shasta. 



The rainbow trout is subject to considerable variation in form and 

 color in different parts of its range. Salmo shasta has smaller scales 

 than S. iridevs, a species of steelhead trout inhabiting coastwise 

 streams, and appears to be distinct from the Klamath River trout, 

 which are probably either S. irideus or S. newberri. S. shasta has 

 more than 145 scales in the lateral series, S. irideus has less than 

 135, while S. newherri has about the same number as the lowest 

 count of S. shasta. The proper classification of the so-called rainbow 

 and steelhead series has been the cause of much discussion among 

 ichthyologists,* but it has no place here. 



TRANSPLANTING. 



The rainbow trout was introduced into eastern waters by the 

 United States Fish Commission in 1880, but specimens of it, or its 

 spawn, probably had been brought east by State commissions or pri- 

 vate enterprise prior to that time. Previous to this date the State 

 of New York had established a brood stock of trout from eggs taken 

 in tributaries of the Sacramento River. They were known as Califor- 

 nia mountain trout {SaVnio irideus). In certain streams of the East 



» What are Rainbow Trout and Steelhead Trout? By W. C, Kendall. Transactions of 

 the American Fisheries Society, 1920. 



