WHAT ARE RAINBOW TROUT AND STEELHEAD 



TROUT? 



By Dr. William Converse Kendall 



Scientific Assistant, U. S. Bureau of Fisheries 



Washington, D. C. 



Whenever the trouts of certain localities are studied, diffi- 

 culties are encountered in an effort to make the specimens 

 conform to the classification. Gilbert refers to the trout and 

 whitefish as "two forms which seem to be superior to any dis- 

 coverable law of distribution." Gilbert and Evermann again 

 say (1894) that with every additional collection of black 

 spotted trout, it became increasingly difficult to recognize any 

 of the distinctions, specific or subspecific, which had been set 

 up; that their collections added not a little to the difficulty and 

 they were convinced that the greater number of the subspecies 

 of S. mykiss, which the common redthroat trout was then 

 called, had no sufficient foundation. On the other hand, in 

 1896, a comparison of many specimens of "Salmo mykiss 

 clarkii" indicated to Evermann and Meek that it would be 

 necessary to recognize more species or varieties of Salmo in 

 the northwestern portion of the United States than have 

 hitherto been admitted. 



The specific identity or distinctness of the rainbow and steel- 

 head trouts has been the subject of long discussion and of 

 varied and varying opinions. In 1919 Jordan wrote that on 

 this question he had at different times held different opinions. 

 His final judgment was that the coastwise trout of California 

 are the young of the species which in the sea and large rivers 

 is called steelhead, Salmo rivularis, and the original rainbow 

 was therefore the young of Salmo rivularis, or as it used to be 

 called, wrongly he believed, Salmo gairdneri. "As irideus 

 (misspelled iridia) is the oldest name," he said, "it must stand." 



