196 American Fisheries Society 



Discussion 



Mr. J. W. TiTCOMB, Albany, N. Y. : What is the effect of inbreed- 

 ing these different forms? 



Dr. Kendall: A difficulty attributed to inbreeding is a gradual 

 reduction in the egg yield of brood fish. Now, whether that is attri- 

 butable to this mixture or not, we do not know ; that is one of the 

 problems we shall try to solve. But it is quite possible that the 

 descendants of these hybrids would have a reduced egg yield, and that 

 complete sterility of the fish might finally result. 



Mr. Titcomb: We have some stock in New York where we have 

 mixed the two kinds of trout ; in fact, we are planting them regardless 

 of whether they are rainbow or steelhead. 



Dr. Kendall: So far as classification is concerned, the books are 

 wrong. The steelhead trout is the one that has the coarser scales. I 

 have counted the scales of various steelheads from the different rivers, 

 including types from the coast ; the scales run about 130, a few more or 

 less according to the locality. The McCloud River rainbow was intro- 

 duced early into Europe and elsewhere. It has scales numbering about 

 160 in the lateral line. 



Mr. Titcomb: Am I correct in understanding that the so-called 

 rainbow trout was introduced into New Zealand where some of these 

 fish have been known toi weigh 25 pounds? I understand that after they 

 had been called rainbow trout for a great many years there, it was 

 decided that they should be called steelhead. 



Dr. Kendall : I remember the time when it was decided that the 

 New Zealand rainbows were steelheads. Two mounted specimens were 

 sent to the Bureau of Fisheries, at Washington, and for a long time they 

 hung on a wall in the laboratory. One day Dr. Evermann looked at 

 them and said that they were not rainbows, that they were steelheads; 

 and henceforth the New Zealand rainbows were steelheads. Possibly it 

 may be significant that this decision was made at a time when the steel- 

 head was supposed to have the finer scales, and the conclusion may have 

 been based upon that character. If so, the fish were probably rainbows. 

 But to determine the matter definitely it would be necessary either to 

 count the scales or to know the locality from which the fish were originally 

 obtained. A leopard cannot change its spots ; the rainbow trout of 160 

 scales cannot change its scales to 130 or 120. 



Mr. Titcomb: When you cross the rainbow and steelhead, are you 

 going to produce a hybrid that will not breed? 



Dr. Kendall: Some hybrids do breed. It has been determined that 

 they will breed, with a reduced egg yield and inferior fry. I have had 

 no experience in that line, but other fish culturists have, in Europe, 

 England and other places. Francis Day relates a number of instances of 

 crossing trout of different species, but in no instance did he get per- 

 fectly satisfactory progeny that were continuously fertile. 



Mr. Titcomb: You do not know anything then, about the results 

 of mixing the steelhead and rainbow trout? 



