198 American Fisheries Society 



these fish are adapted and which they cannot transcend. It has been a 

 matter of considerable wonder for a number of years that we have fish 

 from the Pacific coast which appear to have changed their habits when 

 they have been sent east, and that fish raised from eggs from the McCloud 

 River in California, instead of spawning in January, February, March, 

 and April, or even May, as they do in the McCloud, have approached the 

 spawning time of the common brook trout, namely, the latter part of 

 October, November, December, January, and so on. But the truth is, as 

 it seems to me, that they have not changed their habits ; they are 

 simply trying to conform to the temperature that prevails at the new 

 location. The fish mentioned by Mr. Rowe were probably adapted to a 

 certain temperature that prevailed at that time of spawning. 



Of course, there are many other factors that may affect the time of 

 spawning, but temperature is one of them and a very important one. 

 As a matter of fact, steelhead trout derived from northern fish on the 

 Pacific coast spawn in the spring in northern waters in the east, and 

 they do pretty well. But we have more or less difficulty with the 

 rainbow trout. In the McCloud River the teftaperature of the water is 

 more uniform throughout the year. The fish there spawn not on a rising 

 temperature but on a falling temperature of the water, because the 

 spring water is colder than the water in winter and the rainbow and 

 steelhead trout spawn at the season, wherever they happen to be, on 

 a falling temperature. It viras stated in an old report of the Bozeman, 

 Mont., hatchery that the temperature was very uniform throughout 

 the winter, and that in the spring it was one or two degrees or more 

 colder, because of the melting snows. So the water in the spring is 

 probably colder than it is when there is no melting snow or ice. It was 

 at this time the rainbows were said to spawn at Bozeman. 



Mr. Rowe: I was wondering whether that would prove that one 

 was rainbow and the other steelhead. 



Mr. Titcomb: It was at the Wytheville hatchery that the rainbow 

 trout was originally domesticated in the east to any extent, so far as I 

 know. As I understand it, the fish originally spawned rather lat€ in the 

 spring. The water is all spring water, and there is very little variation 

 throughout the season. As the fish became domesticated and accustomed 

 to that even temperature, they gradually began to spawn earlier and 

 earlier. When I was in charge of fish-cultural work at Washington 

 I recall that we looked upon it as unusual when eggs were obtained by 

 the first of December. Since that time, the fish have been spawning even 

 earlier than that. It seems to me that the change may be due to the 

 unnatural conditions of water temperature there, and the lack of any 

 unusual changes which we get in the wild streams. The steelheads in 

 the wild waters, so far as we know, all spawn late in the spring, because 

 we have cold winters there, and the fish do not spawn until the water 



