TWENTY-NINTH BIENNIAL REPORT. 59 



first by the Nevada Commission. As near as the writer can determine 

 the Nevada and California commissions introduced them at about the 

 same time. Some of these fish were introduced into Fallen Leaf Lake 

 where they found suitable breeding grounds as the young of the 

 Mackinaw trout were caught frequently. Very few were taken from 

 Lake Tahoe. Occasionally a Mackinaw trout would be caught, but they 

 were so rare for many years after their introduction, that the writer 

 was of the opinion that they could not find suitable grounds on which 

 to spaAvn and that the few that were taken, descended from Fallen 

 Leaf Lake to Lake Tahoe. Mackinaw trout do not ascend the streams 

 to s])awn, but deposit their eggs on reefs in water from 4 to 6 or 8 

 feet in depth. As such places are unknown in Lake Tahoe, it was 

 supposed that the Mackinaw trout would never be taken in any 

 numbers, but during the last seven years, 24 years after their introduc- 

 tion into the lake, they are appearing in ever-increasing numbers, 

 n^his summer they were being caught at many different places in the 

 lake. They have evidently found suitable breeding grounds and are 

 increasing rapidly. The Mackinaw trout is one of the large charrs, 

 native of the lakes of northeast America. The type introduced into 

 Lake Tahoe are natives of Lakes Superior and Michigan. They are 

 a good food fish and afford sport for those who enjoy trolling for fish 

 in deep water. Occasionally they reach a weight of from 50 to 60 

 ])onnds, but the average weight of the adults is about 20 pounds. 

 As tliey are piscivorous in their habits, devouring a large number of 

 other fish, they will have an abundance of food in Lake Tahoe because 

 of the countless millions of minnows and chubs. As they inha])it deep 

 water during the greater portion of the year, they may not devour as 

 many of the native species of trout as is generally supposed, but a 

 biological survey and a study of their habits will be carried out this 

 coming summer to determine what proportion of their food is com- 

 posed of the native species of trout and what proportion is minnows 

 ai]d chubs. 



Hat Creek and Fall River. Considerable comment has been made 

 i-egarding the conditions on Hat Creek and Fall River and the absence 

 of screens in the canals leading to the power houses operating on these 

 streams. This department has always contended that the trout in Fall 

 River and Hat Creek were nonmigratory and that they do not descend 

 tliese canals and pass through the impulse wheels of the power plants 

 and thus get destroyed as is claimed by others. The nature or 

 physical condition of these streams, in our .judgment, has changed the 

 habits of the trout to such an extent that they do not migrate 

 from one portion of the stream to another or pass out of the streams 

 into Pit River. The water in these streams comes from large springs 

 that furnish the entire flow of Fall River. A greater portion of the 

 water in Hat Creek above the Power Company's canals comes from 

 Rising River, a short river that rises from a large spring in the lava. 

 .Rising River is only two miles in length from its source in one of the 

 largest springs on the coast to where it unites with Hat Creek, a stream 

 that rises on the north basal slopes of Mount Lassen. The fish in Hat 

 Creek above the confluence of the two streams, do not descend the 

 stream to where the main streams flow into the junction, nor do the 

 fish in Rising River ever leave the main stream, except the emaciated 

 and dying spawn fish that die each year after their efforts to propa- 



