54 KEPORT OF THE COMMISSIONER OF FISHERIES. 



INVESTIGATIONS OF LAKES AND STREAMS. 



During the fiscal year the investigation of Lake Simapee, N. H., 

 was brought to a close. This was undertaken to determine tlie effects 

 of the introduction of various species of Sahnonidse not indigenous 

 to the lake, especially in respect to the permanence of the species so 

 introduced. Among those was the cliinook salmon of the Pacific 

 coast, small plants of which have been made more or less regularly 

 for a number of years at the earnest solicitation of persons interested 

 in maintaining the supply of fishes in tliis body of water. The species 

 has become established in the sense of the survival of a number of 

 individuals sufficient to supply a considerable catch by sportsmen, 

 but there is no indication that they have ever spawned or are likely 

 to spawn under the landlocked conditions obtaining. To maintain 

 the supply it would, therefore, be necessary to make annual or frequent 

 plants. As the species feeds more or less on other game fishes 

 indigenous or previously introduced, a continuation of planting 

 would probably merely substitute a wholly artificial supply of fisli for 

 one naturally maintained. A somewhat similar condition exists 

 with respect to one or two other fishes in the lake. 



The investigation of lakes in Idaho and Washington, undertaken 

 at the request of State and local authorities, developed interesting 

 facts bearing on the adaptabifity of the waters for fish culture and 

 the introduction of nonindigenous species. The work will be com^ 

 pleted and reported on early in the next fiscal year. Work on 

 similar fines was conducted in Wisconsin in cooperation with the 

 Wisconsin geological and natural history survey. 



The investigation of the Ilhnois River with special reference to 

 the effects on fish fife of the sewage discharge and the drainage 

 changes induced by the Cliicago drainage canal, begun in the preced- 

 ing fiscal year in cooperation with the natural history survey of 

 Ilhnois, has been continued. It has been found that in the upper 

 part of the river the conditions are essentiaUy those of a septic tank, 

 the stream practically devoid of oxygen and therefore of fish. In 

 the lower part the conditions gradually improve through the oxy- 

 genation of the water, and fish are found in increasing numbers. 

 The results of this work when completed will have wide apphcation 

 to the conservation of fishes in sewage-laden streams throughout the 

 country. 



Investigations in the Truckee River Basin showed that owing to 

 changes in the drainage due to irrigation projects the current in the 

 lower river had been checked and diverted to such an extent as to 

 interfere seriously with the migration of certain fishes wliich constitute 

 a valuable food supply, especially to the Indians. The impounding 

 of the water of Lake Tahoe and the diversion of large quantities at 



