52 FISH AND GAME COMMISSION 



changes include provision for the installation and maintenance 

 by the division of all screens in ditches except those constructed 

 by the United States and those supplying water for power 

 generation. 



Part and parcel with screen installation is the problem of 

 maintaining and improving some of the older ladders. In the 

 northern part of the State there are many old ladders which 

 should be reconstructed. Most of them were installed according 

 to specifications and in good faith. Many of them have been known 

 to be inadequate, and by law the division is authorized to replace 

 them. 



During the last two years we have removed several abandoned 

 dams in order to make streams passable by fish. The actual removal 

 of these dams is not difficult, but it is a tedious process finding the 

 owners and getting their consent to the removal. Both ladder 

 reconstruction and dam removal should be continued as rapidly as 

 possible. 



e. Rough fish control is one of the newer techniques which has been 

 found very effective in increasing productivity of certain waters. 

 It is usually accomplished through the use of rotenone, the well- 

 known insecticide. Waters can be treated to remove all fish life 

 at a cost for materials of from $0.60 to $1.20 per acre-foot of water. 

 Gull Lake, Mono County, was the first large lake treated. This 

 work was done in 1940, and improved fishing was evident after 

 replanting the following season and continued through the war 

 years. Although rough fish are again present, they have not yet 

 become so aJaundant as to limit trout production. Rehabilitation 

 of lakes and reservoirs by this method is very worthwhile even 

 though the waters may eventually become restocked with rough 

 fish. During the present biennium money has been budgeted for 

 the purchase of poison and a large number of waters have been 

 treated. 



2. The second broad field of activity is that of study and research. 

 The number of questions of fact regarding fish and game that are raised 

 at almost every commission meeting, many of which remain unanswered, 

 are an indication of the continuing need for the gathering of facts about 

 our fishes and fishing waters and their proper management. The Fish 

 Commission of California was establislied in 1870, but no full-time aquatic 

 biologist was employed until 1925. That lone individual worked until his 

 death in 1930, and the division then entered into an agreement with the 

 U. S. Fish and Wildlife Service for what was known as the Cooperative 

 Trout Investigations, and it was not until 1987 that tlie division made any 

 provision in its own organization for the work of trained biologists on 

 fresh-water fishery problems. That staff was reduced to four individuals 

 all during the war period. 



F(jr purposes of organization, the State has been divided into eight 

 districts and eventually it is hoped that it will be possible to place each 

 district in charge of an experienced biologist, who can have two or three 

 assistants. The present assignment ol' tlie i)ermancnt biological employees 

 by districts is indicated on the ioUowing map. 



