PROPAGATION AND DISTEIBUTION OF FOOD FISHES, 1922. 107 

 PLANTING OF FISH. 



When planting fish, sudden change in temperature should be 

 avoided. This may be done by pouring some of the water from the 

 cans and slowly adding water from the stream or lake in which 

 the fish are to be deposited. The change of temperature should be 

 gradual, not less than half an hour being consumed in modifying 

 it 10°. In a stream it is best to deposit a few fish in each of several 

 places as near as possible to the heaclw-aters or in small tributaries." 

 In lakes or ponds they should be scattered in shallow places where 

 the water is not stagnant. Localities should be selected where the 

 fish will have a supply of natural food and be immune from attacks 

 of enemies. 



COOPERATION WITH VARIOUS AGENCIES. 

 UNITED STATES FOREST SERVICE. 



The major portion of fish distributed in Colorado, New Mexico, 

 and Arizona is handled by forest rangers, who meet the consign- 

 ments at railroad stations and carry the fish to the headwaters of 

 streams. The method of keeping the headwaters of streams well 

 stocked is productive of highly satisfactory results. The young 

 fish are afforded suitable surroundings with abundance of natural 

 food, they are free from the attacks of other fish, and they are, by 

 virtue of the inaccessibility of the headwaters of many streams, 

 out of reach of the angler. When the headwaters become over- 

 stocked, the large fish drop downstream in search of food, where 

 they may be taken by anglers of the more populous districts. The 

 idea of using the headwaters of streams as breeding and rearing 

 grounds for the various species of trout is being followed wherever 

 practicable. The plan possesses great possibilities and seems to be 

 the only method whereby trout can be maintained in certain streams 

 in view of the annual increase in the number of anglers. 



NATIONAL. PARKS. 



Until within comparatively recent years the full possibilities of 

 our national parks as fish preserves have not been given the serious 

 consideration to which they are entitled. Realizing the necessity of 

 maintaining a supply of fish in the waters of national parks, where 

 fishing has become intensive during the open season, the bureau has 

 established field stations in Yellowstone and Glacier Parks where 

 skilled fish-culturists are temporarily detailed to make collections of 

 and incubate the eggs of the various species of trout, the resultant 

 fry being liberated in the waters most suitable for the particular 

 species involved. 



The National Park Service is now actively engaged in a most in- 

 tensive campaign of fish-cultural development in cooperation with 

 the bureau's hatcheries in Yellowstone and Glacier National Parks. 



RAILROADS. 



For a number of years the important railroads of the country have 

 granted the bureau the privilege of carrying in baggage cars in pas- 

 senger trains shipments of fish when accompanied by attendants, 



