CONSERVATION AND ITS MEANING 595 



have they built roads, cleaned up fallen timber and "slash," and cut 

 fire breaks, but they also were on the ground early enough to pre- 

 vent many of the fires from spreading. 



The government agency which has to do with the carrying out of our 

 forest policy is the United States Forest Service, a branch of the 

 United States Department of Agriculture. Forest rangers keep in 

 the field, continually patrolling forest areas. Fire towers are built 

 from which observations are made, airplanes scout during the season 

 of fire hazard in order to locate outbreaks of fire, and trained 

 foresters are constantly at work repairing injured trees, cleaning up 

 areas that are fire hazards, and replanting burned or waste areas with 

 seedling trees. 



Waste and Conservation of Animal Life 



Fisheries 



Fish have been an important food supply since earliest times, but 

 we find that the drain caused by overfishing, commercially as well as 

 in sport, is making severe inroads on the original fish population. 

 Every sportsman well knows that with the coming of the automobile 

 his former haunts have been pre-empted by others and that the supply 

 of game fish has rapidly decreased. To an even greater extent over- 

 fishing has occurred in the oceans, due to the demands of increased 

 population. 



It is well known that fishes change their habitat at different times 

 in the year, a fact which is made use of by sport and commercial 

 fishermen. Although temperature changes and the quest for food 

 play an important part in the migration of some fish, it should be 

 noted that this habit in fishes as in birds seems to be due to the growth 

 of the gonads and the ripening of eggs and sperms. In the ocean, 

 migrations in a general way follow the coast lines. The continental 

 shelf which exists along the eastern coast of the United States, giving 

 rise to the Grand Banks off the coast of Newfoundland, marks the 

 northern limit of the range of immense numbers of food fishes, par- 

 ticularly the cod. Consequently this area of the ocean has been 

 fished to a very considerable degree, being the principal source of 

 pollack, haddock, and cod. 



The relation of the spawning habits of fish to commercial fisheries is 

 important. Many of the most desirable food fish, such as salmon, 

 shad, sturgeon, and smelt, swim in from the ocean up rivers in order 



