468 



THE ANIMALS OF THE EARTH 



before the milt reaches them and many of the young fish which 

 develop from the fertilized eggs are greedily eaten by birds and 

 other fish. 



In the early days of America the rivers teemed with fish, 

 but the number rapidly diminished because more and more 

 were caught for food, and fewer and fewer were left to spawn. 

 Within recent years, the government has undertaken to raise 

 fish artificially and has erected fish hatcheries in many places 

 Male and female fish are caught by government fishermen. 



The eggs are gently 

 pressed from the 

 body of the female 

 into a moist bucket, 

 and the milt is 

 pressed from the 

 body of the male 

 and spread over 

 them (Fig. 337). 

 The fertilized eggs 

 are put in water and 

 left to hatch and 

 develop into young 

 fish. The young 

 fish are cared for until they can care for themselves; then-they 

 are placed in near-by streams and lakes or are shipped in large 

 cans to remote streams and lakes. If the hatcheries are large, 

 the fishermen bring in male and female fish and place them in 

 large troughs of running water (Fig. 338), where they remain 

 until they spawn. The adult fish are then removed from the 

 troughs and put back into the streams, and the spawn is left in 

 the troughs to hatch and develop into fry. 



In spite of the fact that the government, through the Bureau 

 of Fisheries, stocks streams yearly with many fry, the supply of 



FIG. 338. Spawning pond, or trough. 



