THE RELATIONS OF FISH TO MAN 



291 



over honeycomb rock, and since many of them are covered by 

 sediment or fall prey to mud puppies, yellow perch, crayfishes, 

 and other enemies, very few develop into adult fish. Because 



FIG. 172. Whitefish. (From U. S. Fish Manual.) 



of this fact the government each year gathers, rears, and dis- 

 tributes millions of whitefish eggs. Whitefishes are captured 

 in deep water by means of gill nets which hold the fish just be- 



FIG. 173. Lake trout. (From U. S. Fish Manual.) 



hind the gill covers. The average weight is about four pounds, 

 but they may become as heavy as twenty pounds. 



The lake trout (Fig. 173) is another important food fish of 

 the Great Lakes region. It is the largest of our trouts, averag- 



