1 62 ANIMAL BIOLOGY 



out further care are frequently compelled to produce 

 enormous numbers of eggs to make good the great loss 

 due to lack of protection. The forms which lay their 

 eggs in nests or guard them after they are laid lay com- 

 paratively few eggs. 



Some fishes make extensive journeys before depositing 

 their eggs. The Columbia River salmon during the spring 

 of the year leaves the ocean, where it spends a great part 

 of its life, and entering the mouth of a river quickly swims 

 up stream. In the beginning of their journey the fish 

 are well fed and full of vigor ; they require all their stored-up 



FIG. 130. Quinnat salmon. (From the Report of the Calif. Fish and 

 Game Commission.) 



supply of energy, since they take no food after entering 

 the fresh water. When the salmon are "running," the 

 water may be densely crowded with them, and the fisher- 

 men whose canneries line the banks of the Columbia 

 River reap a rich harvest, for they have their nets spread 

 for the unwary travellers and haul them in by hundreds 

 of tons. Those fortunate enough to escape being made 

 up into canned salmon, press on through rapids and often 

 leap over low falls until they reach the smaller tributaries 

 of the stream, in many cases over one thousand miles 



