THE WAY LIFE BEGINS 29 



building a nest. Most eggs, when left unguarded, are de- 

 stroyed or eaten by other fish. 



Some kinds of sea fish make long journeys up streams or 

 rivers, even going as far as the head waters, to find suitable 

 places to spawn or lay their eggs. The salmon affords one of 

 the most remarkable examples of this habit. There are two 

 kinds of salmon about the American shores; one known as 

 the Atlantic salmon, and the other the Pacific salmon with 

 its several recognized varieties. x 



The Atlantic salmon (see Plate IV) spends most of its 

 life in the sea, but in the early spring, when the female is 

 literally filled with eggs, and the male with sperm, they 

 make their way up the rivers of the North Atlantic coast, 

 leaping cascades and barriers and forcing their way up rapid 

 and shallow stream beds, until the appropriate spawning 

 ground has been found. During this time the males indulge 

 in many fierce combats. Arriving at the spawning ground, 

 the mother salmon scoops away the sand and gravel of the 

 bottom with her tail, and in this nest she lays a few of her 

 six or ten thousand eggs. Then she moves aside, and the 

 male takes her place over the 'nest', and casts his milt quickly 

 upon the eggs, as there is barely time for the sperm to reach 

 them before the envelop surrounding them has become 

 turgid with water and therefore impenetrable to the sperm 

 cells. Sand is then scraped over the eggs, and the pair repeat 

 this process over and over again until all the eggs have been 

 extruded. It may take several weeks to complete the egg 

 laying. 



While the salmon are in fresh water they take little or no 

 food. The Atlantic salmon grow lean and unwholesome in 

 appearance as they make their way back to the sea. The 

 Pacific salmon seldom reach the sea alive. 



How Young Salmon Hatch from the Egg 



The eggs of salmon are about one-quarter of an inch in 

 diameter, and are large for fish eggs. This means that they 

 are well provided with food enough to form the embryo and 



1 Read the story of the Pacific salmon in Science Sketches by David Starr Jordan. 



