Trout and Salmon 183 



ern brook is able to spawn successfully on a lake bottom with 

 a spring seepage, where the other species are not. It is not 

 at all impossible that this is the secret: that the trouts which 

 depend upon a current to carry the protecting gravel over 

 their eggs cannot operate where the only flow is upward j 

 but that the eastern brooks, doing it the hard way, give their 

 eggs the necessary gravel protection without the aid of a 

 current, while the upwelling water suffices to bring the 

 necessary oxygen for the young to develop. 



Steelhead start spawning in the late fall, when the rains 

 which follow the long dry season on the Pacific seaboard 

 bring enough water down the coastal streams to permit them 

 to ascend from the ocean, and continue until spring. Rain- 

 bow spawn in the early spring, and cutthroat slightly later. 

 Brown trout, Dolly Varden, and eastern brook spawn in the 

 autumn and early winter. The eggs of all lie for a long time 

 developing under the gravel which protects them against 

 enemies and light and yet permits the oxygen-bearing water 

 to reach themj even after they have hatched, the little fish 

 remain in the gravel until they have absorbed the nourish- 

 ment in their yolk-sacs, when they are at last ready to wriggle 

 their way up out of the bottom and start life on their own in 

 the open water. These developmental processes take longer 

 in cold water than in warm, but aside from that there is a 

 difference between the species which seems to have some 

 correlation with their life histories. Brook trout eggs develop 

 more slowly than rainbow, even at the same temperature. 

 Brook trout spawn in the fall and their low developmental 

 rate, together with the cold winter water temperatures, keeps 

 the young fish from coming up out of the gravel until the ice 

 is off and food has begun to be plentiful in the early spring j 

 whereas rainbow, spawning in the early spring, develop rap- 

 idly enough in the warming water to get the benefit of the 

 full summer's feeding. 



