THE SALMON. 97 



trout and salmon ; there are certain prerequisites to the 

 continuance of the species that must be complied with. 

 The fish must ascend to the fresh water to spawn, and if 

 prevented by an improperly constructed dam, will quit 

 the locality never to return. 



It should be known that, contrary to the usually 

 received opinion, salmon cannot surmount a fall of much 

 over ten feet ; this, probably, is the full extent of their 

 powers. And in effecting this, much depends upon the 

 depth of water at its foot ; the deeper it is the higher 

 they can leap. They do not take their tails in their 

 mouths, according to the ancient theory, to enable them 

 to spring higher, but rush with their utmost velocity 

 from the bottom, and are carried by their momentum a 

 considerable distance out of water. Such a leap or a 

 struggle against strong rapids weakens them, and they 

 must soon rest to recover strength for another ascent. 

 They thus congregate below each fall, and often make 

 many efforts before they overcome it. They usually 

 move at night or early in the morning. A dam of fif- 

 teen or twenty feet will effectually exclude them from 

 any stream, but may be rendered innocuous at small 

 expense by placing below the wasteway boxes of heavy 

 wood, with a fall of not over five feet from one to the 

 other. A salmon leaps from the river to the first, from 

 that to the next, and so on till he has overcome the 

 barrier. A broad sluiceway leading at a moderate 

 i,ngle to the pool below, will probably answer as well.* 



The fish, as they enter the rivers, may be deterred 

 .rom entering, or all captured in nets spread entirety 

 across the mouth, and when those that do pass have 



* See Post as to modern fishways. 



