104 REPORT OF STATE BOARD OF FISH COMMISSIONERS. 



perisli, else there will be an increase. If only 2,498 perish there will 

 be two survivors among the offspring of eacli salmon, four for each pair, 

 and the increase will be one hundred fold. The conclusion is, therefore, 

 that while only 15 per cent of the young are destroyed during the help- 

 less stage before they are able to swim, including the egg stage, yet of 

 those that do arrive at the age when they can swim and are supposed to 

 be able to take care of themselves, 99.9 per cent perish before coming to 

 maturity, which is absurd. 



In fact, we know the contrary to be true. We see predaceous fishes 

 and ducks gorging themselves with eggs and with alevins; we find dead 

 eggs in the gravel very much more abundant than live eggs; we see the 

 late spawning fishes tearing up the spawning beds of the earlier spawning 

 fishes and killing the eggs in this way; and we see freshets covering the 

 spawning beds with gravel or washing them away. We do not know, 

 of course, what percentage is destroyed in this way, but none of these 

 mishaps affect artificial propagation. The loss in artificial propagation 

 lies almost wholly in eggs dying during incubation, and it is highly 

 probable that such would die under any conditions. 



Nothing is said above about the completeness of fertilization in natural 

 propagation, for the reason that there are but little data on this point. 

 What little we have point to a high percentage, but it can hardly exceed 

 that of artificial propagation, which is practically complete, 99 per cent. 



I do not mean to claim that artificial propagation is absolutely perfect, 

 that there is no room for improvement; but the question of the improve- 

 ment in methods is hardly pertinent to the present subject. The writer, 

 in his report on the '' Natural History of the Quinnat Salmon in the 

 Sacramento River," gives as his personal opinion that the relative 

 eflPciency of natural and artificial propagation is about one per cent and 

 eighty-five per cent respectively. (Bull. U. S. Fish Com., 1902, p. 137.) 

 Further investigation only shows natural propagation to be of less value, 

 if possible, than there stated. 



There have been enough eggs deposited in the little streams tributary 

 to Karluk Lake, Kadiak Island, Alaska, during the past season that 

 more than two might be placed on each square foot of the surface of the 

 lake, which comprises about fifty square miles ! And this has been the 

 poorest season ever known at that place. Surely if natural propagation 

 approached anywhere near the efficiency of artificial propagation the 

 ocean would be completely overrun with salmon. Think of 2,287,840,000 

 fry coming down one small river ! 



In general, there are two main causes for a scarcity of fish — a dearth 

 of food, and a superabundance of enemies. The food of the growing 

 salmon is largely small fishes. These may be scarce from ineffective 

 propagation, lack of food, or superabundance of enemies, just as the 

 salmon may be. But whatever the cause, if the small fishes are scarce, 

 the salmon will go hungry or seek other feeding-grounds. 



