296 How to obtain it. 



The further the fish go up rivers of any magnitude the worse it 

 seems to be for them. Some races or species seem to go up the 

 rivers only a short distance, whilst others go rather further, and 

 others again will go more than a thousand miles if they get the 

 chance. One thing is very certain " From the time the salmon | 

 enters fresh water it begins to deteriorate in flesh, and undergoes 

 changes in form and colour." There is a marked difference' 

 between a newly-run fish and one that has been in the fresh water 

 for some time. There is one fact that is specially worth noting, 

 and that is that when the fish running up these large rivers enter j 

 a tributary, and soon find it blocked up by an impassable fall, 

 they will there deposit their ova, whereas had they held on their 

 course up the main stream, they would probably have travelled 

 hundreds of miles further. 



When salmon have done spawning, the sooner they get away 

 to the sea the better. Detention in the river is evidently very 

 bad for them, and they are at such times predisposed to attacks 

 of fungus (Saprolegnia). As sea water is fatal to it, those fish 

 which succeed in reaching the sea before they are attacked are 

 freed from further risks, whilst those which have the fungus 

 actually on them are cured in such cases as have not gone too 

 far. Saprolegnia is somewhat similar to the fungus of diphtheria, 

 and that is very amenable to medical treatment, if taken in time. 

 On the other hand, in cases which have gone too far, or that have 

 been neglected, death usually results. The same applies to 

 Saprolegnia the treatment is the same, the result is the same. 

 On a fish farm it is usually plain to an expert at a glance whether 

 a fish, if properly treated, will live or die. Every fish-qulturist 

 has cases occasionally of Saprolegnia. It is one of the commonest 

 diseases among fishes under certain favourable conditions, and it 

 is much better understood than it was a few years ago. As I have 

 already alluded to it in my chapter on pond life, it would be out 

 of place, however, to go further into the matter here. 



I regret to hear that some of the American salmon rivers 

 have recently been depopulated by the pollution of the water 

 by the lumber companies. Enormous quantities of sawdust 

 being sent down some of the streams the salmon have been 

 absolutely driven out of them. 



