American Fisheries Society. 77 



ones, for you cannot disinfect them with cliemicals. The cement 

 pond acts merely as a l)arrier against infection, and, as Mr. 

 Bower savs, it might in some way predispose to other diseases; 

 we do not know ahont that. It is untried and the experiment 

 must he made. I do not see liow it couht predispose to some other 

 disease than the one we are trying to prevent. 



Mr. Nevin : At our Bayfiekl hatchery we l)uilt a race ten by 

 two hundred feet, and we had such a good stream of water run- 

 ning through, that with all the fish we handle during the spa^Ti- 

 ing^season, we hardly lost a trout till the middle of May; but 

 from that time to the middle of June we lost a good many. We 

 held the narrow race responsible for this loss at the time. We 

 now have large ponds but we have the same trouble with them as 

 with the smaller ponds. At the Madison hatchery we have the 

 largest loss of fish in one of our best ponds in point of water sup- 

 ply" while in a small stone pond, with a limited supply of water, 

 we carry more fish than in any other. 



Mr. Arthur Svkes: Prof. Marsh, in speaking of the case 

 where they transferred fish from an infected pond to one which 

 was not infected, said the disease abated and that is the experi- 

 ence we have had several times at Madison, that transferring to 

 another pond seemed to stop the disease, and that is true not 

 only of fry but of yearlings. 



The President : Do you know Avhether down in Xew Eng- 

 land among those commercial hatcheries where they use peat for 

 the sides of the ponds, thev have had any difficulty with this 

 disease or not? 



Prof. Marsh: I have l)een told that those commercial 

 hatcheries in Xew England have never had the disease; that they 

 are able to raise l)rook trout successfully; and I imderstood that 

 their ponds were much the same as the ordinary wooden ponds 

 except they were of peat. 



Mr. Clark: These fish, that Prof. Marsh has been working 

 on were from eggs bought from the eastern hatcheries (the year- 

 lings and the fry). 



Mr. Power: There are only one or two hatcheries that use 

 peat, but thev use either peat or wood. 



The President : None of them have stone or cement ; they 



