42 American Fisheries Society. 



Mr. Titcomb: That applies to other species as well? 



Dr. Osburn: Yes, many of the marine species. Almost always 

 the females would die off first. For instance, we kept striped bass until 

 some were more than twenty years old, and all we had left at the end 

 were a number of old males. 



Mr. Titcomb: With regard to parasites, you referred to the desira- 

 bility of using spring water and keeping the adults in the lower ponds; 

 you would move these adults to the upper ponds for breeding purposes? 



Dr. Osburn: Yes. 



Mr. Titcomb: Do they carry the parasites with them? 



Dr. Osburn ; If they do, they would not in most cases distribute 

 them that year to the young fish. Some of these parasites have to be 

 carried over the year before they can reinfect the fish. That is to say, 

 the fish will carry the parasite through the summer season, the parasite 

 sometimes reaching the adult condition in a couple of months or so ; 

 then they will produce their eggs, which pass out into the lower organ- 

 isms and there be carried over the winter. It is just a question, then, 

 of breaking up the life history of the parasite ; if we can do that at any 

 point we have got him. 



Mr. Titcomb: Do you think we could keep the ponds that are spr'ng 

 fed free from parasites for any definite period? 



Dr. Osburn: I think you could. Some of these lower organisms 

 can hibernate in the mud, or can encyst themselves and get through the 

 winter in that way, but a sudden draining off of the water would have 

 the effect of seriously interfering with this procedure. The result would 

 be that the next year you would start in free from that kind of organ- 

 ism carrying parasites. 



Mr. Titcomb: We have in Connecticut one small -mouth bass breed- 

 ing establishment that I am familiar with. There the water is supplied 

 to concrete pools used for breeding the dimensions of which are, I 

 should judge, about 10 feet by 30 feet. The bass are taken from the 

 private lake in the spring and reproduced in these lower pools; then 

 the fry are taken from the nests and put into these concrete pools. 

 The superintendent keeps two crews of men at work on the lake above 

 which is the source of water supply, two small power boats being en- 

 gaged in dragging for plankton. He feeds the little bass in the concrete 

 pools on plankton until they are about an inch and a half long. Some 

 years he has a very good production, and some years he loses 100,000 

 in a night from what he has called fungus. I happened to be there at 

 the time this sudden mortality occvu-red; he thought it was brought 

 about by something in the plankton. What would be your theory about 

 that? 



Dr. Osburn: I do not think there is anything in the plankton that 

 could ordinarily bring about that sort of loss. 



Mr. Titcomb: In that netting he would probably get the parasites 

 too, would he not? 



