American Fisheries Society. 31 



Chairman Whitaker: Then their condition chd not show that 

 it was from the effect of starvation? They had not gotten into 

 this barren zone of water in the bottom and starved to death? 



Professor Birge: No, I saw no reason to beUeve that. The 

 fish were reasonably fat, and food was in their stomachs. 



Mr. Clark: Were any other fish affected besides the perch? 



Professor Birge: The whitefish also. They die every year 

 in certain numbers. I have never been able to get hold of a 

 dying whitefish to see whether its gills show the same symptoms. 

 Many more died this year than ever before. 



Chairman Whitaker: Have there been any recent physical 

 changes in the character of the lake? 



Professor Birge: No. 



Chairman Whitaker: Have there been any artificial changes 

 that would tend to contaminate the water at all? 



Professor Birge: No. At that time, I think, there was no 

 sewerage discharged into the lake, and the lake, except for hav- 

 ing a border of inhabitants, was in the same condition it had 

 been since the dam was put in there 30 or 40 years ago. 



Chairman Whitaker: Has this great mortality been of fre- 

 quent occurrence? 



Professor Birge: Never before, never since. 



Mr. Nevin: Last year in Barron County, Wis., the white- 

 fish died in great numbers. 



Professor Birge: Those epidemics are only occasional. We 

 do not often get a chance to study them, and it seems to me it 

 would be well worth while, if one could get an opportunity to 

 study it with reference to the condition of die bottom water of 

 the lake, to see whether, under some exceptional conditions the 

 bottom of the lake does not get exceptionally foul and thus 

 accumulate poisonous material which may cause directly the 

 death of these fish. I ought to add, however, that the Mendota 

 epidemic ceased about the middle of August, A\hile the lower 

 water must have been still foul. 



Mr. Clark: You did not examine to see if it affected the 

 animalcules of the lake? 



Professor Birge: At that time 1 was not studying them, but 

 it is quite evident that the Crustacea do not live in that water. The 



