This year great quantities of valuable fish were lost in deep lakes where 

 ihey had never died in that way before. The varieties affected chiefly were 

 the whitefishes, the loss being extremely heavy on tuUibee or mongrel 

 whitefish, and there was some loss of pike perch ; also in the Mille Lacs 

 some of the pickerels and other varieties were lost, but chiefly the deep 

 water fishes were affected. The men who made the investigation in Mille 

 Lacs this year estimated that towards the close of the period of mortality 

 there were at least 650,000 pounds of dead fish around the shoi-es of the 

 lake, which means that several million pounds of fish have died in that one 

 lake this summer. Professor Riley, of our State University, formerly of 

 Cornell, is studying the question to find out, if possible, whether any of 

 this mortality is due to parasitical infection. 



Mb. W. E. Barber, Madison, Wis. : Conditions in Wisconsin have not 

 been as bad as in Minnesota, but we found that in our deep water lakes 

 there was less mortality among the fishes than in the shallow lakes. In 

 various sections of the State the fish were dying, and we did not know 

 what was the cause. Professor Wagner, biologist at the University, made 

 some very extensive investigations and stated that the excessive heat and 

 lack of wind to aerate the water caused the death of the fishes. 



The lake in Wisconsin referred to by Mr. Avery is Lake Monona, and 

 pollution is the chief cause of its fish mortality. Sewage from Madison 

 drains into it, and causes a tremendous growth of vegetation, also a heavy 

 scum and green slime on the top of the water during the summer months ; 

 the stench is so bad as to cause complaint in almost every section when 

 the wind comes from the direction of the lake. The city had to make better 

 arrangements for the disposal of its sewage. 



But I think there is no remedy for the loss of fish in the ordinary lake 

 when we have extraordinary seasons of excessive heat, such as this 

 summer. It always has occurred and always will occur, and the wonder 

 of it is, when we realize the tremendous loss of fish through such conditions 

 as we have had this summer and the heavy coating of ice and snow in the 

 winter, that there are any fish left. Of course, these fish multiply rapidly 

 and we have fish in most of our lakes notwithstanding these conditions. 



Dr. E. E. Prince, Ottawa, Canada : Mr. Barber's statements are con- 

 firmed by what we have found in some lakes in Canada, very far from any 

 settlements under perfectly virgin conditions. That is to say, the depth 

 of the lake does not seem to have any relation to the serious loss of fish. I 

 happened to be on a remote lake in Canada a year or two ago, a lake 

 practically only visited by Indians and fur trappers, although there are 

 some small settlements at the west end. It is a very shallow lake and 

 covers 480 square miles. At times there is a tremendous destruction of fish. 

 You find whitefish and yellow perch and various other fishes lying dead 

 in windrows. It seems to be due to the unicellular alga (Tetragonium) 

 which grows luxuriously in certain seasons and then decays, poisoning the 

 water and creating an offensive odor. I mention this because Mr. Avery 

 referred to the depth and stagnation as having had something to do witl* 

 the death of the fish ; but when you find lakes which ai-e very shallow, like 

 the Lesser Slave Lake, and distant from any population, it is perfectly 

 clear that it is due to some cause such as I have mentioned. 



Mr. E. Lee LeCompte, Baltimore, Md. : The conditions in Maryland 



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