104 Tzvciity-sc'vciith Annual Meeting 



inaw and Green Bay, and they are by far the most productive 

 areas. We get more fish in those parts of the lake than all the 

 rest of the lake; don't you think that temperature in a great meas- 

 ure accounts for it? 



Prof. Birge: I have no doubt that this has influence; but I 

 don't really feel that I know anything about the problems the 

 Great Lakes offer in regard to temperature. The shallow nature 

 of Lake Erie must permit the sun to warm it up; you get the 

 whole heat of the sun concentrated on the shallow water. While 

 the heat is projected to a slight depth only in Lake Michigan, it 

 produces a great deal of warmth in Lake Erie. 



Mr. Bower: Take the whole of Lake Erie west of a point 

 drawn across the lake from the east part of Sandusky Bay and 

 there is not a spot anywhere that exceeds 46 feet in depth. There 

 is a vast area there of a great many scjuare miles. 



Prof. Birge: The temperature at the top and bottom would 

 probably be about the same. 



3ilr. Bower: It would seem from your explanation that the 

 lake would be stirred from top to bottom. 



Mr. Gunckel : I don't think there is probably any question 

 that in the upper end of Lake Erie, the locality Mr. Bower has 

 •spoken of, that in the fall it is stirred from the action of the 

 waves and wind, from top to bottom. From the fact that in very 

 heavy winds when the whitefish are on. they are driven ofif when 

 these heavy winds occur, and it nnist be stirred from top to 

 bottom. 



Prof. Birge: I might say also, where you don't get the water 

 roiled, the wind has a great deal of efifect on temperature; take it 

 in Lake Mcndota, the wind does not stir the water up from the 

 top. There are horizontal currents which are moving around, 

 which must produce a great deal of effect on the temperature. 

 You will see in the diagram little irregularities in the tempera- 

 ture, which were, not to be accounted for by the warming of the 

 water. At 12 o'clock the temperature would be up a degree, and 

 at 3 o'clock it might be down, and at 6 o'clock it might be up. 

 We found continuously little fluctuations in the temperature 

 which could onlv be due to currents flowing more or less horizon- 

 tallv. 



Mr. Bower: I remember when I was a boy and used to 

 go in swinnning, we used to suddenly plunge into water that 



