DISSOLVED OXYGEN AS A FACTOR IN THE DISTRI¬ 
BUTION OF FISHES. 
CHANCEY JUDAY AND GEORGE WAGNER. 
[Biological Notes from t'be Laboratory of the Wisconsin Geological and Natural 
History Survey. III.] 
Lakes of various sizes and depths are numerous in the cen¬ 
tral portion of northern Wisconsin, and the good fishing for 
which some of them are noted attracts many anglers each sea¬ 
son. For the purpose of improving and diversifying the fish¬ 
ing, efforts have been made from time to time during the past 
few years to stock most of the lakes that are of any consider¬ 
able size and depth with the Great Lake or Mackinaw trout 
(Cristivomer namaycush). It has been found, however, that 
this trout does not thrive in many of the lakes in which it has 
been introduced; in fact, the efforts have met with success in 
only a very small number of cases. So many failures, of 
course, raised a query as to their cause. For the past two 
years, this Survey has been making a study of some lakes in 
central and southeastern Wisconsin with respect to the gases 
dissolved in their waters, and the results obtained for dissolved 
oxygen in some cases suggested that this gas might be a very 
important factor in the success or failure of the experiments 
with the Mackinaw trout in the northern lakes. Accordingly, 
early in September 1906, two of them, Kawaguesaga and 
Trout lakes, both located in the vicinity of Minocqua, were 
visited, and observations were made on them relative to the 
amount and distribution of the oxygen dissolved in their 
waters. 
2—s. & A. 
