Biological Survey — Erie-Niagara Watershed 101 



Fish seeking the cold water in summer apparently follow the 

 bottom layer as it penetrates new areas. Fishermen at Port 

 Dover complained that this summer they had found the fish widely 

 dispersed and were forced to set their nets over a much greater 

 area than usual. This would indicate that during the seasons 

 when the lake warms more gradually than usual the cold bottom 

 water is limited to a relatively small area. The summer heating 

 of the present season was rapid, and the surface layer rapidly 

 reaching a high temperature resulted in a stratification of the 

 water mass, thus preventing vertical mixing. This fact was 

 further indicated in the case of storms. Summer storms were 

 found to penetrate to the bottom only in shallow depths. In 

 greater depths during the past season they did not reach below 

 the thermocline. During the bad wind storms of late August and 

 early September the bottom water remained unchanged. Even 

 at the shallower stations the bottom temperatures were unaffected 

 and the plankton of the lower levels remained stratified in its 

 usual manner, although the slightest churning, as for instance 

 in the Emerald channel where the lake empties into the Niagara 

 river, is sufficient to distribute it throughout the water mass. 

 Everywhere else it was found even during the worst storms con- 

 centrated during the day near the bottom. Thus we may conclude 

 that except in shallow water storms probably do not destroy eggs 

 and helpless fry. During the Avinter months a coating of ice keeps 

 the water mass intact and protects the incubating eggs of the 

 whitefish and herring and during the summer the warm light sur- 

 face water acts in a similar capacity. In years when the ice is 

 particularly late in forming and the winds are unusually severe 

 it is possible that large numbers of the eggs of fall spawning 

 fishes in shallow water may be destroyed. It is not improbable 

 that further investigations may show that the fluctuations in year 

 classes may be found to be at least partially explainable on 

 this basis, although the very poor production years more likely 

 result from a combination of factors. However, the decline in 

 the fish supply of Lake Erie cannot be attributed to storms, for 

 the weather of the present day is no more severe than that of 

 former times when the lake abounded with fish. 



Subsurface currents of considerable force were found, not 

 always corresponding to those at the surface. Following storms 

 or barometric irregularities the lake level readjusts itself and in 

 doing this subsurface currents are formed. In eighteen hours in 

 the deep hole the current in the intermediate levels showed a 

 wide fluctuation in rate and direction. It may be that the damage 

 to the fishing gear in deep water is caused by these movements. 

 However violent in force there is not the churning action found 

 in surface water, and, although no doubt an important factor in 

 transporting eggs and young fry from one place to another, they 

 probably exert little or no destructive action. 



Bacteriology and Chemistry. — As a result of the analyses made 

 by the Buffalo City Chemist and Bacteriologist from samples taken 



