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Figure 12.— Comparison of size of 1-annulus smolts in 1957 from Little Kitoi Lake (upper) and Ruth Lake (lower)- 



1955 brood year. 



TROPHIC CONDITIONS IN THE LAKES 



Trophic conditions in lakes have a strong 

 influence on the well-being of young salmon 

 (Foerster, 1925). To ensure the greatest pro- 

 duction, lakes with sufficient and proper food 

 should be chosen for rearing areas. Analysis 

 of the stomach contents of sockeye yearlings 

 in Cultus Lake showed Cyclops to be the 

 major food, followed in order of importance 

 by Daphnia , Bosmina, and to a much lesser 

 extent by Epischura. Insects were minor food 

 items. In most lakes of the Fraser River 

 system, cladocerans and copepods were the 



principal food. In the Stuart Lake district, 

 primarily insects were taken (particularly 

 Tendipedidae); some cladocerans were eaten 

 also. 



Although my data are not extensive, the 

 available information on plankton, periphyton, 

 and bottom fauna supports the view that 

 trophic conditions influence the survival, 

 growth, and condition of sockeye in the lakes 

 under study. 



Samples from Little Kitoi Lake, Ruth Lake, 

 and other lakes near Kitoi Bay, taken before 

 Ruth Lake was treated, indicated that all of 

 the lakes had about the same low level of 



15 



