326 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



whitefish occurred in the four districts in which the use of the deep trap net led to an 

 excessive multiplication of fishing intensity and catch. The decline in the abundance 

 of whitefish was much less severe in the two districts in which the exploitation of the 

 stock was more moderate. Further evidence on the harmful effects of deep-trap-net 

 operations will be brought out by a more detailed consideration of the annual changes 

 in production, fishing intensity, and abundance in the various districts with reference to 

 the 1929-1939 averages. 



19 3 3 19 3 5 



CALENDAR V E A R 



Figure 8. — Fourth district, H-4. 



-12 5 



l O O ^ 



* 



7 5 t- 



o 



5 0^ 



19 3 3 19 3 5 



CALENDAR YEAR 



Figure 9. — Fifth district, H-5. 



