DECLINE OF LAKE TROUT IN LAKE MICHIGAN 



85 



the 9 "high-production" years listed in tabic 8 

 for the first three districts, 8 were earlier than 1940 

 (the 1941 production in M-2 provided the only 

 exception) and 5 earlier than 1935. In districts 

 M— i through M-8, on the contrary, the highest 



yields usually came after 1939. Only 2 of the 15 

 high-production years listed for the southern dis- 

 tricts were earlier than 1940 (1932 in M-6 and 

 M-7) and 10 fell within the brief 4-year period 

 1941^4. 



O 



z 



3 

 O 



0. 



CO 



a 



< 



o 

 o 



200 



— 100 



M 

 O 



< 



Ul 



> 

 < 





1990 



I93S 



1940 



1945 





Z 500 



o 



o 

 o 



ce 

 a 



400 



300 



200 



100 



M-2 



200 



ti. 



o 



lil 

 o 



< 

 I- 

 z 



u 



too 



1930 



1935 



1940 



1945 



FlGtTBE 3. — Production, abundance index, and fishing-intensity index for lake trout in districts M-l and M-2 1929-49. 

 Solid line = production ; long dashes = abundance index ; short dashes= fishing-intensity index. Scale at left (thousands 

 of pounds) appUes only to production; scale at right is in terms of 1929-43 mean for each item. 



