DECLINE OF LAKE TROUT IN LAKE MICHIGAN 



81 



PRODUCTION IN STATE OF MICHIGAN 

 WATERS, 1891-1908 AND 1929-49 



Records of the annual take of lake trout in the 

 several statistical districts * of the State of 

 Michigan in 1891-1 90S (table 3) make possible 

 the comparison of the actual productivity of 

 various regions and of their percentage contri- 

 butions to the total for the lake * in that period 



Table 3. — Production of lake troul in Michigan statistical 

 districts, 1891-1908 

 [In thousands of pounds] 



Table 4. — Production of lake trout in Michigan statistical 



districts, 1929-49 



[In thousands of pounds] 



with conditions in recent years (table 4). Despite 

 the considerable fluctuations in annual yield in 

 the different districts to be seen in table 3, com- 

 ments on the 1891-1908 data* will be restricted 

 to the averages; we are without the information on 

 fluctuations in the availability of lake trout, in 

 the intensity of the fishery, and in other conditions, 

 that we need for an intelligent treatment of the 

 matter. Attention should be called, however, to 

 the distinct similarity of trends in production in 

 the several districts. 



District M-3 strongly dominated the production 

 of lake trout in the State of ^lichigan waters of 

 Lake Michigan in 1891-1908, contributing 43.8 

 percent of the total output for the period. The 

 percentages for five of the seven remaining districts 

 e.xhibited only small differences, ranging from 10.3 

 percent for M-2 which held second position to 8.4 

 percent for M-7 which ranked sixth. The lowest 

 average yields were in M-1 (6.2 percent) and M-4 

 (3.2 percent). In this early period, waters north 

 of Grand Traverse Point (M-1, M-2, and M-3) ac- 

 coimted for 60.3 percent of the total output as 

 compared with 39.7 percent for districts M-4 

 through M-8. 



To facilitate comparisons between the produc- 

 tion of lake trout in the statistical districts in 

 1891-1908 (table 3) and 1929-43, the"base period" 

 for modern statistics (table 4), a summary (table 

 5) has been prepared. The principal features of the 

 comparison are a generally lower level of take in the 

 more recent period, a shifting of production toward 

 the more southerly districts, and a lack of pro- 

 noimced changes in the ranking of the districts 

 with respect to the percentage of total yield. 



Only M-5 exhibited a rise in average armual 

 production from 1891-1908 to 1929-13 (an increase 

 of 53,000 pounds). The remaining seven districts 

 all suffered declines that ranged from 7,000 pounds 

 in M-4 to the tremendous drop of 665,000 pounds 

 in M-3. This latter decline accounted for most of 

 the decrease of 885,000 poimds for the combined 

 districts. In no other district did the take fall by 

 more than 86,000 pounds (the decrease for M-2). 



1 Percentage of 1929-43 mean. 



' See figure 2 for the boundaries of the statistical districts. 

 ' The term "lake" in this and the following sections has reference to State 

 of Michigan waters only. 



• The data for 1891-1908 provide a less reliable record of production in the 

 individual districts than do those for 1929 and later. In the earlier period 

 the annual catch of each fisherman was allocated to the district in which his 

 home port was located, whereas in the recent period each day's catch was 

 credited to the statistical district in which the gear actually was lifted. The 

 extent to which fishermen operated outside their home districts in 1891-1908 

 is unlmown, but records for recent years suggest that error from this source 

 was not sufficiently great to affect the validity of comparisons based on tables 

 3 and 4, 



