324 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



these two northern districts the maximum productions were 263 and 317 percent, 

 respectively, of the 1929 yield. In central Lake Huron the maxima were 476 percent 

 in H-3 and 431 percent in H-4. It was in southern Lake Huron, however, that the 

 greatest relative increases in production occurred. The maximum yield was more than 

 26 times the 1929 catch in H-5 and more than 15 times the 1929 production in H-6. 



The differences in the relative maximum yields attained in the several districts 

 are to be attributed primarily to differences in the relative increases in fishing intensity. 

 The maximum intensity in H-l and H-2 was a little more than twice that of 1929. 

 It was roughly 5 times the 1929 level of intensity in H-3 and 4 times in H-4. In H-5 

 and H-6, however, the maximum fishing intensities were, respectively, 42 and 27 times 

 the 1929 intensity. 



The relative maximum abundance attained in the various districts exhibited re- 

 markable agreement. In four of the six districts (H-l, H^i, H-5, and H-6) the 

 maximum abundance was between 140 and 150 percent of the abundance in 1929, 

 and in a fifth (H-2) the maximum was a little less than 140 percent (136 percent) of 

 the 1929 level. In H-3 the greatest estimated abundance occurred in 1929 in which 

 year the pound nets were particularly successful (table 11). The abundance in H-3 

 fell in 1930 but increased in 1931; peculiarly enough the abundance in 1931 was 143 

 percent of that in 1930 (c/. increases in other districts over 1929 abundance). 



Production and abundance in 1939 were below the 1929 level in every district, 

 and the fishing intensity was less than that of 1929 in all but the two southernmost 

 districts. Of especial significance is the fact that the abundance in 1939 was rela- 

 tively much higher in H-l and H-2, the two districts in which production and 

 intensity had reached the relatively lowest maxima. In the remainder of the lake the 

 whitefish had almost disappeared. So great was the depletion that in H-5 and H-6 



Table 7. — Maximum and 1939 production and abundance of whitefish and maximum and 1939 fishing 

 intensity for ivhitefish expressed as percentages of the 1929 values in each statistical district of Lake 

 Huron 



1 The deep-trap-net fishery of 1929 was excluded in the compulations of these percentages of production and fishing intensity for H-2. 



— IOOO 



4 

 7 5 O * 



- 5 O i 



19 2 9 19 3 1 I 9 3 3 19 3 5 19 3 7 19 3 9 



CALENDAR r E A P 



Figure 5.— First district, H-l. 



Figures 5 to 10 show the annual fluctuations in the production (solid lines) and abundance (long dashes) of whitefish and in the intensity of 

 the whitefish fishery (short dashes) over the period, 1929-1939, in each of the six statistical districts of Lake Huron (see fig. 4). In each figure the 

 central horizontal line represents the average conditions for the 11 years. 1929-1939. 



