346 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



over the 11-year period (88 pairs of percentages) was 0.70. For Lake Huron, where 

 intensive fishing frequently was carried on despite a low abundance of whitefish, the 

 coefficient of correlation between the percentages of fishing intensity and abundance 

 (66 pairs of percentages) was only 0.23. 



The statement that fishing intensity and production were better adjusted to the 

 abundance of whitefish in Lake Michigan than in Lake Huron applies to the data for 

 the entire lakes (table 22) as well as to the data for the individual districts. (Com- 

 pare also figs. 11 and 21.) In Lake Michigan the fishing intensity for whitefish was 



19 3 3 



C A L £ N D A ft 



Figure 21. — Annual fluctuations in the production (solid tine) and abundance (long dashes) of whitefish and in the intensity of the whitefish fishery 

 (short dashes) in Lake Michigan (all eight districts combined), 1920-1939. 



above average in every year in which the abundance was above average and was less 

 than average in 6 of the 7 years in which abundance was below average. Furthermore, 

 the intensity percentage exceeded the abundance percentage in 3 of the 4 years in which 

 abundance was above 100 but was less than the abundance percentage in 5 of the 7 

 years in which abundance was below 100. Every year in which the abundance of 

 whitefish was above average was a year of greater than average production; the catch 

 of whitefish was below average, however, in every year in which the abundance of the 

 species was below average. The production percentage exceeded the abundance per- 

 centage in every year in which abundance was above average, but the former was less 

 than the latter in 6 of the 7 years with abundance below average. 



Table 22. — Production and abundance of whitefish and the intensity of the whitefish fishery in the State of 



Michigan waters of Lakes Michigan and Huron 



[Expressed as percentages of the 1929-1939 average] 



Altogether different was the relationship of fishing intensity and production to the 

 abundance of whitefish in Lake Huron. In that lake the fishing intensity was above 

 average in 5 (exactly 100 percent in 1 year) of the 7 years in which abundance was 

 below average; furthermore, the intensity percentage exceeded the abundance percent- 

 age in every one of these 7 years. The catch also was disproportionately high in peri- 

 ods of low abundance. The catch percentage exceeded the abundance percentage in 



