340 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



conditions in the single year, 1929. The figures for this year were taken as the most 

 nearly "normal" data available (p. 323). The computation of the above percentages for 

 Lake Michigan also with respect to 1929 conditions would not have been valid because 

 production, abundance, and almost certainly fishing intensity, as well, were above 

 normal in Lake Michigan in that year. On the other hand, the data for the period, 

 1929-1939, were not greatly, if at all, distorted by the deep-trap-net fishery in Lake 

 Michigan. Furthermore, these 11 years included periods of high, moderate, and low 

 production and apparently also periods of high, moderate, and low abundance and 

 fishing intensity. Consequently, the 11-year averages have been taken as the most 

 nearly normal bases available for the estimation of the maximum and 1939 percent- 

 ages of production, fishing intensity, and abundance for the Lake Michigan whitefish. 

 It is believed that this variation of procedure has made the data of tables 7 and 18 as 

 nearly comparable as is possible. 



In comparison with Lake Huron the maxima of yields in Lake Michigan were 

 relatively small. The maximum exceeded 3 times the assume'd normal in only two 

 districts (433 percent in M-7 and 345 percent in M-6). Of the remaining six dis- 

 tricts the maximum production was greater than twice the normal in three (M-l, M-3, 

 and M-8), was between IV2 and 2 times the normal in two (M-2 and M-5), and was 

 less than 1^ times the normal in one (M-4). In Lake Huron, on the contrary, the 

 relatively lowest maximum yield was 263 percent of the 1929 catch (H-l) and the 

 maxima in the remaining districts ranged from 317 in H-2 to as high as 2,662 in H-5. 

 This comparison lends additional strong support to the belief that the use of the deep 

 trap net brought about an excessive increase in yield in Lake Huron, especially in 

 the four southern districts. 



The maxima of fishing intensity were relatively lower in Lake Michigan than were 

 the maxima of production. The peak fishing intensity was more than twice the normal 

 only in southern Lake Michigan (M-6, M-7, and M-8). The five remaining percent- 

 ages were all below 200, and two of them (M^t and M-5) were less than 150. In 

 Lake Huron the maximum percentage was more than twice the normal in every district; 

 in the four southerly districts the maxima ranged from roughly 4 to 42 times the normal. 

 Again the comparison of data for Lake Michigan and Lake Huron supports the earlier 

 conclusion, namely, that the deep-trap-net operations led to an abnormally increased 

 fishing intensity in Lake Huron with the increase greatest in the central and southern 

 regions of the lake. 



The maxima of abundance of whitefish were relatively higher in Lake Michigan 

 than in Lake Huron. In two districts the percentages exceeded 200 (M-6 and M-7) ; 

 of the remaining six districts the percentages were above 150 in five and below 150 in 

 only one. The corresponding percentages for Lake Huron were all below 150. These 

 low values of the maximum abundance of whitefish in Lake Huron suggest the possibility 

 that abundance in 1929, the year taken as normal, may have been somewhat above 

 normal as well as above the Lake Huron average for 1929-1939. An alternative explan- 

 ation is offered by the possibility that, in some districts at least, a higher maximum 

 abundance might have been attained if fishing intensity and production had been less. 



The estimates of the 1939 conditions in Lakes Michigan and Huron in relation to 

 the assumed "normals" for the lakes provide further striking comparisons. Production 

 was at a low level in both lakes in 1939. In Lake Michigan, however, only two dis- 

 tricts of eight had yields below 20 percent of normal, whereas in Lake Huron three of 

 the six districts were below that level. Three of the Lake Michigan districts had per- 

 centages of 40 or above; in Lake Huron the only production greater than 40 percent 

 o£ normal (46 in H-6) was made possible by reason of a fishing intensity that was 

 more than 4 times the normal. 



Fishing intensities in 1939 were generally relatively lower in Lake Michigan than 

 in Lake Huron. In five of six districts of Lake Huron the intensity of the fishery for 

 whitefish was 50 percent or more of the 1929 "normal"; in 2 districts (H-5 and H-6) 

 the intensity in 1939 was more than 4 times the normal. The intensity of the white- 

 fish fishery in Lake Michigan was above 50 percent of normal in only four of eight 

 districts and was only 88 percent in M-4, the district with the most intensive fishery. 



