States of Illinois, 1950-1953, and Wis - 

 consin, 1953 . --Because of the limited number 

 of years of record, statistics on fishing intensity 

 in Illinois and Wisconsin are given only in terms 

 of the number of Lifts of 10, 000 -foot units of gill 

 nets. The lifts in Illinois (table 13) ranged from 

 1, 795 in 1952 to an estimated (see footnote to 

 table) 2, 317 in 1950. Fishing intensity was 

 greater in Illinois in 1950 and 1951 than in the 

 larger adjacent Michigan district M-8 (table 14), 

 but was less in 1952 and 1953. The 1953 intensity 

 of 2, 036 units in Illinois was 1 .74 times that in 

 the small Wisconsin district, W-6, immediately 

 to the north (table 7- -see also fig. 2). 



The 1953 fishing intensity in Wisconsin 

 districts W-l and W-2 was inconsequential but 

 pressure was heavy in districts W-3 through 

 W-6, especially in W-4 and W-5 where the num- 

 bers of units lifted were 5, 093 and 5, 323, 

 respectively. How greatly the fishing pressure 

 on the west side of Lake Michigan exceeded that 

 on the east is brought out by the following tabula- 

 tion of the numbers of units of small-mesh gill 

 nets lifted (Green Bay districts omitted): 



The production records of earlier years (table 2) 

 suggest that in the past as well as in 1953, fish- 

 ing intensity was much the greater on the western 

 side of Lake Michigan. 



Summary 



The chub fishery of Lake Michigan has 

 been based on 7 species of the subgenus 

 Leucichthys of the genus Coregonus . The species 

 composition of the catch has exhibited long-term 

 trends and also varies seasonally. Largely be- 

 cause of inadequate taxonomy and local variation 

 of common names, part or all of the earlier pro- 

 duction of chubs was combined in the statistics 

 with catches of such other species as whitefish 

 and lake herring. Usable statistics of production 



begin with 1926. Figures for earlier years serve 

 principally to show that an active fishery for 

 chubs existed back into the 1890' s and that the 

 take in some years ran to several million pounds. 



The catch of chubs in Lake Michigan 

 (4 states combined) in 1926-1953 ranged from 

 1, 630, 000 pounds in 1941 to 11, 151, 000 pounds 

 in 1953 . The production increased annually over 

 the 1941-1953 period. The 1926-1953 average 

 was 5,135,000 pounds. Of this amount Wisconsin 

 contributed 60.3 percent; Michigan, 24.8 per- 

 cent; Illinois, 12.7 percent; and Indiana, 2.2 

 percent. Catches listed for Indiana were made 

 mostly or entirely in State of Michigan waters. 



Records of catch are available for the 8 

 statistical districts (M-l through M-8--see fig. 2 

 for boundaries of districts) of the State of Michi- 

 gan in 1929-1953. The production of chubs has 

 always been insignificant in M-l (Green Bay). 

 The annual take varied widely in the remaining 

 7 districts but it exceeded 400, 000 pounds in at 

 least one year in each of them but the small dis- 

 trict M-4. Centers of major production shifted 

 from 1929-1943 to 1944-1953. In the former 

 period the only districts that contributed more 

 than 20 percent of the total catch were M-3 and 

 M-5. In 1944-1953 the catch amounted to 20 per- 

 cent or more of the total in M-2, M-7, and M-8 . 



Records of chub production in Wisconsin 

 districts (W-l through W-6) are at hand for 1953 

 only. (Reports back through 1936 remain to be 

 analyzed.) Here as in Michigan the Green Bay 

 catch (W-l and W-2) was unimportant but the take 

 was heavy in the main -lake districts --from 

 592, 000 pounds in the relatively small district 

 W-6 to 2, 235, 000 pounds in W-5. Illinois and 

 Indiana waters are not divided into statistical 

 districts . 



The use of data on catch per unit effort 

 to estimate fluctuations in the abundance or avail- 

 ability of chubs is handicapped by bias from the 

 following sources: changes in the regulations on 

 the minimum legal mesh size of smalJ-mesh gill 

 nets (the principal gear of capture of chubs); varia- 

 tion in the enforcement of the laws; changes in the 

 efficiency of twine from which the nets are con- 

 structed. Possible effects of these factors are 

 discussed and records of fluctuations in abundance 



43 



