only two minor irregularities (1946 and 1950) 

 to a maximum of 3, 546, 000 pounds (454 per- 

 cent of the 1929-1943 mean) in 1953. The trend 

 during the 1941-1953 interval was irregularly 

 upward in all 7 chub-producing districts, but 

 in M-3 it was too weak to carry the take to the 

 15-year base level and in M-4 the catch exceed- 

 ed the 1929-1943 average only 3 times (1947, 

 1949, and 1953). The increase in the catch was 

 large in M-5 but the highest take (in 1952) of 

 recent years was still below the 1935 figure. 

 New production records were set in the remain- 

 ing 4 districts. Highest levels were reached in 

 M-8 where the 1953 catch of 1, 083, 000 pounds 

 was 14-1/2 times the 15-year mean and in M-2 

 where the 1952 take was 11-1/2 times the 1929- 

 1943 figure. Maxima attained in the remaining 

 2 districts were 790, 000 pounds (608 percent 

 of average) in M-7 in 1953 and 490, 000 pounds 

 (430 percent of average in M-6 in 1950. 



Differences among the districts as to the 

 extent of recent increases in chub production- - 

 especially the high levels reached in M-2 and 

 M-8 and the failure of production in M-3 even 

 to attain the base-period mean- -led to con- 

 siderable changes from 1929-1943 to 1944-1953 

 in the percentage distribution of the catch 

 (table 6) . Greatest improvement of relative 

 importance occurred in M-8 which moved from 

 fifth to second position and had a percentage in 

 1944-1953 that was 2.31 times that of 1929-1943. 

 Improvement was nearly the same in M-2 which 

 advanced from sixth to third and had a ratio of 

 2 .30 for the two percentages . M-7 changed 

 from third to first position but the percentage 

 for 1944-1953 was only 1.36 times that for 1929- 

 1943. M-6 and M-4 held fourth and seventh 

 rank, respectively, in both periods . The per- 

 centage contribution of M-6 changed little 

 (ratio of 0.99) but that of M-4 declined severely 

 (ratio of 0.29). Major loss of relative import- 

 ance in chub production took place in M-3 which 

 dropped from second to sixth position and had a 

 1944-1953 percentage only 0.21 of that of 1929- 

 1943 . M-5 also suffered a large drop in rank 

 (from 1 to 5) but experienced a relatively modest 

 decline in percentage (ratio, 0.63). 



7/ Even this small catch included relatively few 

 bona fide chubs; a large proportion was made up 

 of fat lake herring. 



State of Wisconsin, 1953 . --Records of 

 the 1953 production of chubs in Wisconsin dis- 

 tricts (fig. 2 and table 7--statistics on fishing 

 effort and catch per unit of effort are discussed 

 in later sections) show that here as in Michigan 

 almost the entire take comes from Lake Michi- 

 gan proper. The two Green Bay districts (W-l 

 and W-2) accounted for little more than 1 per- 

 cent of the total catch.- Among the remaining 

 districts the catches fell in the order, W-5, W-4, 

 W-3, and W-6 (last district of limited area) . 

 If allowance is made for the small size of W-6, 

 it may be stated that Wisconsin districts were 

 far more productive than the adjacent Michigan 

 waters. 



Abundance of chubs in Lake Michigan, 

 1929-1953 



Attempts to trace fluctuations in the 

 abundance of chubs from records of the catch- 

 per -unit -effort of the small-mesh gill nets, 

 which take the great bulk of the production, are 

 handicapped by changes in laws on the construc- 

 tion (especially mesh size) of the nets, variation 

 in the enforcement of those laws, and changes 

 in the type of twine from which the nets are 

 made. The laws relating to chub nets are, of 

 course, a matter of readily accessible record. 

 In Michigan, the state for which we have the most 

 extensive statistics on catch per unit effort 

 (1929-1953), the minimum legal mesh size for 

 chub gill nets was 2-3/4 inches, stretched 

 measure?.' (actually the legal mesh size was 

 2-3/4 to 2-7/8 inches, but only the minimum 

 need be considered here). In 1933 the mesh 

 size for chub gill nets was reduced to 2-5/8 

 inches, stretched measure, and in 1939 the legal 



8/A stiff steel rule with a notch in the side at a 

 distance fromtSae end corresponding to the mini- 

 mum legal mesh size was used for gaging the 

 nets . The end of the rule was placed in the mesh; 

 if the mesh could then be fitted into the notch 

 without breaking the twine or slipping the knot, 

 that mesh was legal. (State laws include stipula- 

 tions on the location of meshes to be gaged and on 

 the number that must be measured to determine 

 the legal status of a net.) Flexible twine can be 

 stretched so much with this method of measure- 

 ment that the mesh sizes of gill nets as actually 

 fished are far below the stipulated legal minimum. 



23 



