the fisheries and sometimes against his wishes, 

 used one or more small -mesh nets in their gang 

 through the entire fall fishing season. 



The total lifts during each fishing season 

 were divided by the number of fishermen to de- 

 termine the average number of lifts per 

 fisherman (table 6). 



Ordinarily the abundance of walleyes and 

 the condition of the market controlled the length 

 of the summer season and the number of lifts 

 made. When walleyes were abundant and the 

 quota was easily reached, the season was short- 

 ened and consequently the number of lifts 

 reduced, unless market conditions necessitated 

 interrupted fishing, when the season was pro- 

 longed but the number of lifts was not increased. 

 Table 6 shows there was a direct relation be- 

 tween length of season and number of lifts and 

 these serve, therefore, as rough indices of 

 abundance of walleyes . On this basis we would 

 conclude that 1930, 1931, 1932, 1937, and 1938 

 were good years and that 1933, 1934, 1935, and 

 particularly 1936 were poor years. This con- 

 clusion agrees with results obtained from 

 calculation of average catch per lift except for 

 the years 1930 and 1933. The close correspond- 

 ence of the results based on two different methods 

 strengthens the validity of our final conclusions 

 on relative abundance of walleyes in different 

 years . 



Although the length of the season and the 

 number of lifts usually depended on the abundance 

 of the fish, there is not necessarily any direct 

 relation between these two factors and the total 

 yield. The seasons may be relatively short and 

 the number of lifts below average but the total 

 catch of walleyes (table 5) may be comparatively 

 large (1931, 1937, 1938); or the reverse may be 

 true (1935, 1936). A direct relationship did ex- 

 ist, however, between length of season or number 

 of lifts and annual yield in 1930, 1932, 1933, and 

 1934. 



The large variation in average number of 

 fall lifts probably was related to weather condi- 

 tions and possibly also to abundance of fish. 

 During some years the lakes froze before the 

 peak of the whitefish spawning run occurred. K 

 whitefish were numerous and the run occurred 

 before the onset of freezing weather, then the 



desired quantity of eggs for artificial propaga - 

 tion could be secured with a smaller number of 

 lifts and in a shorter time than if whitefish were 

 scarce. 



Average catch per lift 



Statistics of the annual total yield of the 

 Red Lakes fisheries cannot be employed to 

 measure fluctuations in natural abundance of the 

 principal species because of the controlled maxi- 

 mum production and limitations as to the number 

 of lifts imposed by favorable or unfavorable 

 condition of the wholesale market. Since all 

 lifts presumably consisted of approximately the 

 same quantity of gear, the average catch per 

 lift is an approximate measure of the yield per 

 unit of fishing effort. The total catch of each 

 species during the summer seasons of 1930 to 

 1938 (table 5) was divided by the total number of 

 summer lifts (table 6) to obtain the catch per 

 lift (table 7). Catches and numbers of lifts dur- 

 ing the fall seasons are unsuited for analysis in 

 terms of catch per lift because of the mixture of 

 small -mesh nets and large -mesh nets employed 

 during that season. 



The 9 -year (1930-1938) mean of the 

 average summer catches of all fishermen was 

 122 pounds per lift (table 7) distributed accord- 

 ing to species as follows: walleye, 78; yellow 

 perch, 26; whitefish, 2; northern pike, 2; 

 freshwater drum, 3; goldeyes, 10; sucKers, 0.2; 

 and bullheads, 0.1. 



If the average catch per lift for the 9- 

 year interval is assumed to have an index value 

 of 100 (or 100 percent), then the annual fluctua- 

 tions in the abundance of all species and of the 

 individual species may be estimated by express- 

 ing the catch per lift in each year as a percentage 

 of the corresponding 9 -year mean. For example, 

 the catch per lift of all species combined in 1930 

 85.2 



was 100 X 



122 



or 70 percent of the 1930-1938 



average; similarly the "abundance percentage" 



for walleyes in the same year was 100 x ^ ~ 78. 

 Table 8 contains no computations of abunaaiKie 

 percentages for goldeyes, suckers, and bull- 

 heads . Data for the last two species were scanty 

 and fluctuations in the catch per lift of goldeyes 

 are believed to be unreliable as measures 



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