and in 1953 in 3 (M-2, M-7, M-8). Years of 

 minimum intensity ranged from 1929 in M-8 to 

 1951 in M- 4. For the combined districts the 

 maximum intensity of 240 in 1953 was 5.9 times 

 the minimum of 41 in 1943 and 1944 (data from 

 table 17). 



Despite certain disagreements and ex- 

 ceptions to trend, the fluctuations of fishing 

 intensity in the various districts exhibited 

 numerous similarities. The trend was down- 

 ward during the earlier years of the 1929-1953 

 period, and in both 1932 and 1933 intensity was 

 below the 1929-1943 average (usually by a wide 

 margin) in every district. Fishing intensity 

 increased in every district in 1934. It was above 

 the 15-year average in all 7 districts in 1935 and 

 1936 and in 5 or 6 districts in 1937-1939. A 

 general decline dropped intensity indices of all 

 districts below the 1929-1943 average in 1940 

 and with only 4 exceptions (M-8 in 1943; M-2 in 

 1945 and 1946; M-7 in 1946) they remained below 

 average through 1946. The next 7 years (1947- 

 1953) were a period ofgenerally intensive fishing 

 in all districts but M-3 and M-4. The index did 

 not reach the 15-year average in M-3 (highest 

 value, 74 in 1949) and in M-4 it was below aver- 

 age in all years but 1947 and 1949. In the 

 remaining districts only one index was below 

 average (M-5 in 1947) and some extremely high 

 levels were reached, especially in M-2 and M-8. 



The third presentation, based on records 

 of the expected catch, indicates fluctuations 

 within districts and also permits comparisons 

 between districts (table 17). The unit in the 

 table is an expected catch of 7, 620 pounds or 

 1/1 .500 of the total expected catch of all 8 

 districts over the 15-year base period 1929- 

 1943. (The expected catch in M-l each year 

 was estimated by dividing 1/100 of the average 

 abundance in districts M-2 through M-8 into the 

 actual production of M-l .) As a result of this 

 arrangement, the sum of the units for the dis- 

 tricts in a particular year provides an index of 

 fishing intensity in all State of Michigan waters, 

 expressed as a percentage of the 15 -year aver- 

 age. Furthermore, the 1929-1943 average 

 number of units for a single district is an estimate 

 of the percentage of the 15-year total intensity 

 exerted in the district. A peculiar feature of this 

 method of estimating intensity is the variation 



among the districts in the amount of fishing 

 pressure represented by a unit of gear. The 

 lift of 10, 000 feet of chub gill nets, represents 

 an expected catch equal to the 15 -year average 

 catch-per -unit effort in the district in which the 

 gear is lifted. As may be seen in table 9 this 

 figure ranged from 184 pounds in M-4 to 253 

 pounds in M-2. 



Since the fluctuations of fishing intensity 

 within individual districts were described from 

 tables 15 and 16, comments on table 17 are con- 

 cerned principally with between-district 

 comparisons. Fishing pressure was invariably 

 lightest in M-l, the district in which chub fish- 

 ing is so unimportant that records of gear are 

 not maintained . Some of the remaining 7 districts 

 tended to have relatively intensive and others 

 light fishing, but for all of them the annual rank- 

 ing varied widely (table 18). In 1929-1943, the 

 range of the ranks covered 5 or 6 positions in 

 every district but M-2 (range of 4- -fourth to 

 seventh). The 3 districts that shared first rank, 

 for example, also ranked as low as fifth (M-5, 

 M-7) or sixth (M-3). Similarly the 4 districts 

 which at some time held last position were in 

 other years as high as fourth (M-2), third (M-4) 

 or even second (M-6, M-8). Variations were 

 wide in 1944-1953 also. M-8, for example, had 

 a more intensive chub fishery than any other 

 district in 4 of the 10 years, but in 2 years was 

 in last place. The ranges were smaller in the 

 remaining districts but were never less than 4 

 positions (M-4, M-7) . 



The distribution of fishing intensity among 

 the districts changed notably from 1929-1943 to 

 1944-1953. In the 15 -year base period, fishing 

 intensity, on the average, was heaviest in M-3 

 (20.7 percent of total) and M-5 (20.6 percent) 

 followed by M-7 (17.4 percent) and M-6 (15.9 

 percent) . The remaining three districts were 

 all under 10 percent. In 1944-1953 the centers 

 of most intensive fishing had shifted to M-2 and 

 M-8 . The former district accounted for 21.6 

 percent of the 1944-1953 intensity and was in 

 first position as contrasted to sixth in 1929-1943. 

 At the same time M-8 increased its percentage 

 from 9.6 to 19.8 and its rank from fifth to second. 

 Greatest decrease occurred in M-3 which dropped 

 from first to sixth position and suffered a per- 

 centage loss from 20.7 to 6.5. The re la t ive 



38 



