Therefore, a comparison has been made of the 

 seasonal averages for 11 localities, each of 

 which was sampled in both winters. These 11 

 localities are the ones listed for both winters in 

 table 16, except for the omission of Winter 

 Creek. This comparison yields the following 

 figures: the mean for 1944-45 is 0.46; the mean 

 for 1945-46 is 0.39 fish per hour. The value of 

 d/rfj is 0.9. This is not of statistical signific- 

 ance; and hence it cannot be proved mathematic- 

 ally that the fishing in these localities was 

 better in one of the two winters than in the other . 



The week-to-week averages for fishing 

 success for pool 8 in the summers 1944 and 

 1945 are shown in figure 6. The individual 

 weekly fluctuations in these two curves are large. 



The over -all averages for fishing success 

 for the two summer censuses are 0.71 fish per 

 hour for 1944 and 0.50 for 1945. However, since 

 the territory involved was of much greater ex- 

 tent in 1945, the difference between the two 

 mean values has little meaning. From only 3 

 localities were adequate samples taken in both 

 summers (Dresbach Dam, Onalaska Spillway, 

 and Black River, all in pool 8). The over -all 

 seasonal mean for the total of these 3 localities 

 was 0.63 fish per hour in 1944 and 0.41 in 1945. 

 A comparison of these two means by the method 

 of comparing small samples yields a value of ^ 

 equal to 1.5 (for which P is somewhat larger 

 than 0.1). The statistical significance therefore 

 is doubtful and it cannot be considered as proven 

 that the fishing in this section of the Mississippi 

 River was better in the summer of 1944 than 

 1945. 



Influence of certain factors 



Fishing pressure. Several authors have attempt- 

 ed to show a relationship of the fishing success 

 with the intensity of fishing. Eschmeyer (1942) 

 stated that in Norris Reservoir, Tennessee, the 

 fishing intensity increased for several consecu- 

 tive seasons without any appreciable decline in 

 catch per hour . In other words, the total take 

 increased. However, in another water (Fife 

 Lake, Michigan), the same author (Eschmeyer, 

 1939) found the catch per hour to decline through 

 4 seasons, as the fishing intensity increased. 

 Thus he reasoned that the lake, which was fairly 



heavily fished, had about a constant available 

 crop from one year to the next. 



On the Upper Mississippi River, on the 

 whole it is probable that the fishing pressure 

 has little or no influence upon the catch. The 

 available crop remains large in relation to the 

 annual harvest. At certain places and times, 

 however, the fishing intensity may have a tempor- 

 ary effect. Especially is this true of certain 

 fishing spots where the fishing is concentrated 

 at the beginning of winter . An area of only a 

 few acres may be worked by scores of fisher- 

 men day after day if the fish happen to be biting 

 well. In the winter the fish are not moving so 

 much as in the summer, presumably; and what 

 was the catchable population of a small slough 

 or backwater at the onset of ice cover may be- 

 come fished out in a few days or weeks, result- 

 ing in poorer fishing for the remainder of the 

 winter. 



Eschmeyer (1942) believgd that the de- 

 cline in the fishing success in Norris Reservoir, 

 after June may have been due largely to the re- 

 moval of large numbers of fish early in the 

 season. Also in Fife Lake, the same author 

 (Eschmeyer, 1939) attributed the poor fishing in 

 the late summer partly to the early-summer re- 

 moval of a considerable proportion of the avail- 

 able crop of fish; the remainder found food more 

 available . 



Bait. Table 19 shows the fishing success for 

 each of the 4 seasons according to the type of 

 bait used. There is of necessity some lumping 

 of data in this table. For instance, quite common- 

 ly a fisherman or a fishing party used both worms 

 and minnows on the same day, and in these cases 

 no attempt was made in the censusing to list 

 separately the amount of fishing effort and number 

 of fish caught for each of the two types of bait. 

 Therefore, a category had to be set up labeled 

 "worms and minnows" . Also, the classification 

 "other natural bait" lumps a wide variety (liter- 

 ally dozens of kinds) of baits, ranging from frogs 

 to doug^ -halls. Because of the relatively small 

 amount of fishing done with any one type of 

 artificial bait, such as plugs, spinners, flies, 

 etc . , all of these are placed together in one 

 category . 



35 



