fishermen participated in the summer fishery 

 each year and 174 in the fall fishery, and 223 

 fishermen took part at some time during the 

 year. Indians comprised about 96 percent of the 

 total number. 



10. During 1930-1938, an average of 

 7,669 net lifts was made, 77 percent in the sum- 

 mer and 23 percent in the fall. Each fisherman 

 made 30 lifts in the summer and 10 in the fall. 

 The summer season covered an average of 57 

 days. 



11. Because of a maximum production 

 limit of 650,000 pounds of the principal species, 

 the number of individual lifts made by each fish- 

 erman and the length of the summer season 

 usually were inversely related to the abundance 

 of fish. When fish were numerous the summer 

 season tended to be shortened and consequently 

 the number of lifts reduced. 



12 . The catch per unit of effort (yield 

 per individual lift of small -mesh gill nets) during 

 the summer season was held to be the best index 

 of the abundance of fish of commercial size. 

 During 1930-1938, the walleyes were below aver- 

 age in abundance in 1930 and 1934-1936, and 

 above average in 1931-1933 and 1937-1938; the 

 yellow perch were below average in 1930-1931 

 and 1934-1936 and above average in 1932-1933 

 and 1937-1938. 1936 was a poor year but 1937 

 and 1938 were excellent for both species. These 

 rapid fluctuations in catch per unit of effort in 

 1936-1938 were thought to be due to changes in 

 water levels, in the condition of walleyes, in size 

 of mesh of gill nets, and in natural abundance . 

 The disturbing artificial factors made a convinc - 

 ing study of abundance impossible . A stabilized 

 fishery is a requisite for such a study. Whitefish 

 apparently have decreased in abundance from 1935 

 and northern pike from 1934 to 1938. 



13 . The age, growth, m aturity, and 

 condition of walleyes of Lower Red Lake were 

 studied. Length frequencies showed that 38 per- 

 cent of the walleyes in the commercial catch 

 were below the established minimum size limit 



of 14 inches, fork length (1938). The commercial 

 catches were dominated by individuals in the 

 fifth and sixth years of life. A length of 14 inches 

 to the fork of the tail was reached in about 5 years . 



14. Age, growth, maturity and condition 

 of the yellow perch of Lower Red Lake were 

 studied. Length frequencies showed that 90 

 percent ranged between 9 and 11 inches, fork 

 length . The collections were dominated by fish 

 in the seventh year of life. Females grew more 

 rapidly than males in each year of life. 



15. A historical account of the artiiicial 

 propagation of walleyes and whitefish on the 

 Red Lakes is presented. A continuous program 

 originated with the construction of a hatchery 



at Redby in 1924. 



16. The method of collecting and strip- 

 ping walleyes for spawn is described. Records 

 were obtained of the number of spawning males 

 and females taken and of the number of eggs 

 collected. The females produced an average of 

 23,153 eggs. The quantity of fry returned to 

 the Red Lakes varied from year to year in ac- 

 cordance with the number of eggs collected, the 

 number of eggs and fry supplied to other hatch- 

 eries or waters, and the variations in the per- 

 centage of hatch. In 1933-1938 about 35 percent 

 of the eggs collected were shipped to other 

 hatcheries. On the average, 92 percent of the 

 fry hatched at Redby were planted in the Red 

 Lakes, which represented only 33 percent of the 

 number of eggs collected. 



17. The method of collecting and stripping 

 whitefish for spawn is described. About 17 per- 

 cent of the whitefish eggs collected on the Red 

 Lakes were reported shipped to other hatcheries, 

 but on the basis of the total amount of fry pro- 

 duced, the data suggest that about 33 percent 



of the eggs were shipped. Rou^ly 43 percent 

 of the eggs collected were returned to the Red 

 Lakes as fry. On the average, 97 percent of the 

 fry hatched at Redby or 72 percent of the State's 

 output were returned to the Red Lakes . 



18. During 1927-1938, the Redby hatchery 

 produced an average annual yield of approximate- 

 ly 123,000 brown, brook, and rainbow trout fry. 



62 



