years, but other factors such as low water levels, 

 floods, sudden changes in temperature, and un- 

 favorable weather conditions reduced the numbers 

 collected in other years . For example, during 

 the spring reasons of 1934, 1935, and 1936, the 

 water level in Red Lakes v/as reported to be so 

 low that many walleyes, especially the larger 

 females, could not enter the streams to spawn. 

 At its lowest stage, in 1936, the water at the 

 mouth of Tamarack River was said to be only 

 about 4 inches deep. At the same time, the 

 depth at the mouth of Black Duck River was about 

 1 foot. By the spring of 1937, flood conditions in 

 Tamarack River prevented proper setting of the 

 pound net so the number of fish captured was 

 small and the number of eggs collected unusually 

 low. 



Publications of the State of Minnesota re- 

 port unfavorable weather conditions in the spring 

 of 1924, 1930, and 1931; in addition to low water 

 a sudden drop in temperature to almost winter 

 conditions continued for such a long period in 

 1934 that upon resumption of favorable weather 

 conditions the walleyes failed to return to spawn. 

 A W.P.A. project approved in 1935 and carried 

 throu^ 1936, which made extensive channel im- 

 provements in Tamarack River, should prevent 

 shallow -water conditions which impeded the 

 spawning migration . 



Again, the biennial reports of the Minne- 

 sota Department of Conservation state repeatedly 

 that the number of walleye eggs taken depends to 

 a large degree on reasonably uniform water tem- 

 peratures. An examination of the daily tempera- 

 ture and catch records indicates that if such a 

 correlation exists the relation is very general in 

 character. Sudden changes in the abundance of 

 fish occurred during the height of the season 

 without a change in temperature, and vice versa 

 - - sudden changes in temperatures occurred 

 without affecting the trend in numbers of fish as- 

 cending the stream . Apparently a considerable 

 latitude exists in temperatures that control move- 

 ments of spawning walleyes. For example, large 

 numbers ran in both Tamarack and Black Duck 

 Rivers during April 22-30, 1936, when tempera- 

 tures were low (mostly below 39° F., table 23). 

 In fact, the largest number of fish (17,096) taken 

 on Tamarack River in 1936 was caught on April 

 27, when the water temperature was 34° F. On 



the other hand, in 1937 large numbers were 

 caught during May 2-8, when water temperatures 

 were relatively high (mostly above 52 °F.). How- 

 ever, the normal range of the temperatures 

 during the main part of the spawning runs was 

 40°F.-48°F. and varied only from 5° F. to 8°F. 

 (7 of the 1 1 runs) . 



All available records of the number of 

 walleye females stripped, number of eggs ob- 

 tained, and average number of eggs per female 

 are contained in table 24. The calculation of the 

 number of eggs collected is based on an actual 

 count of 137,251 eggs per quart made in April 

 1938, by the superintendent of the Redby hatchery. 

 The computation of the average number of eggs 

 per female is low because the females were not 

 subjected to sufficient pressure and manipulation 

 to remove all the eggs and probably not more 

 than 70 percent were expressed from the average 

 female. The precaution against severe pressure 

 is necessary to ensure that females will survive 

 artificial spawning and will be in good physical 

 condition and free from internal haemorrhage 

 when returned to the water . 



The first artificially hatched walleyes 

 were deposited in the Red Lakes in 1919 when 

 560,000 fry were planted. (Table 25) . Not until 

 the Redby hatchery produced its first walleyes 

 in the spring of 1925 were regular plantings be- 

 gun. The tremendous variations in numbers of 

 fry planted in different years were related to Jie 

 differences in total number of eggs collected 

 each year , number of eggs shipped to other 

 state hatcheries, percentage of hatch, and num- 

 ber of fry produced at Redby used for stocking 

 other waters. 



Table 25 contains all available records 

 on total number of walleye eggs collected and 

 shipped from the Red Lakes, number of fry pro- 

 duced by the Redby hatchery, and number of fry 

 planted in the Red Lakes. During 1932-1938, an 

 average of 168,935,000 eggs was collected; the 

 smallest number was taken in 1937 and the larg- 

 est in 1938 . On the average, about 35 percent 

 of the eggs collected were shipped to other state 

 hatcheries . Of the remaining 65 percent, about 

 57 percent were reared to fry stage at Redby. 

 This percentage of survival does not substantiate 

 Mr. Thaddeus Surber's statement (Minnesota 



53 



