plus possibly a few individuals of the 19U7 year class made up 5l percent 

 of the total numbers of white crappies caught in trap nets. This sudden 

 recruitment resulted in the increase in catch observed during July. Addi- 

 tional recruitment from the I9U6 year class and the 19h7 year class kept 

 the white crappie catch from falling below the low catch level of June in 

 August and September. 



2, Losses from the White Crappie Population 



There is evidence of considerable mortality among older white crappies 

 during the summer (Figure 6). During Period I, 60 percent of the catch of 

 white crappies, that were three years old or older ("residual" population), 

 consisted of h and 5-year old fish. By Period IX these older fish made up 

 only seven percent of the catch. 



The trap net fished in previously unnetted Broken Arrow Slough during 

 Period IX caught too few white crappies to allow comparison of length- 

 frequency distribution here, with that of the catch from regular netting 

 stations during Period IX. However, it seems doubtful that enough white 

 crappies were removed from regular netting stations during the season to 

 effect noticeably the size structure of the white crappie population. 



No migration of older white crappies was noted during the season and 

 the loss of older fish was probably due mostly to natural mortality. 



3»_ Activity of the White Crappie and the Catch. 



Two fluctuations in the catch of the white crappie can be related to 

 changes in the activity rate. They are (l) the decreases in catch during 

 the first part of June, and (2) the increase in catch during the last part 

 of September. 



Changes in the rate of activity that apparently caused these catch 

 fluctuations are probably related to changes in water levels and trcn^jera- 

 ture. The decline in catch during the first part of June coincided with 

 the stabilization of the water levels after the spring high water period. 

 Dropping water levels may have caused the higher catch during Period I 

 and their stabilization may have resulted in the lower catch rate during 

 Period II o This drop in catch also coincided with the warming of the 

 water to above 70 degrees F. 



Examination of gonads of white crappies throughout the season showed 

 that spawning activities were probably at a peak when netting began (Table 

 6) „ Spawning activites declined steadily until raid-June when 96 percent 

 of the white crappies examined were found to have undeveloped gonads. 



There was no apparent change in catch rate from the "residual" popu- 

 lation as spawning activities declined and the increase in catch rate in 

 J"aly can be attributed to the entrance of 2-year-old white crappies into 



22 



