2, Recruitment to the catch consisted of the sudden appearance of 

 the I9U6 year-class during July after the spawning season and the gradual 

 appearance of the 19Jj-7 year-class during and after the last part of July. 

 The recruitment affected catch fluctuations in two ways. First it caused 

 the increase in catch as the recruitment occurred, and secondj, it increased 

 the magnitude of subsequent catches and c atch fluctuations resulting from 

 changes in the rate of activity. 



3o The drop in catch during the first part of June is thought to have 

 been caused by a decrease in the rate of activity of the black crappie. 

 This may have been caused either by (1) stabilization of water level during 

 Period II; (2) water temperatures rising above 70 degrees F, during Period 

 II or (3) a combination of these two changes in the environment. 



U. The increases in catch during Augiist and September are attributed 

 to the combined effect of previous recruitment and increased rate of activity. 



WHITE CRAPPIE CATCH TRENDS 



During the nine periods of netting, 929 white crappies, weighing 

 U56 pounds were taken in the trap nets. Seasonal fluctuation of this 

 catch is shown in Table k which lists the mean catch per lift for each 

 netting period. Seasonal fluctuation in the catch of white crappies was 

 less than that already noted for black crappies. 



The white crappie catch dropped during the first part of June. After 

 this period no significant change occurred in the catch until the latter 

 part of July, when the catch almost doubled. By the last of August the 

 catch had declined to a level somewhat above the June catch rate. During 

 the last half of September, a small rise in catch was observed. 



1. Recruitment to the White Crappie Catch . 



Length-frequency of the white crappie catch during each netting period 

 is shown in Figure 6. All white crappies taken in trapnets during Period I 

 Here 7.0 inches long or longer. Age determinations from white crappie 

 scales collected during the netting indicate that mjst of these fish were 

 of the 19li5, I9I4.U and 19ii3 year classes - the "residual" population. 



Table 5 shows the relative numbers of "recruited" (I9I16 or younger 

 year classes) and "residual" (19U5 or older year classes) white crappies 

 taken during each netting period. These data have been used in Figure 7 

 to show the effect of recruitment upon catch. 



Recruitment to the white crappie catch did not begin until Period IV 

 (July 1-10) when the I9U6 year class made up 19 percent of the total catch 

 in numbers of fish. During Period V, (July 18-27) the I9U6 year class, 



17 



