It will also be noted from Figure 3 that smaller black crappies were 

 caught in increasing numbers during later periods. Age determinations 

 from scales of these fish demonstrated that they were of the 19i|6 and 

 19it7 year classes. These 1- and 2-year old black crappies may be termed 

 "recruitment" for they were (l) the younger fish not large enough to be 

 held in the nets during Period I, and/or (2) not present in the area 

 being netted during Period I. 



Table 2 lists the mean catches of "residual" and "recruited" black 

 crappies for each netting period. The first recruitment to the catch 

 began in Period II (May 31-«June 9) when a few individuals of the 19ii6 

 year class were taken. A month later (Period IV) these 2-year old fish 

 made up 33 percent of the catch in numbers of fish, A few of the 19U7 

 year class entered the catch during the following netting period (V) 

 when "recruited" fish made up $9 percent of the total black crappie catch. 

 During August and September, the 19U7 year classes entered the catch in 

 increasing numbers. The total "recruited" fish made up from 39 to 65 

 percent of the mean black crappie catch of the last four netting periods. 



The appearance of the 19U6 year class during June and July did not 

 coincide with the growth of these fish to catchable size. The nets 

 readily retained black crappies as small as S inches and growth analysis 

 of the I9U6 year class demonstrated that most of these fish were larger 

 than that when the netting began in May, Their absence at that time and 

 their sudden appearance in quantity during July suggests that they were 

 not associated with older fish during the early part of the season but 

 joined them during July. 



Figure k shows graphically the effects of recruitment ipon the catch. 

 The rise in catch during July probably reflects the effects of recruitment 

 alone; that is more fish large enough to be held by the nets were available 

 to be caught. The still greater catch rate in August and September is 

 probably the result of (1) augumentation of the population by previous re- 

 cruitment and (2) an increase in the rate of activity of all crappies in 

 the population during late summer. Catch of the nets can be regarded as 

 an arithmetical product of abundance times activity and large catch 

 fluctuations may be expected when there is a change in the activity rate 

 of large populations, 



2^ Losses from the Black Crappie Population . 



It is likely that some of the increase in size of the catchable 

 black crappie population during the fowr and a half months was offset by 

 various types of losses such as natural mortality, fishing mortality and 

 perhaps migration from the area. Such losses would influence the catch 

 at the end of the season. From the present data there is no means of 

 estimating the total loss to the population. However there is some 

 evidence of a greater loss among older age classes than among 3-year-old 

 fish. During Period I, h and 5-year old black crappies made up about 35 

 percent of the catch in numbers of fish; the remaining 65 percent con- 



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