3. Activity of the Bluegill and the Catch . 



Apparently all the significant fluctuations in the catch of blue- 

 gills, except the rise during July due to recruitment, were influenced 

 by changes in the rate of activity of the fish. The drop in catch rate 

 during June can, like similar drops in the white and black crappie 

 catches, best be attributed to a decreased activity rate alone. Also 

 the increase in bluegill catch during August and September can largely 

 be attributed to an increase in the activity rate of bluee;ills. It 

 should be noted however that most of the fish affected by this increase 

 in activity rate were "recruited" bluegills that had not been available 

 during the early netting periods. 



Changes in activity rate were probably related to environmental 

 changes. The drop in catch during the first part of June coincided 

 with the stabilization of water levels after the spring high-water 

 period. The drop in catch also was coincidental with water tempera- 

 tures rising above 70 degrees F. 



It» The Effects of Spawning Activities . 



A summary of data gathered from examination of the gonads of blue- 

 gills caught in trap nets during the season is presented in Table 9. 

 Gonads from the bluegills indicated that many were spawning when the 

 netting began in May. Spawning activities apparently declined during 

 July and by the first of August no fish with ripe gonads were taken. 



There was no change in the catch of the "residual" bluegills which 

 coincided with change in the spawning activities as measured by gonad 

 analysis. However the 2-year-old bluegills, (like the 2-year-old black 

 crappie and white crappie) entered the catch with the older fish as 

 spawning activities declined. 



Most of the 2-year-old bluegills examined had either ripe or spent 

 gonads. They were sexually mature and apparently spawned apart from the 

 older fish during the first part of the 19i|8 season. 



SUMMARY OF BLUEGILL CATCH TRENDS 



1. The means of bluegill trap net catches for the nine netting 

 periods fluctuated between 1.3 and 5l.l fish and 0.5 and 13.5 pounds 

 of fish per net lift. There was (1) a sharp drop during the first 



part of June and (2) a continual rise during July, Auj^.ust and September. 



2. The sharp drop in catch during the first of June is thought to 

 have been caused by a decrease in the activity of the bluegills. This 

 decrease may have been caused by (1) stabilization of water levels after 



30 



