for judging the validity of such means must be used if the mean catches 

 from the 10-day netting periods are to be compared. An atten^jt was made 

 to judge sampling errors by standard statistical procedures, but the data 

 appeared not amenable to this type of treatment. The distribution of the 

 catches is skewed and random sanpling of the individual fish in the popu- 

 lation cannot be assumed. As pointed out by Moyle (1950) for the catch 

 of gill nets, the skewness of the catch pattern and the apparent non- 

 random nature of the sampling probably reflects the associative patterns 

 of the fishes themselves. 



Instead of standard error a more general and empirical method has 

 been used for judging the validity of catch means. Mean catch for each 

 species, in terms of weight and numbers of fish per lift, was calculated 

 for each of the It or 5 nets used during each netting period. If the mean 

 catch in at least 7$ percent of the nets - that is, 3 out of U or ii out 

 of 5 - was higher or lower than in the preceding period, the trend was re- 

 garded as real and probably not due to sampling errors. Changes of a 

 lesser degree are considered to be uncertain. All fluctuations discussed 

 in this paper meet this requirement, unless otherwise specified. 



This method of judging reliability of means is similar to that of 

 Hubbs and Perlrautter (19U2) who in attempting to apply statistical pro- 

 cedures to fish systematics concluded that "Even when no single sample 

 of one group can be demonstrated as significantly different from that of 

 another group, a true distinction between the two categories must never- 

 theless be accepted, if the difference is shown consistently by enough 

 small samples of each group." 



SEASON TREiraS IN CATCH OF TRAP NETS 



During this study 12,810 fish weighing 11,25U pounds were taken in 

 trap nets. Thirty-five species of fish were caught but only 11 species 

 were taken in quantities adequate to demonstrate catch trends. Arranged 

 in the order in ^*iich they -^jill be discussed they are: 



Black crappie - Pomoxis nj-gro-maculatus 



White crappie - Pomoxis annularis 



Bluegill - Lepomis macrochirus 



Northern pike - Esox lucius 



White bass - Lepibema chrysops 



Channel catfish - Ictalurus lacustris punctatus 



Flathead catfish - Pilodictus olivaris 



Northern redhorse - Moxostoma aureolum 



Carp - Cyprinus carpi o 

 Carpsucker - Carpiodes spp. 

 Sheepshead = Aplodinotus grunniens 



