YELLOW PERCH OF LAKE ERIE 



239 



1929. The reduction in the annual fluctuation of 

 the position of the modal length intervals of the 

 gilled fish in the gill-net collections as compared 

 with the impounding-net samples can be ascribed 

 to the greater selectivity of gill nets. 



The lengths of the modal frequencies of fish 

 gilled in both shoal and buU nets were without 

 exception greater than those of fish caught in 

 impounding nets in the same year. The general 

 differences between the length distribution of the 



3 5 



fish from impounding, shoal, and bull nets (all 

 collections combined) are shown graphically in 

 figure 9. The curves are based on the totals of 

 table 17, expressed as percentage frequencies. 

 The graph includes only the length range over 

 which representation was continuous. As men- 

 tioned in the preceding paragraph, the much more 

 compact distributions and the greater average size 

 of perch in the gill-net collections may be attrib- 

 uted to net selectivity. The occurrence of small 



3 



2 5 



U 



z 



3 



o 



< 



z 



UJ 



o 



2 



I 5 



I 



TOTAL LENGTH 



9 

 I N 



I 



1 2 



N C H E S 



Figure 9. — Percentage frequency distribution of total lengths of Lake Erie yellow perch in collections from each kind of 

 gear. Curves extend only over length range where representation was continuous. 



