YELLOW PERCH OF LAKE ERIE 



257 



The range of fluctuation of K for the age groups 

 of Lake Erie yellow perch extended from 1.72 to 

 2.61. The individual yellow perch were found to 

 have values of K ranging from 1.13 to 3.23, with 

 the average 1.91. Comparisons of these values of 

 K with those found in other waters of the Great 

 Lakes reveal that the yellow perch of Lake Erie 

 were a little heavier than the ones in Saginaw Bay 

 (Hile and Jobes 1941), about equal to those in 

 Green Bay, and somewhat more slender than the 

 yellow perch in northwestern Lake Michigan (Hile 

 and Jobes 1942). 



Influence of rate of growth on value of K 



The possibihty that the values of K of the age 

 groups were influenced by varying proportions of 

 faster or slower growing individuals has been in- 

 vestigated. Table 34 permits comparisons of K 

 for yellow perch of the same length but of different 

 ages and for fish of different lengths but of the 

 same age. All comparisons have been limited to 

 fish collected in the same year and month. The 

 data have been limited further to the 1927 and 

 1929 collections from trap nets since those collec- 

 tions had the most suitable distribution of the age 

 groups, that is, contained adequate samples from 

 more than one age group. It may be seen that 

 there were no consistent differences between the 

 values of K for fish of the same length but different 

 age. In other words, neither the older (slow 

 growing) nor the younger (rapid growing) yellow 

 perch maintained a consistent advantage. This 

 indication that individual growth rate did not 

 influence individual condition is supported by the 

 fact that the longer (more rapid growing) indi- 



Table 34. — Comparison of condiiioti (K) in Lake Erie yellow perch at different ages and lengths taken by trap nets 



[Number of specimens in parentheses] 



had the same values in November 1927. Only 

 three comparisons were available between age 

 groups IV and V, and in each the older age group 

 had the lower K. In general, fluctuations of K 

 with age may be considered random among all 

 age groups in which gear selectivity is absent or 

 unimportant, although there was a tendency for 

 a progressive decrease ^vith age during the period 

 April to September. It may be justified to con- 

 clude, however, that generally condition is inde- 

 pendent of age in the Lake Erie yellow perch. 

 No computation was made of average values of K 

 for all data combined since the combined effects 

 of monthly variations and of variations in the 

 numbers of specimens would cause these averages 

 to be of little significance. 



Table 33. — Coefficient of condition (K) of Lake Erie yellow 

 perch according to age, month, and year of capture 



[Number of specimens in parentheses] 



