230 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the fourth year further growth compensation 

 reduced the maximum difference below the first- 

 year value. 



It appears to be characteristic of the growth of 



the Lake Erie yellow perch that a first-year 

 advantage in size is increased in the second year. 

 Growth compensation occurs in the third and 

 fom-th years of life. 



PROPORTION OF SEASON'S GROWTH COMPLETED AT TIME OF CAPTURE 



Table 11. — Increment of growth completed by Lake Erie 

 yellow .perch at certain dates in 1927 



' Includes fish whose sex was not determined. 



Although the dates of collection of the Lake 

 Erie yellow perch were not distributed in such a 

 manner as to permit a thoroughgoing study of the 

 progress of growth during the season, scattered 

 data based on samples taken after June 30 do 

 provide a certain amount of information. The 

 calculated increments of growth added in the year 

 of capture and the percentages of these increments 

 of the year's total growth are shown in tables 11, 

 12, and 13 for three age groups collected in 1927, 

 1928, and 1929. The growth increments of perch 

 from late-season collections have been considered 

 to represent the total season's growth and hence 

 have been assigned the percentage of 100. The 

 selection of these late-season samples was not 



Tablk 12. — Increment of growth completed by Lake Erie 

 yellow perch at certain dates in 1928 



1 Includes fish whose sex was not determined. 



arbitrary, but was based on a careful study of 

 the growth increments of fish in the collections of 

 single days. For example, detailed data for 1928 

 (not given here) demonstrated that the growth 

 increments of perch captured on October 16 were 

 as large as those of fish taken on November 20. 

 It was assumed, therefore, that no growth occurred 

 after October 16 in that year, and consequently 

 the sample of that date was included as part of 

 the "late-season" collection. In 1927, on the 

 other hand, the growth increments of perch cap- 

 tured on October 24 were noticeably smaller than 

 those of fish taken on October 31 and on various 

 dates in November. Accordingly, the October 

 24 sample was excluded in the computation of the 



