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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 24. — Calculated growth of lake herring grouped by size in different years of life 



[Based on IV-group fish of Feb. 16, 1949, sample collected at Schumachers Point. Terminal groups contain 15 percent and middle groups 35 percent of total 

 number of fish. Mean lengths for the year of life of grouping and corresponding growth increments are italicized. Maximum difference between lengths in 

 parentheses] 



The characteristics of growth compensation 

 brought out by these authors for this species were 

 similar, in that the shorter fish at the end of the 

 first year of life tended to grow more in the 

 following year than did the longer first-year fish. 

 The studies demonstrated further that the initial 

 advantage of the longer first-year fish was not 

 completely overcome. This type of compensatory 

 growth was also found in the Green Bay herring 

 (table 24), 



Previous investigators have examined the phe- 

 nomenon of growth compensation by dividing fish 

 into different length groups according to the first 

 year's growth and comparing subsequent growth 

 of these groups. It is not to be anticipated, how- 

 ever, that these first-j^car groupings will retain 

 their identities in subsequent years; that is, indi- 

 vidual growth will vary sufficiently so that a new 

 grouping on a similar basis in later years will show 

 some exchange of fish between the original groups. 

 In lake herring both previous and subsequent 

 growth of fish of the same length in a particular 

 year of life varied widely (table 25). For example, 

 the 47 lake herring that were 7.0 to 7.4 inches long 

 in the second year of life had ranged from 3.5 to 

 5.9 inches in their first year and from 8,5 to 10.9 

 inches in their third year. 



Because of the tendency for fish of a given length 

 in a particular year of life to derive from fish of a 



considerable length range in earlier years and, in 

 turn, to contribute to a wide range of length in 

 subsequent years, it is to be anticipated that the 

 growth of fish of different length groups will vary 

 according to the 3'ear of life in which the grouping 

 is made. This expectation is met by the data of 

 table 24 in which length groupings of fish of a 

 single age group are made on a similar basis (see 

 caption of table) for each year of life. The 

 maximum difference (difference between mean 

 lengths of the terminal group) without exception 

 was greatest for the year of grouping, and de- 

 creased consistently in previous and subsequent 

 years of life. The decrease from the year of 

 grouping toward earlier years reflects the diverse 

 origin of the fish with respect to their positions 

 in the length distributions in those earlier years. 

 Tlie decrease in the maximum difference in years 

 of life following the year of grouping represents a 

 tendency toward convergence of size. 



Further information on these growth relation- 

 ships is to be had from the annual growth incre- 

 ments of length shown at the right of table 24. 

 Here it is seen that the increments in each year of 

 life preceding the year of grouping tended to fall 

 in the same order as in the grouping year itself, 

 l)ut that in subsequent years the increments tended 

 to fall in the reverse order. 



As a general biological phenomenon, growth 

 compensation may reflect principles holding for 



