LAKE HERRING OF GREEN BAY. LAKE MICHIGAN 



111 



Table 25. — Subsequent and/or previous frequency distribution of the calculated length of lake herring that had the same cal- 

 culated length at the end of a particular year of life 



(Based on all age group III Ash of tbe 1950 pound-net collections] 



fish and also for other animals as well. Hile 

 (1941, p. 305) stated that— 



A wealth of experimental evidence supports the view 

 that among animals in general the inherent capacity for 

 growth is lost chiefly through its exercise, and, conversely, 

 the failure to grow does not entail necessarily the loss of the 

 natural ability to grow. 



In support of this statement he cited the work of 

 several authors on such widely separated groups 

 as mammals, fish, salamanders, and insects. 

 Hodgson (1929), on the other hand, demonstrated 

 that compensatory growth could be a perfectly 

 natural result of comparisons of fish of different 

 age (fish that have the same number of anniili 

 that were of different ages because they hatclied at 

 different times during the season). Hodgson 

 explained his view that growth compensation is 

 "apparent" by comparing identical hypothetical 



growth curves that started at different points along 

 the time axis.* 



Later Hile (1941) applied Hodgson's principle to 

 the sigmoid growth curve of the rock bass to 

 explain the variety of relations!iips among the 

 annual increments of different yearling size groups. 

 A similar use of the growth curve of the Green Bay 

 lake herring is presented in figure 6. Here the 

 two growth curves are identical but fish .1 hatched 

 and started to grow at time 0^, whereas fish B 

 hatched and started to grow at time Oa. At time 



' Hodgson (1929) felt that a bimodal length-frequency distribution of first- 

 year sea herring resulted from a long irregular hatching period and estimated 

 that hatching extended over about 3 months. Hile (19.36) also attributed a 

 bimodal first-year lenpth-frcquoncy distribution of cl.scoes In certain year 

 classes in two Wisconsin laltes to irregular weather conditions during the 

 hatching period that resulted in irregular and prolonged batching. It has 

 been impo.ssible to learn anything about the hatching of lake herring in Green 

 Bay. but it is believed that hatching may extend over a period of several 

 weeks since spawning occurs over a period of 4 to 6 weeks. 



