LIFE HISTORY OF LAKE HERRING OF LAKE HURON 305 



until it becomes approximately 50 at a body length of about 22 centimeters, when 

 it increases slightly until death. Huntsman finds that in fish of different ages but 

 of the same length the older have the larger scales. The varying proportion of 

 small and large herring in an age group, therefore, would be partly responsible for 

 irregularities in the growth relations between bod}' and scales. 



Huntsman finds that the changes in computed values based on X dimensions of 

 herring scales are briefly these: "The length at the first winter period decreases 

 rapidly at first [with age], then remains stationary, and finally increases very slightly. 

 For the second winter period the length decreases at first, remains stationary, and 

 then slowly increases. For the third winter period the length is at first stationary and 

 then slowly increases. For the remaining periods the length increases from the first, 

 but more at the beginning than later [p. 76]." 



In Pomolobus pseudoharengus (alewife) the body scale ratios show that the 

 posterior field grows at the same rate, relatively, as the whole body after a body 

 length of 3 centimeters is reached, and that at least in the beginning the anterior field 

 and the transverse diameter grow proportionately faster than the whole body. The 

 later increase in the latter shows diflferences, which apparently are characteristic of 

 the several regions of the body. 



In Tautogolabrus a^spersus (cimner) -y at first decreases with age and subse- 

 quently increases, while similarly in Pseudopleuronectes americanus (flounder) ^ 



decreases at first and finally increases with age. 



The lack of correspondence between fish and scale growth will account for a 

 considerable portion of the differences between observed and computed values. There 

 is a "lack of correspondence in growth between the two principal layers of the scale, 

 and even between the parts of one layer. * * * The best diameter for use in 

 length calculations, if no correction is to be made, is the transverse in the Clupeidse. 

 The posterior field would be preferable, but the indistinctness of the annual rings in 

 that region renders it useless [p. 89]." 



In another paper Huntsman (1918) points out that by the use of a "movable 

 curve" cut out of cardboard or wood one can compensate for the differential growth 

 of the scale compared with that of the body and for the dift'erence in the time of 

 origin of the various scales according to size. 



vSavage (1919) states that three factors may cause the low computed values for 

 the first year of life in the marine herring: (1) Earlier outward migration from the 

 inshore waters of the larger yearlings, which would make the actual length values 

 for 1-year-old fish too high, (2) the variability in the length of the head and tail with 

 age, and (3) the possible variation in the position of the basal line of the scales with 

 growth. 



Jarvi (1920) compared the calculated with the actual length values for fish 

 {Coregonus albula) of the same year class. He found that, in genei'al, each year that 

 intervened between the year of capture and the year for which calculations are made 

 introduced an error of 0.5 centimeter in length calculations. That is, the calculated 

 values will be 0.5, 1, 1.5, 2, 2.5, 3, or 3.5 centimeters too low, depending on whether 

 1, 2, 3, 4, 5, 6, or 7 years, respectively, intervened. He found the error to vary from 



