LIFE HISTORY OF LAKE HERRING OF LAKE HURON 297 



Menzies (1912) found it impossible to estimate the age from the scales of an 

 Atlantic sahnon hatched in April, 1905, and regularly fed in a pond until its death in 

 August, 1911, when it weighed 4 pounds and 3 ounces. Although the fish had 

 spawned in January, 1910, and in March, 1911, no spawning marks were found on its 

 scales. 



Mohr (1916) examined the scales of 28 perch pike {Lucioperca sandra Cuv.), 

 which, reared in a pond from eggs laid in April, 1915, were killed November 13, 1915. 

 The fish averaged 9.3 centimeters in length and 4 grams in weight and their scales 

 showed no aim^uli. 



In August, 1914, Storrow (1916) placed a European wrasse {Labrus bergylta), 2 

 to 3 centimeters long, in an aquarium and found that by May 24, 1916, when 8 cen- 

 timeters long, this fish had formed two broad growth zones on its scales. The new 

 growth of 1916 had not yet started. 



Cutler's (1918) experuuents on 85 flounders and 52 plaice, though carried on 

 primarily to determine "the conditions necessary to the production of these annual 

 rings [p. 471]," give some direct evidence on the formation of annuli. The experi- 

 ments were continued from July, 1915, to October, 1916, and scales were taken in 

 July, 1915, and January, May, and October, 1916. The curves representuig the scale 

 growth of the fish (ages 2^ to 4}^ years, as determined by scales) in the control 

 tank during the experimental period show distinct minima (annuli) and maxima 

 (broad zones) growth rhigs and closely follow the temperature changes of the seasons. 

 Even the fish m two of the experimental tanks ("abundant" and "scanty") formed 

 distinct minima and maxima rings, which corresponded to winter and summer tem- 

 perature conditions, respectively. 



Eraser (1918), on examining scales taken January 29, 1917, from four artifi- 

 cially reared sockeye salmon hatched in the spring of 1913, reports that, "although 

 there is much sameness in the rate of growth mdicated throughout, it is possible in 

 almost every perfect scale to make out the winter check somewhat readily." 



To test Reibisch's otolith method, Williamson (1918) examined the otohths of 

 two plaice of known age, the one 4.5 centimeters long and 14 months old, the other 

 11.5 centimeters long and 2 years and 8 months old. The latter individual did not 

 show more rmgs than a specunen of the same size, which Reibisch believed was 11 

 months old. Williamson concludes, therefore, that Reibisch's claim that one ring 

 of an otolith stands for one year of life rests on no substantial basis. "His assump- 

 tions are unsupported by any satisfactory argument. His paper appears to be a 

 special pleadmg for the one-rmg, one-year hypothesis, not an attempt to discover if 

 age markings actually e.xist." Williamson considers the number of prominent rings 

 on the otoliths to be a measure of the size of the fish. 



Rich (1920) studied several series of scales from chinook-salmon fry and year- 

 lings of known ages and found that, "Compared with the scales of wild fish, those from 

 hatchery specuneus show an iiregular growth. There are frequent minor checks, 

 indicated by narrower rings; but, as a rule, the true winter check is less well marked 

 [p. 9]." 



Peart (1922) observed that annual growth is not nearly as well difl'erentiated on 

 the scales of artificially fed trout as on those of the wild fishes. The former scales 

 are read with some uncertainty, the doubtful area being confined to the first two or 



