298 BULLETIN OF THE BUREAU OF FISHERIES 



three years of life, the years of sexual immaturity. Peart ascribes this "vagueness 

 of artificial scales" to the attempts of the breeders to make their fish grow continu- 

 ously. 



In a previous paper (Van Oosten, 1923) I have shown that scale age and fish age 

 agreed in whitefish 8 and 9 years of age — ^.the oldest fish yet recorded in whicli the 

 nimiber of annuli was demonstrated to agree with the years of life of the fish. 



My conclusions were based on a study of the scales of 27 whitefish {Coregonus 

 clupeaformis) hatched and reared in the New York Aquarium. The fish were hatched 

 in January, 1913, and died (or were killed) at intervals between August 13, 1920, 

 and January 3, 1922 — a period of 16 months. The fish received had died (been 

 killed) during every month of the year except November. It was shown that the 

 first eight specimens received, which ranged from 7 years and 7 months to 8 years 

 and 2 months in age possessed scales with seven completed annuli and various 

 amounts of marginal growth. The eighth annulus was first completely formed in the 

 specimen killed April 28, 1921, at the age of 8 years and 3 months. The fish received 

 after April, 1921, whose ages varied from 8 years and 4 months to 9 years, showed 

 eight completed annuli and various amounts of marginal growth on their scales. 

 Five photomicrographs of scales taken from fish killed in different months were pub- 

 lished. I concluded that the annuli m whitefish scales are "of the same number as 

 that of the winters of the fish's life, if we exclude the first one in which the fish was 

 hatched." 



In October, 1919, Dannevig (1925) placed 150 codlings, 8 to 12 centimeters 

 long and presmnably about 63^ months old, in a hatchery pond and studied the scales 

 of 61 of these caught at irregular intervals until May 23, 1922. The fisli were fed only 

 from May to the middle of December in each year. In October, 1919, small sclerites 

 were situated at the edge of the scales of all fish. In the following March, May, and 

 June the smaller fish still showed small sclerites at the margin of the scales, but the 

 larger specimens showed large sclerites. The fish taken in December, 1920, March 

 and April, 1921, had large sclerites at the edge of their scales and two minimum-growth 

 zones situated at a considerable distance from the margin, although the December 

 specimen was only about 203^ months of age. The specimens taken October, 1921, 

 showed small sclerites at the edge of their scales, while those taken May, 1922, 

 showed three minimum-growth zones and a large marginal growth of wide sclerites. 

 It is unfortunate that the more critical data of winter specimens were not obtained. 



The experunent, as far as it goes, probably confirms the age hypothesis. Dan- 

 nevig concludes that in the majority of individuals the zones with minimum sclerites 

 are autumn zones and tell how many autumns the fish lived. "The greatest diffi- 

 culties appear when deahng with the slow-growing individuals, the lack of large scle- 

 rites makes the resting zones to intermerge, being often only separated by a few medi- 

 um-sized sclerites. On the other hand, such medium sclerites might appear in the 

 middle of a resting zone; in such cases we may erroneously be inclined to count two 

 zones. This is the case especially when dealing with the mediinn-sized material 

 from May and June, 1920. " 



H. Thompson (1926) attempted to show experimentally the effect of regulated 

 and plentiful food supply on the general metabolism of haddock, codling, whiting, 

 and saithe introduced into tanks at various times during the period 1922-1925. The 



