36 



THE ROYAL SOCIETY OF CANADA 



summer and ninth year there was a decided diminution of the growth 

 of the fish. This may be interpreted as due merely to poor feeding 

 conditions, but from comparison with the 122 cm. fish it seems more 

 prol)able that it represents a spawning period, which however was of 

 much shorter duration than in the younger fish, ceasing with the tenth 

 winter band instead of being continued to the twelfth. In the tenth 

 summer the numl)er and wide spacing of the lines indicate a rapid growth, 

 which was continued during the succeeding year, and then there follows a 

 broad zone in which the lines are all greatly concentrated, but in which 

 seven winter bands (13-19) are quite distinct in some scales. It cannot 

 be said that this entire zone represents a continuous period of repro- 

 ductive activity, for the intervals between successive winter bands 

 vary in width and the lines in some of the intervals are much 

 less distinct than in others. More probably periods of reproduc- 

 tive activity alternated with periods of normal, though diminished, 

 growth throughout the seven years represented by the zone; indeed 

 it would seem that the first three years were essentially reproductive 

 periods, and possibly the fifth year also, but this cannot be stated with 

 certainty. 



A band of summer lines succeeds the last winter band of the zone 

 just described, and if no error has been made in the count of the bands 

 the fish was in its nineteenth year when captured. 



Two facts of special importance are revealed by these observations : 



1. The growth of the fish is relatively slow. A length of 66.5 

 cm. represents a growth of seven years, that of 122 cm. twelve years, 

 and that of 152 cm. about nineteen years. 



2. The fish does not become sexually mature until about its eighth 

 year. 



In this connection mention may be made of some observations by 

 Holt* on Halibut from Iceland and the Faroe Islands, in which from 

 an examination of the reproductive organs he comes to the conclusion 

 that male fish reach maturity when about 30 in. in length (72.5 cm.), and 

 females when they are at least 36 in. (90 cm.). Owing to the conditions 

 under which my observations were made, I was not able to determine 

 the sex of the fish examined, but leaving this point aside, Holt's obser- 

 vations correspond fairly well with those obtained from the examination 

 of the scales, my results indicating that maturity occurs in fish some- 

 where between 66.5 cm. (26.6 in.) and 122 cm. (48.8 in.) ; but the scale 

 examination adds the important information that such fish are in their 

 eighth year. 



*HoLT, E. W. L. — North Sea Investigations. Journal Marine Biol. Assoc. 

 N.S. II, 1892. 



