108 



THE RATE OF GROWTH OF FOOD-FISHES. 



other way. Dr Fulton insisted upon the same interpretation of 

 the terms 'immature' and 'mature,' in 1889^ and determined 

 the average size limit of immature individuals in the case of 

 several of the commoner species. 



His work led him to conclude that the following sizes repre- 

 sent the lowest length, without reference to sex, at which 

 maturity is nearly reached in the following species: 



Cat-fish 20 (?) inches. 



The practical application of our knowledge of growth-rates 

 depends largely upon the determination for each species of the 

 average size and age at which sexual maturity is reached. 



A large number of fishes may be caught and measured and 

 their sexual organs examined, and we may thus determine 

 roughly a mean minimum size for the attainment of maturity ; 

 and this has been done in a great number of cases. The results 

 of examination of a number of fishes caught by the ' Garland ' 

 show the following maximum and minimum sizes which were 

 sexually matured Whilst those below the minima were not 

 sexually mature, it does not follow that individuals above the 

 maxima no longer spawn, in fact, a cod of 46 inches is, on the 

 same Table, recorded as in the ' spent ' condition. 



1 T. W. Fultou, 1th Scot. FMi. Board Report, p. 161. 



2 T. W. Fulton, 10th Scot. Fish. Board Report, p. 239 a. 



