170 



BULLETIN OF THE BUEEAU OF FISHERIES 



SIZE AND AGE AT MATURITY 



Sexually matured black drum with a total length range from 27 to 105 centi- 

 meters (10.5 to 41.6 inches) were taken. Only fish that possessed developing sexual 

 products (granular roe in the females) were sexed, thus obviating personal errors in 

 judging the state of development. 



It ^vill be observed, by inspection of Table 16, that the drum found in a ripening 

 or spawning condition during July to October, 1926, were of smaller minimum and 



LENGTH 



OF FISH 



MM 10 20 30 

 SCALE LEhiGTh 



10 20 

 JCALE WIDTH 



40 



Fio. 22.— Correlation between scale length and width and total body length in the black drum. 

 The average values of the scale lengths and widths corresponding to a succession of body 

 lengths lie nearly upon a straight line, indicating that on the average the growth increment 

 of the scales is a constant proportion of the giowth increment of the fish 



maximum length than those taken during the main spawning period in the winter 

 and spring of 1927. This difference extends particularly to the older and larger 

 fish, only one drum above 58 centimeters (22.8 inches) being taken during 1926, 

 compared with many secured in 1927 by the writer and by commercial fishermen. 

 This condition is unaccounted for at present. One possibihty, however, is that many 

 of the youngest maturing fish (I class) reach sexual maturity either several months 

 prior to or after the older classes spawn. 



