NATURAL HISTORY OF REDFISH, ETC., OF TEXAS 



169 



scales (annuli) have the nature of bilateral breaks or interruptions in the circuli 

 pattern of the scale, most evident at the lateral terminals of the circuli. Many of 

 the younger fish, however, in addition to the lateral terminal checks, show closer 

 approximations of circuli formed during the retarded winter growth. In most 

 respects the scales of the black drum closely resemble those of the redfish, both in 

 size and structure, as well as in the nature of the winter-growth check. 



Figure 21 illustrates the relation between age and length, secured by a study 

 of the scales of several hundred drum. No fish over 60 centimeters (23.3 inches) in 

 length has been included in this figure because of the present unreliability of age 



CMS. 10 20 50 40 50 



10 



20 30 



30 SO 



AGE 

 IN YflS. 

 4 



3 



2 



INS. 3.9 76 (I.S ,'5.7 l^.7 3.9 7.8 II.& 15.7 /9.7 23.6 



Fig. 21.— Age of black drum according to length, as indicated by winter growth checta on scjiles 



determination as applied to the larger fish. The first four years of age are represented 

 fairly well in the length distribution ranging from 1 to 60 centimeters, although 

 insufficient numbers of fish prevent the discernment of any definite modal lengths 

 at any particular age. The scale collections were small, unfortunately, but the 

 results obtained seem to justify more intensive work in the future on the analysis 

 of age of the drum by means of the scale method. 



An incomplete examination of many scales from fish measuring more than 

 60 centimeters (23.3 inches) indicated that 5 years of age may be attained when the 

 fish reach a length of about 60 centimeters, and that they are 7 to 9 years of age by 

 the time they reach a length of 75 to 85 centimeters (30 to 34 inches). 



