150 



BULLETIN OF THE BUREAU OF FISHERIES 



in the IV-year class. The youngest or 0-year class (a few weeks old) is not repre- 

 sented, of course, in the commercial catch. The abrupt curve at about 32 to 33 

 centimeters (12.6 to 12.9 inches) results from the selection of the gear as well as a 

 legal minimum-size market limit at 36 centimeters (14 inches). 



Table 10. — Length-frequency distribution of 357 market redfish taken in Laguna Madre, Tex., Novem- 

 ber to December, 1925, by commercial seines 



A study of the annual winter growth check, as indicated on the scales of the red- 

 fish, afforded verification of the age estimates made from the length frequency. The 

 redfish spawned in the late fall rarely show, on the scale structure, any evidence of a 

 reduced growth rate during the first winter, but after the first winter definite changes 

 occur in the scale pattern during the cold months of the year, which enable the age 

 of the fish to be determined with some degree of accuracy. The scales of the species 

 become heavily calcified and opaque after the second or third year, and it is necessary 

 to treat them with a weak solution of hydrochloric acid in order to make them trans- 

 parent. 



The nature of the redfish scale is similar to that of the black drum, and the winter 

 growth check in both species essentially consists of a break or interruption in the 

 pattern of the circuli on the scale, particularly along the lateral terminals of the circuli. 

 These breaks or irregularities probably are produced by the greatly accelerated growth 

 of the fish and its scale in the early spring after a winter period of retarded growth. 

 Closer approximations of the circuli along the radii during the winter season are 

 evident on the scales from the younger fish, with these appro.ximations forming so- 

 called "bands," ending along the lateral terminals in pronounced breaks in the circuli 

 arrangement. 



The abundance of scale material allowed the fact to be proved that these scale 

 checks were formed annually during the winter season, with, however, the first winter's 

 check usually absent or faint, owing probably to the small size of the fish during the 

 first winter. Measurements of these annual checks for the purpose of calculating 

 the average growth were not deemed practical, since the decalcification of the scales 

 caused the latter to change their size. 



The ages of 300 unselected redfish were obtained by counting the number of 

 winter scale checks, including any check that may or may not have formed during the 

 first winter, when the fish were but a few months old. Thus, in the case of a collec- 

 tion of fish taken during April and May, 1926 (fig. 11), 35 redfish, ranging from 

 8 to 21 centimeters in length (3.1 to 8.2 inches), were found to be in their first year 

 (having been spawned the October or November previous and in most cases not 

 showang a winter check on the scales); 22 redfish, ranging from 40 to 51 centimeters 

 (15.7 to 20 inches), were found to be in their second year (possessing, in &\\ cases, one 



