HALES: ROUND SCAD IN THE SOUTH ATLANTIC BIGHT 



Table 7.— Frequency of occurrence, volumetric displacement, and relative abun- 

 dance of prey of Decapterus punctatus by season. Abbreviations as in Table 6; 

 r = range of fork lengths. 



CO 



X 



o 



< 



CO 



I- 



Q- 



:e 



LlI 



30- 



2 5- 



20- 



0- 



5- 



(40) 



(52) 



0300 0700 1100 1500 1900 2300 

 TIME OF COLLECTION(E.S.T) 



Figure 6.— Percent of empty stomachs of Decapterus jmnctatiis 

 collected at different times of day. Samples were pooled over 4-h 

 intervals, of which midpoints are given, (n) is sample size. 



Table 8.— Appearance of marginal increments of otoliths of 

 Decapterus punctatus collected at different times of day. Data in- 

 dicate increments are formed daily. N = number of specimens, 

 times are Eastern Standard Time. 



FLof 

 specimens (A/) 



Time of 

 capture 



Marginal increment 



42-55 mm (4) 

 17-22 mm (11) 

 13-24 mm (4) 

 35-53 mm (8) 



0239-0257 

 0812-0817 

 1506-1516 

 2045-2053 



wide, transparent 

 thin, dark 

 wide, transparent 

 wide, transparent 



was proportional to fork length throughout the size 

 range (14-143 mm FL) for which age determination 

 was possible (logio OL (in mm) = 0.82 logjo FL (in 

 mm) - 1.61; r^ = 0.99, n = 71). 



The thickness and structure of growth increments 

 changed in consistent ways in lapilli (Fig. 7). Ten 

 to twelve faint daily increments surrounded a cen- 

 tral core, which contained the primordium (Fig. 8). 

 The next 10-15 increments increased in thickness, 

 and the following 20-25 increments gradually de- 

 creased in thickness. A distinct change occurred at 

 this point, and increments became thinner and more 

 regular. Increments appeared uniform in thickness 



259 



