FISHERY BULLETIN: VOL. 75, NO. 1 



September 



GULF 



BAY 



REEF 



September 



TOTAL LENGTH (MM) 



FIGURE 2. — Gonad weight-length regressions for Atlantic 

 croaker by sex and month. The length of each line shows the 

 observed size range. 



(1930), Suttkus (1955), and Bearden (1964); and 

 size at maturity agrees with Pearson (1929), 

 Bearden (1964), Hansen (1969), and Hoese (1973). 

 The general similarity of croaker reproduction 

 suggests that 15 October, which approximates the 

 time of peak spawning, would be appropriate as a 

 defined hatching date in warm-temperate waters. 



100 



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O -> 

 z 



O 



a 



3 

 < 



n = 60 



Lj 



< 50 



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l 



-f=t- 



n = 120 



I 1 I I 



100 -r^ 



^ n = 448 



50 



100 1 

 50 



n = 378 



100 

 50 



O 50- 



z 



t^JS 



12 3 4 5 



50 



n=150 



L 



100 



n = 187 



iu 



100 



50 - 



-rf^l 3=^^, 



n = 137 



100 



^ n 

 50- | 





v^V ^|^ 



12 3 4 5 



GONAD CONDITION 



100-1 



50 



N n = 55 



100- 



50- 



100 



50- 



12 3 4 5 



FIGURE 3. — Gonad condition of Atlantic croaker by months and 

 areas. The ordinate represents percent of the sample. Gonad 

 conditions on the abscissa are: (1) immature or resting, (2) 

 maturation, (3) maturity, (4) reproduction, and (5) spent. 



SOMATIC WEIGHT VARIATION 



Somatic weight-length relationships varied 

 monthly, and these changes appeared to be as- 

 sociated with maturation and spawning. Peak 

 somatic weight occurred during June except in 

 fish smaller than about 140 mm. Somatic weights 

 predicted by the regression equations for other 

 months (Table 2) were compared with predicted 

 weights in June (Figure 4). The somatic weight of 

 individuals smaller than about 140 mm increased 

 from May to at least September. Fish about 140- 

 160 mm showed progressive somatic weight loss 

 from June to September-October. The smallest 

 fish greater than 160 mm, in general, showed the 

 greatest somatic weight loss (or smallest gain); 



TABLE 2. — Analyses for the regressions of somatic weight (7) in 

 grams on total length (X) in millimeters for each month. All 

 regressions were significant at a = 0.0001. 



Month 



Sample 

 size 



Equation 



Y = 39.5303 - 0.8538X + 0.0057X 2 



Y = 71.1692 - 1.3371X + 0.0076X 2 



Y = 120.4035 - 1.9159X + 0.0092X 2 



Y = 158.951 1 - 2.3706X + 0.01 03X 2 



Y = 148.7089 - 2.201 6X + 0.0097X 2 



Y = 73.4739 - 1 2980X + 0072X 2 

 y = 132.7087 -1.8537X + 0.0080X 2 



and somatic weight loss, in general, seemed to 

 progressively increase from June to September- 

 October. Somatic weight loss during the fall in fish 

 larger than 140 mm was greatest in September- 



112 



