MANOOCH: REPRODUCTIVE CYCLE OF RED PORGY 



central canal of testes from January through 

 April. 



Female red porgy were separated into two 

 maturity classes: Immature fish, and mature 

 (maturing, ripe, and spawned). No individuals less 

 than 260 mm and all fish greater than 360 mm were 

 sexually mature (Table 1). The linear regression of 

 percent maturity (iO on total length (X): 



Y = -211.2946 + 0.8576X, r = 0.94, 



was significant at cc = 0.01. Half the females 

 were mature at 304 mm. By inserting age data 

 (Manooch 1975) to the graph, age at sexual matu- 

 rity was determined. Regression of age with 

 length suggests that none of the age I fish, 37% of 

 the age II, 81% of the age III, and 100% of the age 

 IV fish were mature. Some age II and III females 

 apparently showed the characteristic, seasonal 

 maturation of ovaries but did not spawn the first 

 year, because several specimens had ovaries con- 

 taining absorbed ova during the peak spawning 

 period. 



Table L-Number and percentage of female red porgy, grouped 

 into 20-mm size categories, staged as immature and mature 

 (maturing, ripe, and spawned) off North Carolina 1972-74. 



Mature 

 (no.) 



Mature 

 (%) 



Total 



60 















4 



2 



7 



29 



34 



57 



80 



75 



214 



502 



0.0 

 0.0 



0.0 



33.3 



15.4 



58.3 



87.9 



87.2 



100.0 



100.0 



100.0 



100.0 



soo- 



o 



z 

 < 



a 

 z 



300- 



200- 



100- 



300 



450 500 550 



TOTAL LENGTH IN MILLIMETERS 



500- 



a 



z 



< 400- 



2 300- 



a 



Z 200- 



3 



In F*cundity = l 7369 + t 5178 (Ln Wl) 

 ,' = 70 



I I 



I I ' — I— ' — r 



90C 

 WEIGHT IN GRAMS 



- 1 . I I I 



300 500 700 900 IIOO 1300 1500 1700 1900 



Figure 3.-Relationship between fecundity and two predictors: 

 (top) length and (bottom) weight of 50 red porgy collected in 

 Onslow Bav, N.C. 



In Fecundity = 

 In Fecundity = 



1.7369 + 1.5178(ln Wt), 

 r2 = 0.70 and 

 -14.1325 + 4.3598(ln TL), 

 r~ = 0.66. 



Fecundity 



Regression analyses indicated total length, 

 weight, or age could be used to predict fecundity of 

 red porgy, but weight proved to be the best 

 predictor of fecundity (r- = 0.70) and had the 

 lowest error mean square. Combinations of two 

 independent variables, weight and length, im- 

 proved predictability only slightly, therefore, 

 separate equations were derived by using weight 

 on fecundity, and length on fecundity. The equa- 

 tions describing the relationships (Figure 3) and 

 coefficients of determination (r^) are: 



The 95% confidence limits have also been calculat- 

 ed. Predicted fecundity ranges from 48,660 eggs 

 for fish 304 mm TL and 390 g in weight to 488,600 

 ova for fish 516 mm TL and 1,783 g. Theoretically, a 

 600-mm red porgy which is not uncommon in the 

 sport catch, could produce approximately 943,000 

 eggs if maximum ova production is not obtained at 

 a smaller size. 



Sex Ratios and Hermaphroditism 



Sex of 736 red porgy collected in 1972, 1973, and 

 1974 was grouped by year and month, and data 



777 



