FISHERY BULLETIN: VOL. 74, NO. 4 



Figure 5.- Young red porgy, 18 mm total length, collected by trawl off Charleston, S.C, in April 1974 (drawing by Herbert Gordy, 



National Marine Fisheries Service, NOAA). 



observed which had ovaries containing absorbed 

 ova during the peak spawning period. 



Fecundity estimation for red porgy ranged 

 from 48,656 eggs for a 304-mm female to 488,600 

 ova for a 516-mm fish. Larger fish (>600 mm TL), 

 which occasionally appear in the sport fishery, may 

 produce over 900,000 eggs. Eggs removed from 

 ripe females ranged in size from 0.31 to 0.94 mm in 

 diameter. The developed P. pagrus eggs averaged 

 0.88 mm in diameter and contained a single oil 

 droplet averaging 0.25 mm in diameter. While 

 fecundity was correlated to three predictors; 

 length, weight, and age, weight was the most 

 accurate predictor of fecundity. Although age was 

 not as satisfactory a predictor of fecundity as 

 weight and length, it should not be overlooked, 

 because the age-fecundity relation can have useful 

 application in population modeling. High vari- 

 ability in fecundity estimates for age-groups is 

 expected due to range in size and variation in 

 gonad size among fish of the same size (Bagenal 

 1967). 



Sex ratios for red porgy were usually un- 

 balanced in favor of females. Analyzing data by 

 month, year, and size, I observed a domination by 

 females. The overall sex ratio observed was 1:2. 

 The occurrence of females was higher during the 

 spawning season. This predominance may be 



attributed to difference in feeding behavior of ripe 

 fish, or to true population differences in the areas 

 sampled. I do not believe gear selectivity 

 influenced sex ratios. The dominance of females 

 for the smaller size classes and actual documenta- 

 tion of hermaphroditic red porgy in the study 

 lends some support to the theory of protogynous 

 hermaphroditism reported for the species in the 

 Gulf of Mexico (Beaumariage pers. commun.). 

 Both protandrous and protogynous hermaphrodi- 

 tism are relatively common among the sparids 

 (D'Ancona 1950, 1956). Although only 2% of the fish 

 examined were obviously hermaphroditic, a com- 

 plete histological study of gonadal development is 

 needed to determine if the species displays sex 

 reversal. Protogynous hermaphroditism may have 

 selective advantages as Atz (1964:224) mentioned 

 providing an endocrinologically better balanced 

 fish, assuring presence of both sexes in isolated, 

 insular areas, or a mechanism of population con- 

 trol. For the latter purpose, certain population 

 pressures presumably stimulate sexual transition. 

 Probably more applicable to red porgy hermaph- 

 roditism is the "size advantage model" proposed 

 by Ghiselin (1969). The theory explains sequential 

 hermaphroditism as occurring when an organism 

 reproduces more efficiently as one sex when small 

 and the opposite sex when larger. A male's poten- 



780 



