THE REPRODUCTIVE BIOLOGY OF THE 

 PROTOGYNOUS HERMAPHRODITE PIMELOMETOPON PULCHRUM 



(PISCES: LABRIDAE) 



Robert R. Warner' 



ABSTRACT 



Pimelometopon pukhrum, California sheephead, a labrid fish of the eastern Pacific Ocean, was collected 

 the year round at Catalina Island, Calif., and comparative material was taken at Guadalupe Island, 

 Mexico. Individuals at Guadalupe were dwarfed relative to those at Catalina. Pimelometopon pukhrum 

 is a protogynous hermaphrodite, the ovarian elements undergoing massive degeneration as sperma- 

 togenic crypts proliferate in the gonads of transitional individuals. Sexual changes occur between 

 breeding seasons. Individuals from both populations mature as females at age four; most of those at 

 Catalina function as females for 4 yr and then change sex, at a length of around 310 mm. Sexual 

 transformation occurs earlier on the average at Guadalupe; most individuals are male by age seven. In 

 both populations, more rapidly growing fishes apparently change sex sooner than other individuals of 

 the same age, and fishes that grow slowly may not change sex at all. Spawning appears to occur in July, 

 August, and September in the Catalina population. Individuals probably spawn several times in a 

 breeding season. The weight of active, prespawning ovaries increases at a rate approximately propor- 

 tional to the third power of the length of the fish. Ovary weight increases in a linear fashion with age in 

 the Catalina population. The rate of increase with age would be less in the Guadalupe population due to 

 dwarfing. 



The three coloration phases of P. pulchrum are described, two of which are found in adult individuals. 

 The uniform coloration is made up mostly of mature female and immature fishes. About 5% of the 

 mature uniform individuals were males at Catalina, and about 12% at Guadalupe. The bicolored phase is 

 made up exclusively of males and late transitional individuals. Data from field transects revealed that 

 there were about five uniform individuals to every bicolored male. Based on an estimated yearly 

 survival rate of about 0.7, the mature sex ratio at Catalina was approximately two females for every 

 male. The ratio at Guadalupe was closer to three females for every two males, due in part to the earlier 

 sex changes seen there. 



Sequential hermaphroditism, a phenomenon 

 characterized by an individual changing from one 

 sex to another at some point in its life history, is 

 widespread in teleost fishes (Atz 1964; Reinboth 

 1970). In some species, individuals change from 

 male to female (protandry) and in others the sit- 

 uation is the reverse (protogyny). 



Most of the published information on the life 

 histories of sequentially hermaphroditic species 

 has dealt with the distribution of the sexes with 

 size, sometimes correlated with a histological 

 investigation of the gonads (Atz 1964; Reinboth 

 1970). However, in order to interpret the full 

 implications of the sexual patterns seen in 

 sequential hermaphrodites, data on the age dis- 

 tribution, age-specific fecundity, and the sexual 

 transformation schedule of the population are 

 needed (Warner in press). 



'Scripps Institution of Oceanography, University of Califor- 

 nia, San Diego, La JoUa, CA 92037; present address, Smithsonian 

 Tropical Research Institute, P.O. Box 2072, Balboa, Canal Zone. 



There are a few protogynous fish species for 

 which the information is nearly complete. For 

 example, Moe (1969) provided excellent data on the 

 life history pattern, gonadal transformation, and 

 survival rate of the serranid Epinephelus morio. 

 Natural sex reversal in the synbranchid 

 Monopterus albus has been extensively studied 

 both in the field and laboratory (Liem 1963, 1968; 

 Chan 1971), but little is known about its age- 

 specific fecundity and survival pattern. A similar 

 situation exists for the labrid Corisjulis (Reinboth 

 1957, 1962; Roede 1966), where again we lack infor- 

 mation on the demography of the population. 

 Among the Labridae, perhaps the most complete 

 information exists on the seven Caribbean species 

 of the genera Thalassoma, Halichoeres, and 

 Hemipteronotus studied by Roede (1972). An un- 

 fortunate limitation was placed on Roede's work 

 by the tropical location, which precluded age de- 

 termination from growth rings on scales or 

 otoliths. 



Manuscript accepted July 1974. 



FISHERY BULLETIN; VOL. 73, NO. 2, 1975. 



262 



