WARNER: REPRODUCTIVE BIOLOGY OF PIMELOMETOPON PULCHRUM 



those at Catalina. The growth rate is lower for 

 Guadalupe fishes and in both populations there 

 may be a slowing of growth at the onset of ma- 

 turity, as well as an increase in the growth rate 

 after sexual transformation. 



Pimelometopon pulchrum is a protogynous her- 

 maphrodite. During the sex change from female to 

 male, the ovary degenerates and spermatogenic 

 crypts dominate the gonad. The basic structure of 

 the gonad remains ovarian however, with lamellae 

 protruding into a central lumen. Sperm transport 

 is through a series of ducts on the periphery of the 

 gonad and oviduct. 



Catalina California sheephead attain sexual 

 maturity at age 4, at a standard length of about 

 200 mm. Most function as females for 4 yr and then 

 change sex, at a length of about 310 mm. Some 

 individuals may transform earlier or later, or not 

 at all. The Guadalupe population also matures at 

 age 4, at a length of about 140 mm. But transfor- 

 mation occurs at an earlier age, with most in- 

 dividuals becoming males by age 7. Peak trans- 

 formation activity occurs in fishes between 190 

 and 230 mm SL at Guadalupe. 



Gonad development states and gonad indices of 

 Catalina California sheephead suggest that 

 spawning occurs in July, August, and September 

 and that sexual transformation occurs in the 

 winter months between breeding seasons. 



Spawning probably takes place a number of 

 times in a single breeding season, which 

 complicates the determination of the actual 

 number of eggs produced by a female each year. 

 Ovary weight, however, can give a good indication 

 of relative age and size-specific fecundities, since 

 egg density does not appear to vary with fish 

 length. The ovary weight of P. pulchrum increases 

 exponentially with length and linearly with the 

 age of the individual in the Catalina population. 



At Guadalupe, the average fecundity probably 

 increases more slowly with age when compared to 

 Catalina, due to the low average rate of growth. 



Pimelometopon pulchrum has three color 

 phases. Juvenile coloration occurs in individuals 

 usually less than a year old and smaller than 100 

 mm in length, and never in sexually mature in- 

 dividuals. 



The uniform coloration is found in immatures 

 and mature females. Melanization may obscure 

 the ground coloration, but it appears that about 5% 

 of the mature uniform individuals were males at 

 Catalina, and 12% at Guadalupe. 



Bicolored fishes are exclusively males or late 



transitionals and usually have a nuchal hump and 

 filamentous extensions of the median fins. 



Field observations indicate that there are about 

 5.5 uniformly colored individuals to every 

 bicolored male at both Catalina and Guadalupe. 



Individual size appears to have a greater effect 

 on the sex change than does age, and rapidly 

 growing fishes may change sex sooner than slow 

 growing individuals of the same age, which may 

 not change sex at all. 



With the assumption of constant, age-indepen- 

 dent mortality, the annual survival rate at both 

 Catalina and Guadalupe was estimated as about 

 0.7, as judged from the field transect data. 



The mature sex ratio at Catalina was 

 approximately two females for every male. At 

 Guadalupe the ratio was closer to three females for 

 every two males, due in part to the earlier sexual 

 transformation seen there. 



ACKNOWLEDGMENTS 



I would like to particularly thank R. H. 

 Rosenblatt and E. W. Fager for their early and 

 continued encouragement and advice. I am also 

 grateful to J. T. Enright, P. K. Dayton, and J. B. 

 Graham for their critical comments on an earlier 

 draft. Special thanks go to Isabel Downs for her 

 help in many phases of this project. Finally, I 

 would like to thank D. R. Diener for many 

 stimulating discussions on the fascinating field of 

 hermaphroditism in fishes. 



LITERATURE CITED 



Atz.J.W. 



1964. Intersexuality in fishes. In C. N. Armstrong and A. J. 

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 ing man, p. 145-232. Academic Press., Lond. 

 Barnhart, p. S. 



1936. Marine fishes of southern California. Univ. Calif. 

 Press, Berkeley, 209 p. 



BODMER, W. F., AND A. W. F. EDWARDS. 



1960. Natural selection and the sex ratio. Ann. Hum. Genet. 

 24:239-244. 

 BoLiN, R. L. 



1930. Embryonic development of the labrid fish Oxyjulis 

 califomicus Gunther. Copeia 1930(4): 122- 128. 

 Breder, C. M., Jr., and D. E. Rosen. 



1966. Modesof reproduction in fishes. Natural History Press, 

 Garden City, N.Y., 941 p. 



Chan, S. T. H. 



1971. Natural sex reversal in vertebrates. Philos. Trans. R. 

 Soc. Lond., Ser. B, Biol. Sci. 259:59-71. 

 Chan, S. T. H., A. Wright, and J. G. Phillips. 



1967. The atretic structures in the gonads of the rice-field 



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