WARNER: REPRODUCTIVE BIOLOGY OF PIMELOMETOPON PULCHRUM 



Pimelometopon pulchrum (Ayres), the Califor- 

 nia sheephead, is a labrid of the subfamily 

 Bodianinae. It is confined to temperate waters, 

 ranging from Monterey Bay, Calif., to Cabo San 

 Lucas at the tip of Baja California, Mexico (Miller 

 and Lea 1972). Individuals can reach a large size 

 (over 800 mm standard length [SL]) and are com- 

 monly found off southern California along rocky 

 shores at depths betv^een 5 and 50 m. In this 

 report, it is demonstrated that P. pulchrum, like 

 many other labrids, is a protogynous her- 

 maphrodite. In addition, data are presented on age 

 and growth, on the distribution of the sexes in 

 relation to color, size, and age, and on the observed 

 patterns of fecundity and survival. The study 

 embraces two widely separated populations, 

 chosen to reflect how differences in the 

 demography of the population might lead to the 

 observed differences in the schedule of sexual 

 transformation (discussed in Warner in press). 



MATERIALS AND METHODS 



Source of Materials and 

 Times of Sampling 



Pimelometopon pulchrum was taken by means 

 of a hand spear while either skin diving or using 

 scuba. The main collecting area was at Fisher- 

 man's Cove on the northeast shore of Santa Cat- 

 alina Island, Calif., near the University of 

 Southern California Marine Station (lat. 33°27'N, 

 long. 118°29'W). A total of 341 individuals of P. 

 pulchrum were processed from samples taken the 

 year round at monthly intervals. Collections began 

 in December 1969 and continued, with occasional 

 gaps, until July 1971; monthly samples were 

 between 20 and 30 individuals. 



The other area sampled in this study was at 

 Guadalupe Island, Mexico, located approximately 

 200 km west of Punta Baja, Baja California. 

 Collections were made along the protected east 

 side of the island, concentrating on an area 3 km 

 from the southern tip known as Lobster Camp (lat. 

 29°01'N, long. 118°14'W). Year-round sampling at 

 Guadalupe Island was not possible, and the 130 

 individuals taken there were from three expedi- 

 tions, January 1970 (16 specimens), April 1970 (53 

 specimens), and May 1971 (61 specimens). 



Supplemental collections were made at La JoUa, 

 Calif., including a sample of large individuals from 

 a spearfishing meet on 19 July 1970. 



The standard length of each fish was measured. 



and its coloration noted. Several dorsal spines 

 were removed and frozen, and the gonads were 

 fixed in bouin's fluid. 



Age Determination Methods 



Age determination by counting annular marks 

 on the otoliths or scales was precluded in P. 

 pulchrum. The otoliths are extremely small and 

 difficult to locate, and the central portions of 

 nearly all the scales were either clear or irregularly 

 banded, indicating regeneration. 



The bones and spines of P. pulchrum did show 

 regular markings, and younger fish could be suc- 

 cessfully aged by counting the marks on either the 

 bones (opercula or cranial ridges) or the dorsal 

 spines. However, the proximal portions of the 

 bones tended to thicken and obscure the earlier 

 marks on older California sheephead and only 

 dorsal spine annuli could be used for age deter- 

 mination. 



Dorsal spines were prepared as follows: the flesh 

 was removed by means of a household enzyme 

 product (Ossian 1970) and the spines were air 

 dried. The classical methods of decalcification 

 and/or thin sectioning (e.g., Cuerrier 1951) were 

 not used. Instead, a high-speed grinding tool with 

 a thin abrasive disc was used to cut cleanly 

 through the spine at a point just distal to the 

 swollen portion of the base. The spinous portion 

 was then thrust through an opaque light shield so 

 that only the cut base protruded. A strong 

 microscope light was directed to the lower portion 

 of the shield so that the only light visible on the 

 other side then came through the projecting base 

 of the spine. The hyaline layers of the spine 

 transmit much more light and the illuminated 

 pattern, resembling tree rings, is easily seen in a 

 dissecting microscope. 



The second dorsal spine was used for primary 

 counts; the ring patterns on the other spines were 

 identical, and were used to verify counts for in- 

 dividuals. Counts on each spine were made by two 

 people and were used in the analysis of growth 

 only when they agreed. False rings, probably 

 caused by abnormal growth conditions, were 

 identifiable in young individuals by their 

 proximity to other annuli and their tendency to be 

 incomplete. 



Rarely, older fish showed a marked degenera- 

 tion of the central portion of the spine, which 

 became hollow and oil-filled, making age deter- 

 mination from spines impossible. 



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