GRIMES and HUNTSMAN: REPRODUCTIVE BIOLOGY OF THE VERMILION SNAPPER 



Table l. — Analysis of variance testing the hypothesis that 

 there is no difference in ovum diameters between anterior, pos- 

 terior, and center sections of ovaries from three vermilion snap- 

 per. NS = not significant. 



nal ova samples (total sample minus counting 

 subsample) were drained and dried for 24 h at 40° 

 C. Subsample and original ova sample dry weights 

 were determined to 0.001 g on a beam balance, and 

 the sum of these two weights provided the total 

 ova sample dry weight. Fecundity was determined 

 by proportionality where: 



fecundity 



total ova dry weight 



number of ova in subsample 

 subsample dry weight 



Fecundity models were fitted by semilog transfor- 

 mation (log fecundity = a + 6 x length, weight, or 

 age) and regressions are the functional regres- 

 sions of Ricker (1973). The semilog formulation of 

 fecundity models was used instead of more tradi- 

 tional log-log models because they fit the data 

 best. 



RESULTS 



Seasonality, Frequency, and 

 Duration of Spawning 



Several lines of evidence indicate that spawning 

 occurs from late spring through early fall. Males 

 and females with ripe-appearing gonads were col- 

 lected from late April through September, but few 



females were collected with ova loose within the 

 ovarian tunic. Microscopic examination of pre- 

 served ovaries showed three types of maturing ova 

 present during this period (in addition to matur- 

 ing ova, undifferentiated transparent oocytes 

 were present and were by far the most numerous): 

 the smallest developing ova (0.11-0.2 mm in 

 diameter) were translucent and were the most 

 numerous developing type; the next largest ova 

 (0.33-0.43 mm in diameter) were nearly opaque 

 throughout and less abundant than the preceding; 

 the largest developing ova (0.46-0.71 mm in 

 diameter) were typical mature teleost eggs with 

 opaque cytoplasm occupying one pole of the egg 

 which also contained transparent to translucent 

 yolk material and oil globules. We observed these 

 most mature ova only in ovaries collected from 

 May to September, although what appeared to be 

 ripe ovaries were also seen in April; furthermore, 

 these mature ova occurred in only 7 of 149 ripe- 

 appearing ovaries examined. 



Frequency distributions of maturing ovum 

 diameters (Table 2) show at least two size modes of 

 ova present from April to October (three were pre- 

 sent in one of two June samples), while only one 

 smaller size mode or undifferentiated oocytes were 

 present in November, December, and March. No 

 ova collected in January or February were 

 examined. These data indicate spawning begins in 

 late April or May and continues through Sep- 

 tember or perhaps early October. 



Monthly mean gonad index values for 101 sexu- 

 ally mature females, sampled from May 1972 to 

 April 1974, also denote late spring to fall spawn- 

 ing (Figure 2). No fish were collected in January or 

 February 1973 or 1974; however, adult females 

 collected in February 1975 had gonad index values 

 of 0.51 and 0.40 which are consistent with gonad 

 index trends indicated in Figure 2. Increasing 



Table 2. — Developing ovum diameter-frequency distributions (percent) from two female vermilion snapper that were examined 



during various months of the study. 



139 



