826 



Fishery Bulletin 101(4) 



300-350 351-400 401-450 451-500 501-550 551-600 

 Size class (mm) 



Figure 3 



Size-frequency distribution of female striped mullet used in fecundity determinations from 

 South Carolina estuaries from 1998 to 2000. n (number offish in sample) = 50 fish for 1998, 

 ri = 37 for 1999. and n = 42 for 2000. 



subsample. The overall mean oocyte diameter for each 

 specimen resulted from the calculated average of the 

 means of the three subsamples. Measurements were not 

 made on fresh oocytes but shrinkage was estimated from 

 the amount of whole ovary shrinkage because fresh ovary 

 weight and preserved (in 10% formalin) ovary weight were 

 known. The estimated unpreserved oocyte diameter was 

 determined by multiplying the preserved oocyte diameter 

 by 1 and adding the percentage of ovary shrinkage. The dif- 

 ference in the preserved oocyte diameter and the estimated 

 fresh oocyte diameter was then compared by using a paired 

 t-test to determine if there was a significant difference be- 

 tween preserved and unpreserved oocyte diameters. 



Age was determined by using the left sagittal otolith, 

 which was embedded in epoxy resin. A 0.5-mm transverse 

 section encompassing the otolith core was cut with an 

 Isomet low-speed saw with diamond wafering blades. The 

 thin section of the otolith was embedded in epoxy and ob- 

 served with a dissection microscope at the magnification 

 appropriate for the otolith's size. Age was recorded as the 

 number of rings (annular bands) present. The otoliths were 

 initially aged by one reader. A second reader then evalu- 

 ated a subsample of specimens from 1998 and 2000 and all 

 the otoliths from 1999. Ages were validated by the percent- 

 age of agreement between the two age determinations, an 

 analysis of variance (ANOVA) between the two groups of 

 ages, and a paired Mest comparing the means and vari- 

 ances of the two groups (Campana et al., 1995). 



Results 



Fecund female striped mullet (again, defined as those 

 females with ovaries containing oocytes >4G0 ^m in the 

 tertiary stage of vitellogenesis) were collected from late 

 October through February; most of the specimens were 

 caught in November and December for all three years. 

 Size-frequency distributions did not vary over the three 

 years of the study (Fig. 3). Fewer fish (n=37) were taken in 

 1999 versus 1998 (n=50) and 2000 (/i=42). The most abun- 

 dant size class for each year was that from 401 to 450 mm. 

 In the overall size-frequency distributions, fecund females 

 made up greater than 44% of those fish larger than 400 mm 

 in 1998 and comprised all of the specimens over 500 mm. 

 In 1999 the fecund females made up 12.5"% offish in the 

 401-450 mm size range, 39% of the fish in the 451-500 mm 

 size range, and 100% of the fish in the size classes over 500 

 mm. In 2000, fecund females made up 17.7% of the 401^50 

 mm size class, 35.7% in the 451-500 mm size range and, 

 like 1998 and 1999, all of the specimens over 500 mm. 



The majority of females used in our fecundity study 

 were 3 or 4 years old (Fig. 4), accounting for 80.0% of the 

 specimens in 1998 and 73.3% in 1999. However, the age 

 distribution in 2000 showed that the frequency of 2-, 3-, and 

 4-year-olds was the same and that these three ages made 

 up 82.0% of the fecund fish sampled that year. Three-year- 

 old fish made up the largest single group in 1998 and 1999. 

 The age determined from the otoliths was validated as part 



