Crabtree etal.: Reproduction of Albula vulpes 
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collected in the years during which we had regular 
monthly collections. 
Fecundity 
The total fecundity (the standing stock of advanced 
yolked oocytes) of 33 bonefish was estimated gravi- 
metrically. Ovaries were subsampled from anterior, 
middle, and posterior portions of each ovary to evalu- 
ate spatial variations in oocyte size within the ovary 
and between ovaries. Subsamples of ovary contain- 
ing 1,000-1,500 vitellogenic oocytes were weighed to 
the nearest 0.01 mg, and total fecundity was calcu- 
lated on the basis of the mean number of oocytes per 
gram of ovary. Ovaries that contained widespread 
atresia, which suggested that partial spawning might 
have occurred, were not used for fecundity estimation. 
Results 
Two of the bonefish that we examined were statisti- 
cally significant outliers (Crabtree et al., 1996); both 
were exceptionally small for their estimated ages and 
the weights of their otoliths were exceptionally light. 
Crabtree et al. excluded both fish from growth mod- 
els, age-frequency distributions, and otolith weight- 
age regressions, and we also excluded them from our 
analyses. One was a 351-mm female that was 7 years 
old and the other was a 458-mm female that was 18 
years old. Both fish were caught with hook-and-line 
gear on the ocean (Florida Straits) side of North Key 
Largo, and they were the smallest females examined 
whose ovaries contained vitellogenic oocytes. The 
458-mm female had oocytes that were in the nuclear 
migratory stage, and these were the most advanced 
oocytes we found in any bonefish. 
Length and age at sexual maturity 
Male bonefish reached 50% sexual maturity at a length 
of 418 mm (95% confidence interval 393-443 mm) and 
an age of 3.6 years (95% confidence interval 3. 3-3. 9 
years); females reached 50% sexual maturity at a length 
of 488 mm (95% confidence interval 472-504 mm) and 
an age of 4.2 years (95% confidence interval 3. 9-4. 6 
years; Fig. 2; Table 1). The lengths at 50% maturity 
(X 2 =124.43, df=l, P<0.001) and the ages at 50% matu- 
rity (% 2 =5.59, df=l, P=0.018) for males and females were 
significantly different. In addition, the overall logistic 
equations for length at 50% maturity (% 2 =51.18, df=2, 
P<0.001) and for age at 50% maturity (% 2 =11.55, df=2, 
P=0.003) for males and females were significantly dif- 
ferent. The smallest sexually mature male was 425 mm 
long, and the smallest sexually mature female was 358 
mm long. The youngest sexually mature male was 3 
years old, and the youngest sexually mature female 
was 2 years old. All males longer than 477 mm and all 
females longer than 594 mm were sexually mature. All 
males older than 5 years and all females older than 7 
years were sexually mature. 
Primary growth stage oocytes were present in all 
ovaries in which we counted oocytes (Fig. 3A). Corti- 
cal alveolar oocytes were present only in ovaries from 
fish longer than about 400 mm and older than 2 years 
and were common only in fish longer than about 475 
mm and older than 4 years (Fig. 3B). Vitellogenic 
oocytes were found only in fish longer than 450 mm 
and were common only in fish longer than 550 mm 
and older than 5 years (Fig. 3C). PAS-positive 
melanomacrophage centers were common only in 
females longer than about 550 mm and older than 5 
years (Fig. 3D): the same length and age as those for 
females that contained vitellogenic oocytes. 
Seasonality of gonad development 
Bonefish gonadal activity was seasonal. Vitellogenic 
oocytes were present in greatest numbers during No- 
vember-May, and their numbers declined during 
May-June (Fig. 4). There were no vitellogenic oocytes 
in any ovaries from females collected during August- 
September of any of the three summers during which 
we sampled. Cortical alveolar oocytes were present 
during all months but were least abundant during 
July-October. Primary growth stage oocytes were 
present in all females examined and made up at least 
20% of the total number of oocytes present. PAS-posi- 
tive melanomacrophage centers were most abundant 
in the gonads of spent and regressed males and fe- 
males and were most abundant in ovaries at the end 
of the spawning season in June-August (Fig. 5). They 
were least abundant in ovaries immediately before 
the initiation of spawning in November, when recru- 
descence was complete and most ovaries were ripen- 
ing to spawn during winter-spring. We saw no evi- 
dence of recent or imminent spawning, such as 
postovulatory follicles or fully hydrated females. Only 
six ovaries contained atretic hydrated oocytes, and 
no single histological preparation contained more 
than a few hydrated oocytes. 
Seasonal GSI patterns suggest that bonefish 
spawned during a prolonged period from November 
to June (Fig. 6). Median GSI’s were greatest during 
November-May and were least during July-Septem- 
ber. The decrease in female GSFs during July-Sep- 
tember corresponded with the decrease in the num- 
ber of vitellogenic oocytes present in ovaries and with 
the increased abundance of spent and regressed fish 
during late summer. 
