456 
Maturation and reproductive 
seasonality in bonefish, Albula vulpes, 
from the waters of the Florida Keys 
Roy E. Crabtree* 
Derke Snodgrass 
Christopher W. Harnden 
Florida Marine Research Institute, Department of Environmental Protection 
100 Eighth Avenue SE, St. Petersburg, Florida 33701-5095 
*E-mail address: crabtree_r@sellers.dep.state.fl.us 
Abstract .—We examined 528 bone- 
fish to estimate length and age at 
sexual maturity and to describe sea- 
sonal patterns in gonadal development. 
These fish ranged from 21 to 702 mm 
fork length (FL) and were collected in 
South Florida waters from 1989 to 
1995. Gonads of 437 bonefish were ex- 
amined histologically, and gonado- 
somatic indices (GSI) were calculated 
for 449 bonefish. Male bonefish reached 
50% sexual maturity (the predicted size 
and age at which half the individuals 
are expected to be sexually mature) at 
418 mm FL (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 488 mm FL (95% confidence inter- 
val 472-504 mm) and 4.2 years (95% 
confidence interval 3. 9-4. 6 years). 
Lengths and ages at 50% maturity for 
males and females were significantly 
different. The smallest sexually mature 
male was 425 mm FL, and the small- 
est sexually mature female was 358 
mm FL. The youngest sexually mature 
male was 3 years old, and the youngest 
sexually mature female was 2 years old. 
Gonadal activity was seasonal and 
peaked during November-May. Vitel- 
logenic oocytes were present in ovaries 
in every month except August and Sep- 
tember and were most abundant dur- 
ing November-May. Median GSI’s were 
greatest during November-May and 
least during July-September for both 
males and females. No fully hydrated 
ovaries or postovulatory follicles were 
found, therefore we could not estimate 
spawning periodicity or batch fecundi- 
ties. Total fecundity ranged from 0.4 to 
1.7 million oocytes and had a signifi- 
cant positive relation to fish weight. 
The absence of fully hydrated ovaries 
and postovulatory follicles in the bone- 
fish we sampled suggests that bonefish 
spawn outside the traditional shallow- 
water (<2 m) fishing grounds in the 
Florida Keys. 
Manuscript accepted 17 January 1997. 
Fishery Bulletin 95:456-465 (1997). 
Bonefish, Albula spp., frequent 
coastal and inshore waters of tropi- 
cal seas worldwide and are the ba- 
sis of economically important re- 
creational fisheries in many areas 
of their range. Although 23 nomi- 
nal Albula species have been de- 
scribed (Whitehead, 1986), only two 
Atlantic species, A. vulpes and A. 
nemoptera, are recognized (Rivas 
and Warlen, 1967). In the western 
Atlantic, A. vulpes is common in the 
Florida Keys, the Bahama Islands, 
and throughout the Caribbean Sea 
(Hildebrand, 1963 ). Albula nemop- 
tera appears to have a more re- 
stricted distribution than A. vulpes 
and has been reported from the 
Guianas, Venezuela, Columbia, 
Panama, Jamaica, and Hispaniola 
(Rivas and Warlen, 1967; Uyeno et 
al., 1983). The single record of A. 
nemoptera from Florida waters is 
considered questionable (Robins 
and Ray, 1986), and the species has 
not been reported from the Bahama 
Islands (Bohlke and Chaplin, 1993). 
Bonefish are esteemed for their 
wariness and fighting abilities, and 
fishing for them provides an impor- 
tant source of income to Florida 
Keys and Bahamian fishing guides. 
Commercial sale of bonefish in 
Florida is prohibited, and regula- 
tions on the recreational fishery re- 
strict catches to one fish per angler 
per day and the length of captured 
fish to a minimum total length of 
457 mm (390 mm fork length). Most 
bonefish caught in Florida waters 
are released. 
The life history of bonefish has 
not been adequately described. 
Crabtree et al. (1996) described the 
age and growth of bonefish from 
South Florida and found that bone- 
fish can attain ages of 19 years. 
Female and male growth models 
were significantly different; females 
were slightly longer than males of 
the same age. Although the age and 
growth of Florida Keys bonefish 
have been studied, important ques- 
tions remain regarding bonefish 
reproduction. Bruger (1974) re- 
ported sexually mature females as 
small as 210 mm standard length 
(221 mm fork length) and as young 
as 1 year from waters off the Florida 
Keys, but his sample size was inad- 
equate to determine the age or 
length at 50% maturity (the pre- 
dicted size and age at which half the 
individuals are expected to be sexu- 
ally mature). Bruger found ripe fe- 
male bonefish throughout the year 
in waters off the Florida Keys and 
concluded that reproduction was 
not seasonal, but his sample size 
was small («=148) and his conclu- 
sions equivocal. In other areas, bone- 
fish reproduction appears to be sea- 
sonal according to patterns of lar- 
val and juvenile abundance (Alex- 
ander, 1961; Pfeiler, 1984; Pfeiler et 
al., 1988; Mojica et al., 1995). There 
