735 
Abstract .—We examined 1 166 black 
grouper ranging from 155 to 1518 mm 
TL collected in South Florida waters 
from 1994 to 1996. Among all black 
grouper that we sexed, females ranged 
from 155 to 1310 mm in length (mean= 
696, /t= 834), and males ranged from 
947 to 1518 mm (mean=1255, n=54). 
Ages of 927 black grouper ranging from 
155 to 1518 mm TL were estimated 
from thin-sectioned otoliths (sagittae). 
Marginal-increment analysis of grou- 
per 1-7 years old suggested that a 
single annulus was formed each year 
during May-June. Black grouper ap- 
pear to reach a maximum age of at least 
33 years, but ages of fish older than 7 
years are unvalidated. Growth of the 
black grouper in our study was rapid 
until an age of about 10 years and then 
slowed considerably. The von Berta- 
lanffy growth equation for black grou- 
per was TL = 1306.21 l-e(-o.i69C^ e+ o.768)))_ 
Black grouper are protogynous her- 
maphrodites. We estimated that 50% of 
the females in the population had 
reached sexual maturity by 826 mm 
and an age of 5.2 years. By a length of 
1214 mm and an age of 15.5 years, 50% 
of the females in our sample had trans- 
formed into males. The presence of 
large females in the population sug- 
gests that some females may not trans- 
form into males. The scarcity of transi- 
tional grouper 1/7 = 1) in our sample sug- 
gests that transition occurs quickly. 
Black grouper appear to spawn year- 
round, but peak spawning occurs dur- 
ing winter and early spring. Vitel- 
logenic oocytes and oocytes in the final 
stages of maturation were most com- 
mon during January-March. 
Manuscript accepted 4 February 1998. 
Fishery Bulletin 96:735-753 (1998). 
Age, growth, and reproduction of 
black grouper, Mycteroperca bonaci, 
in Florida waters 
Roy E. Crabtree 
Lewis H. Bullock 
Florida Marine Research Institute, Department of Environmental Protection 
100 Eighth Avenue SE, St. Petersburg, Florida 3370 1 -5095 
E-mail address (for R. E. Crabtree), crabtree_r@epic7.dep. state. fl.us 
The black grouper, Mycteroperca 
bonaci, is a large, piscivorous 
epinepheline serranid that inhabits 
coral reefs and rocky ledges from 
North Carolina to Florida, in the 
Gulf of Mexico, off Bermuda, in the 
West Indies, and from Central 
America to southern Brazil (Smith, 
1971; Bullock and Smith, 1991). The 
black grouper supports important 
commercial and recreational fisher- 
ies in South Florida. Commercial 
landings of the species consistently 
exceed landings of any other grou- 
per in the Florida Keys. Statewide, 
the estimated value of Florida black 
grouper commercial landings has 
decreased from $2.7 million in 1990 
to $1.1 million in 1996 (Florida De- 
partment of Environmental Protec- 
tion Marine Fisheries Information 
System 1 ). 
Florida imposes both recreational 
and commercial regulations on 
black grouper caught in state wa- 
ters. There is a recreational mini- 
mum size limit of 20 inches (508 
mm) total length (TL) and an ag- 
gregate daily bag limit of five grou- 
pers, including black, yellowfin 
(Mycteroperca venenosa), gag (M. 
microlepis), red (Epinephelus morio), 
yellowmouth (M. inter stitialis), and 
scamp (M. phenax ). The commercial 
minimum size limit is also 20 inches 
TL. Federal regulations include a 
20-inch minimum size limit and an 
annual quota for the shallow-water 
grouper complex, which includes 
the black grouper. In addition, the 
activities of commercial longline 
fishermen east of Cape San Bias, 
Florida (85°22'W), are restricted to 
depths greater than 20 fathoms. 
Even though the black grouper 
fishery is regulated in both state 
and federal waters, little is known 
about the species’ biology, and ex- 
isting data are inadequate to evalu- 
ate the effect of fishing mortality on 
populations. Like most grouper spe- 
cies, black grouper are protogynous 
hermaphrodites (Garcia-Cagide and 
Garcia, 1996). Hermaphroditic spe- 
cies may respond differently to fish- 
ing mortality than typical gono- 
choristic species do, and in some 
situations, protogynous herma- 
phrodites may be more sensitive to 
overfishing than gonochorists (Ban- 
nerot et al., 1987). For example, 
size-selective fishing mortality can 
greatly skew population sex ratios 
towards females, which may affect 
spawning success. In addition, 
many grouper species form large 
spawning aggregations that can be 
easily overfished (Sadovy, 1994). 
Only Manooch and Mason (1987) 
have specifically addressed black 
1 Florida Dep. Environmental Protection 
Marine Fisheries Information System. 
1997. Florida Marine Research Inst., 
Florida Dep. Environmental Protection, 
100 Eighth Ave. SE, St. Petersburg, 
Florida 33701-5095. 
