388 
The influence of spear fishing on 
species composition and size of 
groupers on patch reefs in the 
upper Florida Keys 
Robert D„ Sluka* 
Kathleen M. Sullivan 
Department of Biology, University of Miami 
Coral Gables, Florida 33 1 24 
and 
Florida and Caribbean Marine Conservation Science Center 
The Nature Conservancy 
PO. Box 249 1 1 8, Coral Gables, Florida 33 1 24 
*Present address: Oceanographic Society of Maldives 
PO. Box 2075, Male, Republic of Maldives 
E-mail address (for K. M. Sullivan, contact author): sullivan@benthos.cox.mlami.edu 
Groupers are an important fishery 
resource throughout tropical and 
subtropical regions of the world 
(Heemstra and Randall, 1993). De- 
pendent and independent fishery 
surveys of grouper populations in 
south Florida and the Caribbean 
have shown drastic declines in 
populations, most likely due to in- 
tense fishing pressure (Sadovy, 
1994; Bohnsack et ah, 1994). Com- 
bined grouper species landings by 
weight have declined in the Florida 
Keys by more than half since the 
mid 198Q’s (Bohnsack et al., 1994). 
Fishermen tend to target the 
larger fish in a population, with the 
result that a decrease in the den- 
sity, average size, and relative 
abundance of exploited species is 
inevitable (Bohnsack, 1982; Russ, 
1985; Plan Development Team 
(PDT), 1990; Roberts and Polunin, 
1991). Grouper populations are es- 
pecially sensitive to fishing pres- 
sure, exhibiting reductions in den- 
sity and average size, as well as 
shifts in species composition be- 
tween sites that are fished and 
those that are unfished (Russ, 
1985). For example, the mean 
weight of three species of grouper 
was found to be significantly greater 
in unfished than in fished sites in 
the Red Sea (Roberts and Polunin, 
1993). Similarly, the density and 
biomass of groupers was signifi- 
cantly greater in sites protected 
from fishing than in sites unpro- 
tected in the Philippines (Russ and 
Alcala, 1989). Craik (1981) found 
that a commercially important 
grouper ( Pleetropomus leopardus ) 
on the Great Barrier Reef had a 
higher mean size at an unfished 
reef than at a fished reef. Russ 
(1985) and Craik (1981) observed 
that larger individuals of a grouper 
species were abundant only at 
unfished reefs. Sluka et al. (1997) 
showed that the biomass, average 
size, and reproduction (the total 
number of eggs produced per hect- 
are) of Nassau grouper, Epinephelus 
striatus, was significantly greater 
inside a marine fishery reserve than 
outside. Many studies have attrib- 
uted a change in the relative abun- 
dance of grouper species to fishing 
pressure (Goeden, 1982; Bohnsack, 
1982; Russ, 1985; Watson and Or- 
mond, 1994; Sluka, 1995). 
In the Florida Keys there has 
been a history of management mea- 
sures that have affected fishing 
pressure on groupers. In 1980, the 
state of Florida banned fish traps 
in its waters (<3 nautical miles), 
and in 1992 the United States gov- 
ernment banned fish traps in fed- 
eral waters of the Florida Keys (>3 
nautical miles to the 150 fathom 
depth contour). During this study, 
there was a bag limit of five fish and 
a minimum size limit of 51 cm (20 
in.) for six grouper species (red 
grouper, Epinephelus morio, black 
grouper, Mycteroperca bonaci, 
yellowmouth grouper, M. inter- 
stitialis, gag, M. microlepis, scamp, 
M. phenax, and yellowfin grouper, 
M. venenosa). Harvest of two spe- 
cies (jewfish, E. itajara, in 1990 and 
Nassau grouper, E. striatus, in 
1991) has been prohibited in the 
south Atlantic waters of the United 
States. Reefs within Key Largo Na- 
tional Marine Sanctuary (KLNMS) 
and John Pennekamp Coral Reef 
State Park (JPCRSP) have been 
protected from spear fishing since 
1960. Since the time of this study, the 
entire Florida Keys has come under 
the management of the Florida Keys 
National Marine Sanctuary. 
One of the results of the previ- 
ous management scheme is that the 
upper Florida Keys can be divided 
into two areas: one area protected 
from spear fishing and the other 
unprotected from spear fishing. It 
is assumed that the intensity of 
hook-and-line fishing is similar in- 
side and outside of KLNMS and 
JPCRSP. Thus the goal of this study 
was to examine the influence of 
spear fishing on the size and spe- 
cies composition of groupers in the 
upper Florida Keys and to discuss 
potential implications for the man- 
agement of these populations. 
These population parameters were 
Manuscript accepted 19 August 1997. 
Fishery Bulletin 96:388-392 (1998). 
