DeMartini et al.: Body sizes at maturation and at sex change, and spawning seasonality and sex ratio of Hyporthodus quernus 
131 
Diandrous species of epinephelines 
have been described ( Plectropomus 
leopardus and P. maculatus [Adams, 
2003]; Epinephelus coioides [Grand- 
court et al., 2009]; E. andersoni [Fen- 
nessy and Sadovy, 2002]; Cephalo- 
pholis boenak [Liu and Sadovy, 2004]; 
C. taeniops [Siau, 1994]) but seem 
to constitute a minority of species 
within the subfamily Epinephelinae. 
Diandry appears to be better repre- 
sented among small-bodied species 
and genera, whereas monandry ex- 
emplified by Hawaiian grouper is con- 
sistent with the general pattern for 
large-bodied groupers. Most known 
species of medium to large epineph- 
elid groupers also are aggregation- 
spawners (Samoilys and Squire, 1994; 
Sadovy et al., 1994), but nothing is 
known of the spawning habits of Ha- 
waiian grouper. Large (e.g., 7-12% 
[Erisman et al., 2007]) male GSIs are 
typical in groupers in which sperm 
competition occurs within multiple- 
male spawning aggregations. The 
relatively small (<1%) testes weights 
(compared to ovaries) of Hawaiian 
grouper are typical of protogynous 
species (Molloy et al., 2007) and in- 
dicate that it spawns in single-male 
spawning groups that lack intense 
sperm competition (Sadovy et al., 
1994). Although inconsistent with 
multiple-male spawning groups, rela- 
tively small testes size might reflect 
pair-spawning within aggregations 
and cannot be used as evidence either 
for or against aggregation spawning 
in the species (Domeier and Colin, 
1997). Growing evidence indicates 
that monandry and pair-spawning 
within aggregations are the norm for 
epinephelids that are large enough to 
migrate and can monopolize females 
while pair-spawning at low male den- 
sities. Diandry and multiple-male 
group-spawning is relatively preva- 
lent in smaller-bodied species that 
cannot tolerate the predation risk of 
migration to aggregation sites and 
that experience sperm competition at 
relatively high male densities. 
We caution that our evaluation of 
sex allocation patterns for Hawai- 
ian grouper is limited to fish in the 
NWHI. Other sex and gonadal allo- 
cation patterns may exist for popu- 
lations in the windward, high main 
Hawaiian Islands where, among other 
Figure 6 
Monthly gonadosomatic indices for female (top: solid circles and line) and 
male (bottom: hollow circles and coarse dashed line) Hawaiian grouper 
( Hyporthodus quernus). The mean gonadosomatic indices for females ( GSI F ) 
and males ( GSI M ) are indicated by medium and fine dashed lines, respec- 
tively. The number either above or below each data point indicates sample 
size (number of fish). Vertical lines represent 2 standard errors (SE). 
Month 
Figure 7 
Proportional monthly incidence of actively spawning female Hawaiian 
grouper (Hyporthodus quernus ) (i.e., those whose ovaries contained hydrated 
oocytes, postovulatory follicles, or both). The number above each histo- 
gram bar indicates sample size (number of fish). Vertical lines represent 
2 standard errors (SE). 
