419
12 Species Case Studies
are they found in other habitats, although they occasionally appear in seagrass beds
that are in close proximity to mangroves.
In southwest Florida juvenile goliath grouper migrate from mangrove nursery
habitats as they mature (Bullock et al. 1992 ; Koenig et al. 2007 ) and reach sizes
approaching 1,000 mm total length (TL), moving either to reefs in the immediate
offshore area, north toward the Florida Panhandle, or south through the Florida
Straits to the east coast of Florida (Koenig et al. 2007 ; CCK unpublished data). This
pattern is borne out by tag returns and regional diving surveys of adult goliath grouper abundance that suggests density-dependent factors as a mechanism driving
adults out from their centre of abundance. Adults re-enter mangrove habitats occasionally; this is one of few groupers known to venture into brackish waters as adults.
In Brazil, large juveniles and adults have also been observed in Fernando de Noronha
and Atol das Rocas, two offshore islands, where there are no mangrove formations
(Ferreira et al. 2006 ) . A shallow lagoon, at least in the case of Atol das Rocas, may
be a nursery area.
Both juveniles (Koenig et al. 2007 ) and adults (Sadovy and Eklund 1999 ;
Koenig et al. 2011 ) have limited home ranges, within which they exhibit some
degree of territoriality, displaying to intruders with an open mouth, quivering body
(Sadovy and Eklund 1999 ) , and a booming sound generated by contraction of muscles attached to the swim bladder (Mann et al. 2009 ) . The sound is apparently used
for intra- and inter-specifi c communication. Tagging studies have shown that individuals can move over 150 km. In adults most of these movements appear related
to travel to and from spawning sites or feeding sites. However, juveniles leaving
the mangroves may also move hundreds of km, apparently in response to densitydependent factors on offshore reefs (Koenig et al. 2011 ; Pina-Amargós and
González-Sansón 2009 ) .
12.4.3 Reproduction and Aggregation
Smith ( 1965 ) classifi ed all Epinephelus species as protogynous hermaphrodites.
However, neither goliath grouper nor Nassau grouper ( E. striatus ) (Sadovy and
Colin 1995 ) exhibit good evidence for functional hermaphroditism either in population or gonadal structure, based on criteria established by Sadovy and Shapiro
( 1987 ) and elaborated in Sadovy de Mitcheson and Liu ( 2008 ) . Although bisexuals
have been found in the goliath grouper population of the southeastern US (CCK and
FCC unpublished data), the nature of this hermaphroditic pattern is unknown as
neither the female – male sex ratio (ranging from 1.75:1 to 1:1) nor the size distribution is skewed. Indeed, small males occur in the population (Bullock and Smith
1991 ) . Further, goliath grouper exhibit no defi nitive sexual dimorphism in body
shape or colour (Bullock et al. 1992 ) , though Colin ( 1994 ) noted a presumed spawning colour pattern on presumed males. Size and age of sexual maturation are similar
between the sexes: male goliath grouper from the eastern Gulf of Mexico reach
sexual maturity by the time they reach 1,155 mm TL, with 50% mature by the age
12 Species Case Studies
are they found in other habitats, although they occasionally appear in seagrass beds
that are in close proximity to mangroves.
In southwest Florida juvenile goliath grouper migrate from mangrove nursery
habitats as they mature (Bullock et al. 1992 ; Koenig et al. 2007 ) and reach sizes
approaching 1,000 mm total length (TL), moving either to reefs in the immediate
offshore area, north toward the Florida Panhandle, or south through the Florida
Straits to the east coast of Florida (Koenig et al. 2007 ; CCK unpublished data). This
pattern is borne out by tag returns and regional diving surveys of adult goliath grouper abundance that suggests density-dependent factors as a mechanism driving
adults out from their centre of abundance. Adults re-enter mangrove habitats occasionally; this is one of few groupers known to venture into brackish waters as adults.
In Brazil, large juveniles and adults have also been observed in Fernando de Noronha
and Atol das Rocas, two offshore islands, where there are no mangrove formations
(Ferreira et al. 2006 ) . A shallow lagoon, at least in the case of Atol das Rocas, may
be a nursery area.
Both juveniles (Koenig et al. 2007 ) and adults (Sadovy and Eklund 1999 ;
Koenig et al. 2011 ) have limited home ranges, within which they exhibit some
degree of territoriality, displaying to intruders with an open mouth, quivering body
(Sadovy and Eklund 1999 ) , and a booming sound generated by contraction of muscles attached to the swim bladder (Mann et al. 2009 ) . The sound is apparently used
for intra- and inter-specifi c communication. Tagging studies have shown that individuals can move over 150 km. In adults most of these movements appear related
to travel to and from spawning sites or feeding sites. However, juveniles leaving
the mangroves may also move hundreds of km, apparently in response to densitydependent factors on offshore reefs (Koenig et al. 2011 ; Pina-Amargós and
González-Sansón 2009 ) .
12.4.3 Reproduction and Aggregation
Smith ( 1965 ) classifi ed all Epinephelus species as protogynous hermaphrodites.
However, neither goliath grouper nor Nassau grouper ( E. striatus ) (Sadovy and
Colin 1995 ) exhibit good evidence for functional hermaphroditism either in population or gonadal structure, based on criteria established by Sadovy and Shapiro
( 1987 ) and elaborated in Sadovy de Mitcheson and Liu ( 2008 ) . Although bisexuals
have been found in the goliath grouper population of the southeastern US (CCK and
FCC unpublished data), the nature of this hermaphroditic pattern is unknown as
neither the female – male sex ratio (ranging from 1.75:1 to 1:1) nor the size distribution is skewed. Indeed, small males occur in the population (Bullock and Smith
1991 ) . Further, goliath grouper exhibit no defi nitive sexual dimorphism in body
shape or colour (Bullock et al. 1992 ) , though Colin ( 1994 ) noted a presumed spawning colour pattern on presumed males. Size and age of sexual maturation are similar
between the sexes: male goliath grouper from the eastern Gulf of Mexico reach
sexual maturity by the time they reach 1,155 mm TL, with 50% mature by the age