450
12 Species Case Studies
12.9.1 General
The leopard coralgrouper, Plectropomus leopardus (Lacepède 1802), also known in
English as coral trout and leopard grouper, is distributed in the western Pacifi c from
southern Japan to southern Queensland, west to Lombok, Indonesia and Western
Australia, and east to Caroline Islands and Fiji. It occurs at depths of 3–100 m
(Heemstra and Randall 1993 ) .
The leopard coralgrouper is a medium-sized diurnally active grouper easily
observed underwater, therefore vulnerable to spear fi shing but also amenable to
accurate visual census surveys (Samoilys and Carlos 2000 ) . Biological parameters
for the leopard coralgrouper, listed in Table 12.2 , are largely from studies conducted
on the Great Barrier Reef (GBR), Australia. The leopard coralgrouper grows rapidly in the fi rst 2–3 years of life, and matures relatively early for a grouper
(Table 12.2 ). The juvenile diet consists largely of benthic crustaceans, but this shifts
just prior to maturity to a piscivorous diet (St John 1999 ) . Recruitment of juveniles
appears to be largely driven by current patterns and geomorphology (Doherty et al.
1994 ) . Leopard coralgrouper larvae have been reared experimentally from eggs and
sperm sourced from spawning aggregations on the GBR (Rimmer et al. 1994 ) ,
Japan, and elsewhere in Southeast Asia, with commercial scale production recently
reported from Hainan Island, Mainland China; no data are available on production
and there are problems in ensuring the red body colouration in cultured fi sh (Yvonne
Sadovy de Mitcheson, personal communication).
12.9.2 Reproductive Biology
The leopard coralgrouper is a protogynous hermaphrodite, maturing as female
fi rst at 2–3 years changing to male at around 7 years. Females are batch spawners,
on average spawning 28 times per year (Table 12.2 ), with a high annual fecundity
compared with other serranids (Sadovy 1996 ) . From studies on the northern GBR
the leopard coralgrouper is known to form well-defi ned, temporally predictable
spawning aggregations at the same sites over decades (Samoilys 1997 ; Samoilys
et al. 2001 ) . Aggregations form for a 5 day period around the new moon over 3
months, September to November. Males display distinctive spawning colouration
(Fig. 12.17 ) and control territories of 50–250m
2 where they pair-spawn. A small
group of moderate sized individuals at the periphery of the aggregation appeared
to be males but were not observed to court. However in one pair-spawning a single
smaller male streaked into the egg cloud and released sperm. Pair-spawning in
aggregations is confi ned to a 30 min period at sunset. However, based on tagging
studies and estimates of leopard coralgrouper densities, only around 14% of individuals appear to participate in aggregation spawning (Samoilys 2000 ) . Further,
at least 50% of all spawnings may occur outside aggregations because a female
spawns on average 28 times a year, yet aggregations are only available for 15 days
12 Species Case Studies
12.9.1 General
The leopard coralgrouper, Plectropomus leopardus (Lacepède 1802), also known in
English as coral trout and leopard grouper, is distributed in the western Pacifi c from
southern Japan to southern Queensland, west to Lombok, Indonesia and Western
Australia, and east to Caroline Islands and Fiji. It occurs at depths of 3–100 m
(Heemstra and Randall 1993 ) .
The leopard coralgrouper is a medium-sized diurnally active grouper easily
observed underwater, therefore vulnerable to spear fi shing but also amenable to
accurate visual census surveys (Samoilys and Carlos 2000 ) . Biological parameters
for the leopard coralgrouper, listed in Table 12.2 , are largely from studies conducted
on the Great Barrier Reef (GBR), Australia. The leopard coralgrouper grows rapidly in the fi rst 2–3 years of life, and matures relatively early for a grouper
(Table 12.2 ). The juvenile diet consists largely of benthic crustaceans, but this shifts
just prior to maturity to a piscivorous diet (St John 1999 ) . Recruitment of juveniles
appears to be largely driven by current patterns and geomorphology (Doherty et al.
1994 ) . Leopard coralgrouper larvae have been reared experimentally from eggs and
sperm sourced from spawning aggregations on the GBR (Rimmer et al. 1994 ) ,
Japan, and elsewhere in Southeast Asia, with commercial scale production recently
reported from Hainan Island, Mainland China; no data are available on production
and there are problems in ensuring the red body colouration in cultured fi sh (Yvonne
Sadovy de Mitcheson, personal communication).
12.9.2 Reproductive Biology
The leopard coralgrouper is a protogynous hermaphrodite, maturing as female
fi rst at 2–3 years changing to male at around 7 years. Females are batch spawners,
on average spawning 28 times per year (Table 12.2 ), with a high annual fecundity
compared with other serranids (Sadovy 1996 ) . From studies on the northern GBR
the leopard coralgrouper is known to form well-defi ned, temporally predictable
spawning aggregations at the same sites over decades (Samoilys 1997 ; Samoilys
et al. 2001 ) . Aggregations form for a 5 day period around the new moon over 3
months, September to November. Males display distinctive spawning colouration
(Fig. 12.17 ) and control territories of 50–250m
2 where they pair-spawn. A small
group of moderate sized individuals at the periphery of the aggregation appeared
to be males but were not observed to court. However in one pair-spawning a single
smaller male streaked into the egg cloud and released sperm. Pair-spawning in
aggregations is confi ned to a 30 min period at sunset. However, based on tagging
studies and estimates of leopard coralgrouper densities, only around 14% of individuals appear to participate in aggregation spawning (Samoilys 2000 ) . Further,
at least 50% of all spawnings may occur outside aggregations because a female
spawns on average 28 times a year, yet aggregations are only available for 15 days