493
12 Species Case Studies
12.15.2 Reproduction
Spawning occurs in aggregations on reef fronts and passes although there is no
evidence that schools merge to achieve a larger mass of reproductive individuals
(Gladstone 1986 ; Hamilton et al. 2008 ) . Observations to date suggest most spawning occurs early in the day. Direct observation of reproductive activity by Purwanto
(Conservation Coordinator with the joint TNC-WWF Program Wakatobi) suggests
pair-spawning within schools. As with many large parrotfi shes there is no permanent pattern of sexual dichromatism although males adopt temporary colour signals
associated with spawning (Fig. 12.41 ). Histological evidence shows that the dominant sexual pattern of B. muricatum is gonochorism with high incidences of anatomical but non-functional hermaphroditism. B. muricatum also differs from most
other parrotfi shes in that all males pass through an immature female phase with the
developing gonad being morphologically female (Sadovy de Mitcheson and Liu
2008 ) . Adult testes retain the ex-ovarian lumen and peripheral sperm sinuses in the
gonad wall. It is presently unclear if sex reversal occurs at any point in the geographical range of this widespread species (Hamilton et al. 2008 ) .
12.15.3 Fisheries and Conservation
Coral reef fi sheries target this species over its entire range, the exceptions being
marine reserves and areas remote from human habitation. Although spawning occurs
in groups there is little evidence that reproductive aggregations are the primary target
for fi shers. Fishing practices tend to be ocean-specifi c. Western Pacifi c fi shers usually employ nocturnal diving to target schools sleeping in shallow water on reef
fronts and passes. Some harvesting, especially in Indonesia, is based on daylight
spearing with sale in local markets (Fig. 12.42 ). At Indian Ocean sites such as the
Cocos-Keeling Islands, using large nets to surround schools feeding in shallow water
is the method of choice. Some netting occurs in Melanesia but this is relatively
uncommon and represents a more traditional approach before the availability of
masks and underwater illumination. By focusing on schooling behaviour as well as
the shallow foraging and sleeping depth range all methods can result in large catches
of adults over short time periods. Nocturnal spearing on SCUBA allows for the greatest catches as an entire school may be harvested in a single fi shing episode.
The species is marked fresh and chilled. It does not occur in the live reef fi sh
trade, possibly a refl ection of the extreme diffi culty in maintaining this species in
captivity (Hamilton 2004 ) . B. muricatum is represented in local markets at a large
number of locations over the geographic range including Jedda (Red Sea), Indonesia
and New Caledonia. Given the large size and ease of return from netting and nocturnal spearing it is anticipated that harvests of relatively unexploited populations will
increase. The status of the fi shery in the western Pacifi c is instructive. In Papua New
Guinea and the Solomon Islands B. muricatum is heavily exploited by night spear
12 Species Case Studies
12.15.2 Reproduction
Spawning occurs in aggregations on reef fronts and passes although there is no
evidence that schools merge to achieve a larger mass of reproductive individuals
(Gladstone 1986 ; Hamilton et al. 2008 ) . Observations to date suggest most spawning occurs early in the day. Direct observation of reproductive activity by Purwanto
(Conservation Coordinator with the joint TNC-WWF Program Wakatobi) suggests
pair-spawning within schools. As with many large parrotfi shes there is no permanent pattern of sexual dichromatism although males adopt temporary colour signals
associated with spawning (Fig. 12.41 ). Histological evidence shows that the dominant sexual pattern of B. muricatum is gonochorism with high incidences of anatomical but non-functional hermaphroditism. B. muricatum also differs from most
other parrotfi shes in that all males pass through an immature female phase with the
developing gonad being morphologically female (Sadovy de Mitcheson and Liu
2008 ) . Adult testes retain the ex-ovarian lumen and peripheral sperm sinuses in the
gonad wall. It is presently unclear if sex reversal occurs at any point in the geographical range of this widespread species (Hamilton et al. 2008 ) .
12.15.3 Fisheries and Conservation
Coral reef fi sheries target this species over its entire range, the exceptions being
marine reserves and areas remote from human habitation. Although spawning occurs
in groups there is little evidence that reproductive aggregations are the primary target
for fi shers. Fishing practices tend to be ocean-specifi c. Western Pacifi c fi shers usually employ nocturnal diving to target schools sleeping in shallow water on reef
fronts and passes. Some harvesting, especially in Indonesia, is based on daylight
spearing with sale in local markets (Fig. 12.42 ). At Indian Ocean sites such as the
Cocos-Keeling Islands, using large nets to surround schools feeding in shallow water
is the method of choice. Some netting occurs in Melanesia but this is relatively
uncommon and represents a more traditional approach before the availability of
masks and underwater illumination. By focusing on schooling behaviour as well as
the shallow foraging and sleeping depth range all methods can result in large catches
of adults over short time periods. Nocturnal spearing on SCUBA allows for the greatest catches as an entire school may be harvested in a single fi shing episode.
The species is marked fresh and chilled. It does not occur in the live reef fi sh
trade, possibly a refl ection of the extreme diffi culty in maintaining this species in
captivity (Hamilton 2004 ) . B. muricatum is represented in local markets at a large
number of locations over the geographic range including Jedda (Red Sea), Indonesia
and New Caledonia. Given the large size and ease of return from netting and nocturnal spearing it is anticipated that harvests of relatively unexploited populations will
increase. The status of the fi shery in the western Pacifi c is instructive. In Papua New
Guinea and the Solomon Islands B. muricatum is heavily exploited by night spear