492
12 Species Case Studies
Samoa are very low and substantially less than the fi shed areas of the Solomons and
PNG. In demographic terms this species is one of the longer lived parrotfi shes
achieving a maximum age of 40 years, and it shares a number of features with other
large members of the family. These include an indeterminate growth curve and thus
a relatively low growth coeffi cient (k) value, and a signifi cantly higher growth rate
in males although females achieve greater maximum ages. Female sexual maturation in Solomon Islands populations occurs at 7.5 ± 0.8 years (Fig. 12.40 ).
Size frequency estimates of B. muricatum populations on reef fronts which are
the preferred adult habitat are usually skewed towards the upper size ranges.
Juveniles and newly recruited individuals occur in sheltered lagoonal habitats and
inshore reefs with progressive colonization of more exposed habitats with increasing size (Aswani and Hamilton 2004 ) . The dependency on a sheltered lagoonal
environment is seen through comparisons of regional abundance patterns. Christmas
Island, an isolated Indian Ocean island with a fringing reef habitat and no local
fi shery for this species lacks a lagoonal habitat. This area has a very low abundance
of B. muricatum , only 3% of that recorded from an unfi shed reef system in the same
regional area (Rowley Shoals;16 per hectare) with a large area of juvenile habitat in
the form of lagoonal systems. There is also increasing evidence that this species is
more abundant on reefs associated with large islands and continental land masses as
opposed to ocean reefs surrounded by deep water.
0
200
400
600
800
1000
1200
1400
0
5
10
15
20
25
30
35
40
Size (Fork Length, mm)
Age (Years)
M
Fig. 12.40 Composite size-at-age plot by sexual identity for populations of Bolbometopon
muricatum. Individuals < 300 mm FL were collected from lagoon habitats Roviana, Solomon
Islands and lagoon habitats Cocos-Keeling Island. Mature individuals were collected from the
Solomon Islands and the Great Barrier Reef. Males denoted by squares, females by circles. M Age
at sexual maturity ±95% CI (From Hamilton et al. 2008 )
12 Species Case Studies
Samoa are very low and substantially less than the fi shed areas of the Solomons and
PNG. In demographic terms this species is one of the longer lived parrotfi shes
achieving a maximum age of 40 years, and it shares a number of features with other
large members of the family. These include an indeterminate growth curve and thus
a relatively low growth coeffi cient (k) value, and a signifi cantly higher growth rate
in males although females achieve greater maximum ages. Female sexual maturation in Solomon Islands populations occurs at 7.5 ± 0.8 years (Fig. 12.40 ).
Size frequency estimates of B. muricatum populations on reef fronts which are
the preferred adult habitat are usually skewed towards the upper size ranges.
Juveniles and newly recruited individuals occur in sheltered lagoonal habitats and
inshore reefs with progressive colonization of more exposed habitats with increasing size (Aswani and Hamilton 2004 ) . The dependency on a sheltered lagoonal
environment is seen through comparisons of regional abundance patterns. Christmas
Island, an isolated Indian Ocean island with a fringing reef habitat and no local
fi shery for this species lacks a lagoonal habitat. This area has a very low abundance
of B. muricatum , only 3% of that recorded from an unfi shed reef system in the same
regional area (Rowley Shoals;16 per hectare) with a large area of juvenile habitat in
the form of lagoonal systems. There is also increasing evidence that this species is
more abundant on reefs associated with large islands and continental land masses as
opposed to ocean reefs surrounded by deep water.
0
200
400
600
800
1000
1200
1400
0
5
10
15
20
25
30
35
40
Size (Fork Length, mm)
Age (Years)
M
Fig. 12.40 Composite size-at-age plot by sexual identity for populations of Bolbometopon
muricatum. Individuals < 300 mm FL were collected from lagoon habitats Roviana, Solomon
Islands and lagoon habitats Cocos-Keeling Island. Mature individuals were collected from the
Solomon Islands and the Great Barrier Reef. Males denoted by squares, females by circles. M Age
at sexual maturity ±95% CI (From Hamilton et al. 2008 )