482
12 Species Case Studies
Little is known of the habitats and life history of juveniles. The review by Sadovy
et al. ( 2003b ) reported juveniles above about 3 cm (Fig. 12.32a ) to occur in coral-rich
lagoon areas, thickets of branching Acropora corals, in sea grass beds, murky outer
river areas with patch reefs, shallow sandy areas adjacent to coral reef lagoons and in
shore mangrove and seagrass areas. Dorenbosch et al. ( 2006 ) reported juveniles from
2.5 to 27.5 cm TL (but most commonly 5–7.5 cm TL) in seagrass habitats, while on
coral reefs juveniles as small as 10 cm TL were rarely seen. Tupper ( 2007 ) considered coral-algal fl ats in Palau to be essential habitat for juveniles; however they also
occur in a variety of other reef habitats. Due to their cryptic nature they are often diffi cult to see and techniques, such as small rotenone stations (Smith-Vaniz et al. 2006 ) ,
would be needed to identify all types of habitats where they occur. There is a general
ontogenetic shift from more inshore habitats to the offshore reefs and deep reef
slopes where adults normally live (Sadovy et al. 2003b ) .
One acoustic tagging study in New Caledonia, using a single small probable
female (45 cm TL), found the fi sh remained near its tagging point for about 25 days,
then disappeared (Chateau and Wantiez 2007 ) . Since individuals can be recognized
by markings on head and body (e.g. Fig. 12.31a ), if the fi sh can be approached closely
enough to photographed, then a collection of identifi cation photos can be prepared.
12.13.4 Reproduction, Growth and Sexual Pattern
The humphead wrasse can live several decades and is a protogynous hermaphrodite.
Choat et al. ( 2006 ) has provided a demographic picture for the fi sh (Fig. 12.33 ) on
the Great Barrier Reef (GBR), using sagittal otoliths for ageing, where juveniles take
approximately 5 years to reach sexual maturity at about 35 cm standard length (SL).
At approximately 9 years and 65 cm SL, or above, some females change sex to males.
Remaining females continued to grow but did not exceed about 90 cm, or 32 years.
Males grow faster, reaching lengths of 1.5 m but were not found to reach more than
about 25 years in age. Specimens examined from Indonesia, GBR and Papua New
Guinea, fi eld observations in Palau and Malaysia, and minimum size for females to
spawn in captivity in Indonesia indicate that fi rst female sexual maturation typically
occurs between about 40 and 50 cm TL (Sadovy et al. 2003b ; Colin 2010 ; Sadovy de
Mitcheson et al. 2010 ; Steve Oakley unpublished data). Being protogynous, most
males develop by the sex change of functional females, although a few males appear
to develop directly from the juvenile stage (Sadovy et al. 2003 b ) .
Humphead wrasse spawn in aggregations which have been confi rmed in the
South China Sea off Sabah, Malaysia, the Great Barrier Reef and Palau (detailed in
Colin 2010 ) . It is a resident aggregator, somewhat surprising since most other large
reef fi shes that aggregate, such as groupers, have transient aggregations. When
ready to spawn, males display themselves above the reef in a courtship posture with
the anal fi n pointed, the caudal fi n scissored closed and the dorsal fi n close to the
body (Fig. 12.34 ). The face becomes blue in males and the head markings become
12 Species Case Studies
Little is known of the habitats and life history of juveniles. The review by Sadovy
et al. ( 2003b ) reported juveniles above about 3 cm (Fig. 12.32a ) to occur in coral-rich
lagoon areas, thickets of branching Acropora corals, in sea grass beds, murky outer
river areas with patch reefs, shallow sandy areas adjacent to coral reef lagoons and in
shore mangrove and seagrass areas. Dorenbosch et al. ( 2006 ) reported juveniles from
2.5 to 27.5 cm TL (but most commonly 5–7.5 cm TL) in seagrass habitats, while on
coral reefs juveniles as small as 10 cm TL were rarely seen. Tupper ( 2007 ) considered coral-algal fl ats in Palau to be essential habitat for juveniles; however they also
occur in a variety of other reef habitats. Due to their cryptic nature they are often diffi cult to see and techniques, such as small rotenone stations (Smith-Vaniz et al. 2006 ) ,
would be needed to identify all types of habitats where they occur. There is a general
ontogenetic shift from more inshore habitats to the offshore reefs and deep reef
slopes where adults normally live (Sadovy et al. 2003b ) .
One acoustic tagging study in New Caledonia, using a single small probable
female (45 cm TL), found the fi sh remained near its tagging point for about 25 days,
then disappeared (Chateau and Wantiez 2007 ) . Since individuals can be recognized
by markings on head and body (e.g. Fig. 12.31a ), if the fi sh can be approached closely
enough to photographed, then a collection of identifi cation photos can be prepared.
12.13.4 Reproduction, Growth and Sexual Pattern
The humphead wrasse can live several decades and is a protogynous hermaphrodite.
Choat et al. ( 2006 ) has provided a demographic picture for the fi sh (Fig. 12.33 ) on
the Great Barrier Reef (GBR), using sagittal otoliths for ageing, where juveniles take
approximately 5 years to reach sexual maturity at about 35 cm standard length (SL).
At approximately 9 years and 65 cm SL, or above, some females change sex to males.
Remaining females continued to grow but did not exceed about 90 cm, or 32 years.
Males grow faster, reaching lengths of 1.5 m but were not found to reach more than
about 25 years in age. Specimens examined from Indonesia, GBR and Papua New
Guinea, fi eld observations in Palau and Malaysia, and minimum size for females to
spawn in captivity in Indonesia indicate that fi rst female sexual maturation typically
occurs between about 40 and 50 cm TL (Sadovy et al. 2003b ; Colin 2010 ; Sadovy de
Mitcheson et al. 2010 ; Steve Oakley unpublished data). Being protogynous, most
males develop by the sex change of functional females, although a few males appear
to develop directly from the juvenile stage (Sadovy et al. 2003 b ) .
Humphead wrasse spawn in aggregations which have been confi rmed in the
South China Sea off Sabah, Malaysia, the Great Barrier Reef and Palau (detailed in
Colin 2010 ) . It is a resident aggregator, somewhat surprising since most other large
reef fi shes that aggregate, such as groupers, have transient aggregations. When
ready to spawn, males display themselves above the reef in a courtship posture with
the anal fi n pointed, the caudal fi n scissored closed and the dorsal fi n close to the
body (Fig. 12.34 ). The face becomes blue in males and the head markings become