502
12 Species Case Studies
females 15–25 cm length and while all had large, ripe ovaries, spawning was not
observed. The schools were not easily disturbed and Gladstone ( 1996 ) suggested
that this might be an example of the spawning stupor, where “this apparent ease
with which the longnose parrotfi sh were approached and captured is often observed
among schools of food fi shes that are preparing to spawn” (Johannes 1981 ) .
12.17 Striped Parrotfi sh – Scarus iserti , and Bullethead
Parrotfi sh – Chlorurus sordidus and Notes
on Other Small Parrotfi shes (Scaridae)
Patrick L. Colin
Coral Reef Research Foundation, PO Box 1765 , Koror , Palau 96940
e-mail: crrf@palaunet.com
12.17.1 General
The parrotfi shes (Scaridae) are abundant on reefs throughout the tropics. They are one
of the dominant groups of herbivores on reefs, converting benthic plant production
into fi sh biomass and then into vast amounts of spawning products which may be
exported from the reef as a result. All species produce planktonic eggs through both
pair- and group-spawning. Only a limited number of species are known to aggregate
for spawning, and all those are resident aggregations (Appendix). The numbers of
species with aggregating behaviour will surely rise as increased attention leads to new
records. Those small scarids which aggregate provide interesting comparisons between
family members of similar size as well as with the larger parrotfi shes. Some of the
larger species, such as the bumphead parrotfi sh, Bolbometopon muricatum , and longnose parrotfi sh, Hipposcarus longiceps , are being considered in separate case studies
(Chaps. 12.15 and 12.16 ). The striped parrotfi sh, Scarus iserti , in the western Atlantic
and the bullethead parrotfi sh, Chlorurus sordidus , in the Indo-west Pacifi c are excellent examples of small scarids and are probably the best known in their respective
regions. The females and initial phase males are similar in size (Fig. 12.47a, b ), and
both species have colourful terminal phase males (Fig. 12.47c ).
12.17.2 Reproduction and Aggregation
Small species are found in both the Indo-west Pacifi c and the Atlantic and have
similar patterns of both pair- and group-(aggregation) spawning. Scarids have both
adult “initial phase” fi sh, which can be female or male, and “terminal phase” males.
Initial phase fi sh generally group-spawn (and most should meet the defi nition of a
spawning aggregation) while terminal phase males pair-spawn with initial phase
12 Species Case Studies
females 15–25 cm length and while all had large, ripe ovaries, spawning was not
observed. The schools were not easily disturbed and Gladstone ( 1996 ) suggested
that this might be an example of the spawning stupor, where “this apparent ease
with which the longnose parrotfi sh were approached and captured is often observed
among schools of food fi shes that are preparing to spawn” (Johannes 1981 ) .
12.17 Striped Parrotfi sh – Scarus iserti , and Bullethead
Parrotfi sh – Chlorurus sordidus and Notes
on Other Small Parrotfi shes (Scaridae)
Patrick L. Colin
Coral Reef Research Foundation, PO Box 1765 , Koror , Palau 96940
e-mail: crrf@palaunet.com
12.17.1 General
The parrotfi shes (Scaridae) are abundant on reefs throughout the tropics. They are one
of the dominant groups of herbivores on reefs, converting benthic plant production
into fi sh biomass and then into vast amounts of spawning products which may be
exported from the reef as a result. All species produce planktonic eggs through both
pair- and group-spawning. Only a limited number of species are known to aggregate
for spawning, and all those are resident aggregations (Appendix). The numbers of
species with aggregating behaviour will surely rise as increased attention leads to new
records. Those small scarids which aggregate provide interesting comparisons between
family members of similar size as well as with the larger parrotfi shes. Some of the
larger species, such as the bumphead parrotfi sh, Bolbometopon muricatum , and longnose parrotfi sh, Hipposcarus longiceps , are being considered in separate case studies
(Chaps. 12.15 and 12.16 ). The striped parrotfi sh, Scarus iserti , in the western Atlantic
and the bullethead parrotfi sh, Chlorurus sordidus , in the Indo-west Pacifi c are excellent examples of small scarids and are probably the best known in their respective
regions. The females and initial phase males are similar in size (Fig. 12.47a, b ), and
both species have colourful terminal phase males (Fig. 12.47c ).
12.17.2 Reproduction and Aggregation
Small species are found in both the Indo-west Pacifi c and the Atlantic and have
similar patterns of both pair- and group-(aggregation) spawning. Scarids have both
adult “initial phase” fi sh, which can be female or male, and “terminal phase” males.
Initial phase fi sh generally group-spawn (and most should meet the defi nition of a
spawning aggregation) while terminal phase males pair-spawn with initial phase