497
12 Species Case Studies
12.16.1 General
The longnose parrotfi sh Hipposcarus longiceps is a common medium-sized
parrotfi sh (maximum 60 cm SL) found from the Line and Tuamotu Islands throughout the tropical western Pacifi c and as far east as a few locations in the eastern
Indian Ocean. It is replaced by Indian Ocean longnose parrotfi sh, Hipposcarus
harid , in the remainder of the Indian Ocean. The adult initial phase males and
females are distinctive with a grey body and yellow caudal fi n. The terminal
phase males are generally light blue or green with a dark or light band in the
central area of the body. The juveniles are quite different in colour having a single
orange stripe.
This parrotfi sh occurs widely in reef environments, being found on inshore reefs
as well as offshore clear water reefs. They are herbivores, grazing rocky substrata
around reefs. They are superfi cially similar to the redfi n parrotfi sh, Sparisoma
rubripinne , of the western Atlantic both in colouration and behaviour. Little work
has been conducted on this species, most of it in Palau.
12.16.2 Aggregation and Spawning Behaviour
There has been very little published on the aggregation or courtship of the longnose
parrotfi sh. The closely related Indian Ocean longnose parrotfi sh has received more
attention (see below), but is still very poorly known. For Palau, Johannes ( 1981 )
recorded that a local knowledgeable fi sherman reported longnose parrotfi sh (as S.
harid ) to frequently aggregate at the extremities of underwater promontories on the
outer reef slope to spawn. Johannes ( 1981 ) also reports that in Pohnpei longnose parrotfi sh (again as S. harid ) spawns around the new moon in March, April and May.
Previously the only observations of spawning by longnose parrotfi sh were those
of Colin and Bell ( 1991 ) who reported pair-spawning in a tidal channel in April,
May and September at Enewetak Atoll. They did not observe aggregation or groupspawning. Longnose parrotfi sh generally spawned in the morning at Enewetak following high tide, however one pair-spawning was also seen on an oceanside reef
just after mid-day. There is also a record of aggregation spawning by longnose parrotfi sh from Canton Island (Stone 2004 ) , in a popular magazine article, which
reported aggregation spawning at Canton Island early in the morning by a group of
perhaps 5,000 individuals starting some time after 6:30 AM and continued for an
hour. Date and lunar phase were not specifi ed, although spawning was said to occur
on an outgoing tide.
New observations were made at Blue Corner, a promontory area of the western
barrier reef of Palau (Fig. 12.43 ), which is a popular tourist diving site due to the
regular presence of many sharks, other large fi shes and turtles. Longnose parrotfi sh
are often present at the site, but the numbers and occurrence of aggregation and
spawning are very incompletely documented. Observations of spawning were fi rst
brought to the attention of the author by Jim Forrest and Jeanette Denby of the yacht
12 Species Case Studies
12.16.1 General
The longnose parrotfi sh Hipposcarus longiceps is a common medium-sized
parrotfi sh (maximum 60 cm SL) found from the Line and Tuamotu Islands throughout the tropical western Pacifi c and as far east as a few locations in the eastern
Indian Ocean. It is replaced by Indian Ocean longnose parrotfi sh, Hipposcarus
harid , in the remainder of the Indian Ocean. The adult initial phase males and
females are distinctive with a grey body and yellow caudal fi n. The terminal
phase males are generally light blue or green with a dark or light band in the
central area of the body. The juveniles are quite different in colour having a single
orange stripe.
This parrotfi sh occurs widely in reef environments, being found on inshore reefs
as well as offshore clear water reefs. They are herbivores, grazing rocky substrata
around reefs. They are superfi cially similar to the redfi n parrotfi sh, Sparisoma
rubripinne , of the western Atlantic both in colouration and behaviour. Little work
has been conducted on this species, most of it in Palau.
12.16.2 Aggregation and Spawning Behaviour
There has been very little published on the aggregation or courtship of the longnose
parrotfi sh. The closely related Indian Ocean longnose parrotfi sh has received more
attention (see below), but is still very poorly known. For Palau, Johannes ( 1981 )
recorded that a local knowledgeable fi sherman reported longnose parrotfi sh (as S.
harid ) to frequently aggregate at the extremities of underwater promontories on the
outer reef slope to spawn. Johannes ( 1981 ) also reports that in Pohnpei longnose parrotfi sh (again as S. harid ) spawns around the new moon in March, April and May.
Previously the only observations of spawning by longnose parrotfi sh were those
of Colin and Bell ( 1991 ) who reported pair-spawning in a tidal channel in April,
May and September at Enewetak Atoll. They did not observe aggregation or groupspawning. Longnose parrotfi sh generally spawned in the morning at Enewetak following high tide, however one pair-spawning was also seen on an oceanside reef
just after mid-day. There is also a record of aggregation spawning by longnose parrotfi sh from Canton Island (Stone 2004 ) , in a popular magazine article, which
reported aggregation spawning at Canton Island early in the morning by a group of
perhaps 5,000 individuals starting some time after 6:30 AM and continued for an
hour. Date and lunar phase were not specifi ed, although spawning was said to occur
on an outgoing tide.
New observations were made at Blue Corner, a promontory area of the western
barrier reef of Palau (Fig. 12.43 ), which is a popular tourist diving site due to the
regular presence of many sharks, other large fi shes and turtles. Longnose parrotfi sh
are often present at the site, but the numbers and occurrence of aggregation and
spawning are very incompletely documented. Observations of spawning were fi rst
brought to the attention of the author by Jim Forrest and Jeanette Denby of the yacht