501
12 Species Case Studies
female was clearly seen and after the lateral break with egg release the female
headed directly down and away from the group. After release of the gametes, the
group descended down quickly and then swam horizontally just above the bottom.
The longnose parrotfi sh generally leaves a highly visible gamete cloud, and at
times there is immediate predation on newly released spawns by black snapper,
Macolor niger . If the parrotfi sh release their gametes close to the bottom, nearly
every spawn is preyed upon by one to several black snappers using the buccal pumping method of ingesting water with eggs (Fig. 12.46 ). This method was fi rst documented by Colin and Bell ( 1991 ) and has been seen in many locations to prey of
eggs of numerous spawning species. The gill rakers of black snappers can fi lter the
eggs from the water. However, not all spawns are preyed upon, particularly if the
longnose parrotfi sh release their gametes high (4–10 m) above the bottom. In such
cases, the black snapper which may be visible in the area, ignore the spawn, perhaps
because they would not be able to reach the area in time to exploit the highly concentrated eggs before dispersal occurs. The egg of the longnose parrotfi sh is spindle-shaped, 1.53–1.60 mm long by 0.54–0.58 mm wide, with relatively blunt ends
(compared to the more acuminate eggs of some species of Scarus ), no oil droplet
and very clear (Colin and Bell 1991 ; PLC unpublished data).
12.16.3 Important Lessons from This Species
It is important to note that despite its common presence on many reefs, and value as
a food fi sh, almost nothing has previously been published on the reproduction of
this species. The group spawning behaviour was unreported. In Palau these observations were made at a dive site called “Blue Corner” which is visited each day by at
least 100 SCUBA divers led by professional dive guides. When the author visited
this site, tourist divers were taking photos of the aggregation and spawning. Despite
this activity, no observer had reported or documented this spawning in any form that
would reach the general knowledge base. Such information could come from a popular article in a dive magazine, natural history magazine, submission of information
to a database (e.g. SCRFA database www.SCRFA.org ), or posting of video or photographs of aggregation and spawning on line (Youtube, other websites).
12.16.4 Comparison with the Indian Ocean Longnose
Parrotfi sh, Hipposcarus harid
Gladstone ( 1996 ) reported Indian Ocean longnoses near Farasan Island, Red Sea
(Saudi Arabia) to aggregate in March or April, with aggregations occurring in only
1 month but differing between years. The fi sh were captured when they swam onto
the reef fl at by groups of men who used monofi lament gill nets. He examined 10
12 Species Case Studies
female was clearly seen and after the lateral break with egg release the female
headed directly down and away from the group. After release of the gametes, the
group descended down quickly and then swam horizontally just above the bottom.
The longnose parrotfi sh generally leaves a highly visible gamete cloud, and at
times there is immediate predation on newly released spawns by black snapper,
Macolor niger . If the parrotfi sh release their gametes close to the bottom, nearly
every spawn is preyed upon by one to several black snappers using the buccal pumping method of ingesting water with eggs (Fig. 12.46 ). This method was fi rst documented by Colin and Bell ( 1991 ) and has been seen in many locations to prey of
eggs of numerous spawning species. The gill rakers of black snappers can fi lter the
eggs from the water. However, not all spawns are preyed upon, particularly if the
longnose parrotfi sh release their gametes high (4–10 m) above the bottom. In such
cases, the black snapper which may be visible in the area, ignore the spawn, perhaps
because they would not be able to reach the area in time to exploit the highly concentrated eggs before dispersal occurs. The egg of the longnose parrotfi sh is spindle-shaped, 1.53–1.60 mm long by 0.54–0.58 mm wide, with relatively blunt ends
(compared to the more acuminate eggs of some species of Scarus ), no oil droplet
and very clear (Colin and Bell 1991 ; PLC unpublished data).
12.16.3 Important Lessons from This Species
It is important to note that despite its common presence on many reefs, and value as
a food fi sh, almost nothing has previously been published on the reproduction of
this species. The group spawning behaviour was unreported. In Palau these observations were made at a dive site called “Blue Corner” which is visited each day by at
least 100 SCUBA divers led by professional dive guides. When the author visited
this site, tourist divers were taking photos of the aggregation and spawning. Despite
this activity, no observer had reported or documented this spawning in any form that
would reach the general knowledge base. Such information could come from a popular article in a dive magazine, natural history magazine, submission of information
to a database (e.g. SCRFA database www.SCRFA.org ), or posting of video or photographs of aggregation and spawning on line (Youtube, other websites).
12.16.4 Comparison with the Indian Ocean Longnose
Parrotfi sh, Hipposcarus harid
Gladstone ( 1996 ) reported Indian Ocean longnoses near Farasan Island, Red Sea
(Saudi Arabia) to aggregate in March or April, with aggregations occurring in only
1 month but differing between years. The fi sh were captured when they swam onto
the reef fl at by groups of men who used monofi lament gill nets. He examined 10