464
12 Species Case Studies
(Johannes 1978, 1981 ) have now been verifi ed as such. Transient aggregations are
confi rmed for the twin-spot snapper, Lutjanus bohar (known as “red bass” in
Australia), discussed subsequently, and the blue-lined sea bream, Symphorichthys
spilurus (Chap. 12.11 ). Suzuki and Hioki ( 1979 ) reported group-spawning by 10 or
more captive common blue-stripe snapper Lutjanus kasmira in an aquarium during
evening hours. Sala et al. ( 2003 ) described spawning in species from the eastern
Pacifi c (e.g. Lutjanus argentiventris and L. novemfasciatus ) and some may have
true spawning aggregations. All lutjanid species that have been observed to spawn
to date do so in large sub-groups that break out of the main aggregation i.e. groupspawning. Dog snapper Lutjanus jocu also spawns in aggregations (see Fig. 9.11).
Some of the larger snappers appear to be quite long-lived, making them potentially
easy to overfi sh. If they are also fi shed on their spawning aggregations, then they are
likely to need management to ensure that the fi shery continues in the long term.
12.10.4.1 Twin-Spot Snapper – Lutjanus bohar
The twin-spot snapper occurs in the Indo-Pacifi c from east Africa to the Marquesas
and Line Islands, north to the Ryukyu Islands, and south to Australia. It mainly
lives around oceanic islands and is found in groups of up to thousands of fi sh
(Fig. 12.24 ). It is an important commercial fi sh, as well as a popular game fi sh,
taken by a wide range of fi shing gears. There is little fi shery information on the
twin-spot snapper but it is known to be fi shed on its aggregations in some locations
and has shown declines in some fi sheries. Typically marketed dead, the species is
also found in the Hong Kong-based live reef food fi sh trade, it is avoided in some
areas because it can be ciguatoxic (Gillespie et al. 1986 ; Wright et al. 1986 ; R
Hamilton, personal communication 2003 ; Sadovy et al. 2003a ; Marriott and
Mapstone 2006 ; Sadovy 2007 ) .
The species is large and long-lived, attaining 56 years of age and up to 90 cm
total length (TL). The species is probably gonochoristic (Allen and Talbot 1985 ;
www.fi shbase.org ; Marriott and Mapstone 2006 ; Mariott et al. 2007 ) with females
maturing at about 43 cm fork length (FL) (about 9 years).
In Palau, the species has long been reported to form aggregations (Johannes
1981 ; Sadovy 2007 ) and spawning was recently recorded from Palau just after
dawn (Fig. 12.24 ). These aggregations are massive and, as a spectacle of nature,
rival those of the cubera snapper found in Belize (Heyman et al. 2005 ) . As with
some other species of fi shes spawning in Palau, the released eggs and sperm are
often targeted by black snapper, Macolor niger , only seconds after release. They
are reported to form probable spawning aggregations and may spawn every month
in Papua New Guinea and the Solomon Islands during full moon and the third lunar
quarter in groups of several hundreds of fi sh (R Hamilton, personal communication 2003 ) . Fish in Palau are known to aggregate and spawn at the southern end
of Peleliu Island, the southernmost extension of the shallow reef around the
main Palau group. The aggregations are closely associated with those of the
12 Species Case Studies
(Johannes 1978, 1981 ) have now been verifi ed as such. Transient aggregations are
confi rmed for the twin-spot snapper, Lutjanus bohar (known as “red bass” in
Australia), discussed subsequently, and the blue-lined sea bream, Symphorichthys
spilurus (Chap. 12.11 ). Suzuki and Hioki ( 1979 ) reported group-spawning by 10 or
more captive common blue-stripe snapper Lutjanus kasmira in an aquarium during
evening hours. Sala et al. ( 2003 ) described spawning in species from the eastern
Pacifi c (e.g. Lutjanus argentiventris and L. novemfasciatus ) and some may have
true spawning aggregations. All lutjanid species that have been observed to spawn
to date do so in large sub-groups that break out of the main aggregation i.e. groupspawning. Dog snapper Lutjanus jocu also spawns in aggregations (see Fig. 9.11).
Some of the larger snappers appear to be quite long-lived, making them potentially
easy to overfi sh. If they are also fi shed on their spawning aggregations, then they are
likely to need management to ensure that the fi shery continues in the long term.
12.10.4.1 Twin-Spot Snapper – Lutjanus bohar
The twin-spot snapper occurs in the Indo-Pacifi c from east Africa to the Marquesas
and Line Islands, north to the Ryukyu Islands, and south to Australia. It mainly
lives around oceanic islands and is found in groups of up to thousands of fi sh
(Fig. 12.24 ). It is an important commercial fi sh, as well as a popular game fi sh,
taken by a wide range of fi shing gears. There is little fi shery information on the
twin-spot snapper but it is known to be fi shed on its aggregations in some locations
and has shown declines in some fi sheries. Typically marketed dead, the species is
also found in the Hong Kong-based live reef food fi sh trade, it is avoided in some
areas because it can be ciguatoxic (Gillespie et al. 1986 ; Wright et al. 1986 ; R
Hamilton, personal communication 2003 ; Sadovy et al. 2003a ; Marriott and
Mapstone 2006 ; Sadovy 2007 ) .
The species is large and long-lived, attaining 56 years of age and up to 90 cm
total length (TL). The species is probably gonochoristic (Allen and Talbot 1985 ;
www.fi shbase.org ; Marriott and Mapstone 2006 ; Mariott et al. 2007 ) with females
maturing at about 43 cm fork length (FL) (about 9 years).
In Palau, the species has long been reported to form aggregations (Johannes
1981 ; Sadovy 2007 ) and spawning was recently recorded from Palau just after
dawn (Fig. 12.24 ). These aggregations are massive and, as a spectacle of nature,
rival those of the cubera snapper found in Belize (Heyman et al. 2005 ) . As with
some other species of fi shes spawning in Palau, the released eggs and sperm are
often targeted by black snapper, Macolor niger , only seconds after release. They
are reported to form probable spawning aggregations and may spawn every month
in Papua New Guinea and the Solomon Islands during full moon and the third lunar
quarter in groups of several hundreds of fi sh (R Hamilton, personal communication 2003 ) . Fish in Palau are known to aggregate and spawn at the southern end
of Peleliu Island, the southernmost extension of the shallow reef around the
main Palau group. The aggregations are closely associated with those of the