99
4 Spawning Aggregations in Reef Fishes; Ecological and Evolutionary Processes
passes (Gladstone 1986 ; Hamilton 2004 , Chaps. 9 , 12.13 and 12.15 ) and involves
pair spawning (Colin 2010a ) . In the case of humphead wrasse, the increases in local
density are a reproductive phenomenon and represent migrations of ~5 km to the
spawning site Colin ( 2010a ) . However for bumphead parrotfi sh there is no evidence
to date that schools are augmented by migrants during reproduction. In summary,
spawning behaviour was predicted by size, abundance and nutritional ecology with
transient spawners represented by large carnivores and resident spawners by intermediate sized species, usually benthic grazers. Large wrasses are an exception and
prompted an additional analysis to determine whether spawning behaviour might be
better explained by demographic and life-history variables.
4.4.2 The Infl uence of Morphology, Demography
and Life History on the Classifi cation of Resident
and Transient Spawning Modes
The analysis described in this section focused on the four families of reef fi sh,
surgeonfi sh and wrasses (resident) and snapper and grouper (transient) fi shes which
make up 78% of the verifi ed aggregate spawners. Surgeonfi shes and parrotfi shes
show a high degree of similarity in terms of habitat, foraging behaviour, size and
abundance profi les (Choat and Bellwood 1985 ; Choat et al. 2002, 2004 ) . Snappers
and groupers are more diverse ecologically but also share properties of size and
trophic biology. Although the families within each spawning group share properties
of size and trophic biology they differ signifi cantly in life history features. Between
surgeonfi shes and parrotfi shes (resident) there are differences in growth patterns
and maximum ages in each group. Small surgeonfi shes <20 cm FL may achieve
maximum ages of 45 years. Larger species frequently achieve ages in excess of
40 years (Choat and Axe 1996 ; Choat and Robertson 2002 ) . Most tropical labrids
(especially parrotfi shes) have shorter life spans including very large species. For
example the humphead wrasse achieves maximum sizes an order of magnitude
greater than most acanthurids but frequently reach only half the life-span of this
group (Choat and Robertson 2002 ; Choat et al. 2006 ) . They also display different
growth curves, indeterminate in wrasses, and highly asymptotic in surgeonfi shes
(Choat and Robertson 2002 ) .
A similar set of contrasts is seen in groupers and snappers (transient). Species of
Plectropomus (the squaretail coralgrouper, the leopard coralgrouper, P. leopardus,
and blacksaddle coralgrouper P. laevis) reach lengths in excess of 70 cm but maximum
ages of usually 12–15 years with a maximum of 18 (Ferreira and Russ 1994 ;
Williams et al. 2008 ; Heupel et al. 2010 ) . Relatively small snappers, such as fi velined snapper, L. quinquelineatus , with a maximum size of <25 cm, achieve ages in
excess of 30 years (Newman et al. 1996 ) while large species may exceed 50 years
(Marriott et al. 2007 ) . Each of the transient spawning groups also display the same
differentiation of growth curves; groupers tend to have indeterminate growth curves
while snappers usually display the same highly asymptotic growth curves as seen in
4 Spawning Aggregations in Reef Fishes; Ecological and Evolutionary Processes
passes (Gladstone 1986 ; Hamilton 2004 , Chaps. 9 , 12.13 and 12.15 ) and involves
pair spawning (Colin 2010a ) . In the case of humphead wrasse, the increases in local
density are a reproductive phenomenon and represent migrations of ~5 km to the
spawning site Colin ( 2010a ) . However for bumphead parrotfi sh there is no evidence
to date that schools are augmented by migrants during reproduction. In summary,
spawning behaviour was predicted by size, abundance and nutritional ecology with
transient spawners represented by large carnivores and resident spawners by intermediate sized species, usually benthic grazers. Large wrasses are an exception and
prompted an additional analysis to determine whether spawning behaviour might be
better explained by demographic and life-history variables.
4.4.2 The Infl uence of Morphology, Demography
and Life History on the Classifi cation of Resident
and Transient Spawning Modes
The analysis described in this section focused on the four families of reef fi sh,
surgeonfi sh and wrasses (resident) and snapper and grouper (transient) fi shes which
make up 78% of the verifi ed aggregate spawners. Surgeonfi shes and parrotfi shes
show a high degree of similarity in terms of habitat, foraging behaviour, size and
abundance profi les (Choat and Bellwood 1985 ; Choat et al. 2002, 2004 ) . Snappers
and groupers are more diverse ecologically but also share properties of size and
trophic biology. Although the families within each spawning group share properties
of size and trophic biology they differ signifi cantly in life history features. Between
surgeonfi shes and parrotfi shes (resident) there are differences in growth patterns
and maximum ages in each group. Small surgeonfi shes <20 cm FL may achieve
maximum ages of 45 years. Larger species frequently achieve ages in excess of
40 years (Choat and Axe 1996 ; Choat and Robertson 2002 ) . Most tropical labrids
(especially parrotfi shes) have shorter life spans including very large species. For
example the humphead wrasse achieves maximum sizes an order of magnitude
greater than most acanthurids but frequently reach only half the life-span of this
group (Choat and Robertson 2002 ; Choat et al. 2006 ) . They also display different
growth curves, indeterminate in wrasses, and highly asymptotic in surgeonfi shes
(Choat and Robertson 2002 ) .
A similar set of contrasts is seen in groupers and snappers (transient). Species of
Plectropomus (the squaretail coralgrouper, the leopard coralgrouper, P. leopardus,
and blacksaddle coralgrouper P. laevis) reach lengths in excess of 70 cm but maximum
ages of usually 12–15 years with a maximum of 18 (Ferreira and Russ 1994 ;
Williams et al. 2008 ; Heupel et al. 2010 ) . Relatively small snappers, such as fi velined snapper, L. quinquelineatus , with a maximum size of <25 cm, achieve ages in
excess of 30 years (Newman et al. 1996 ) while large species may exceed 50 years
(Marriott et al. 2007 ) . Each of the transient spawning groups also display the same
differentiation of growth curves; groupers tend to have indeterminate growth curves
while snappers usually display the same highly asymptotic growth curves as seen in