2
M.L. Domeier
1.1 Introduction
Animals are known to gather en masse for shelter or physiological benefi ts
(i.e. conservation of heat or water), to avoid predators, to migrate, to feed, and to
reproduce. One such reproductive aggregation known to occur in marine reef fi shes,
as well as other fi shes and invertebrates, is the spawning aggregation. Although the
term spawning aggregation has been used in the literature for decades, it was not
formerly defi ned until 1997 (Domeier and Colin 1997 ) . While the 1997 paper
reviewed just 82 publications spanning 73 years, in contrast the Domeier and Colin
( 1997 ) review has been cited over 200 times in just 14 years, indicating a recent and
dramatic focus on spawning aggregations.
Spawning aggregations are predictable in time and space and therefore often the
target of intense directed fi sheries. Much of the recent focus on spawning aggregations can be attributed to the deleterious effect that fi shing them can have on the
target species (Sala et al. 2001 ; Sadovy and Domeier 2005 ) . The challenge of regulating reef fi sheries has brought the science of spawning aggregations to the forefront of management discussions, often in relation to the designation of marine
protected areas (MPA) in tropical regions. The large increase in published spawning
aggregation related data, and a proposed alternative defi nition of the phenomenon
( Claydon 2004 ), warrants a re-examination of the general defi nition of a spawning
aggregation, as well as considering the different types of aggregations. In addition,
there is a need for establishing very clear criteria to properly document a spawning
aggregation, particularly when a new example is being added to the worldwide list
of species known to form them (Appendix ). The study of the spawning biology and
behaviour of fi shes should be encouraged, but discipline and restraint are necessary before labelling a new spawning aggregation. Defi nitions are not intended to
constrain discussion, instead they are meant to streamline communication, and in
the current case, implicate special fi sheries circumstances in relation to management and conservation considerations.
1.2 General Spawning Aggregation Defi nitions
Domeier and Colin ( 1997 ) defi ned a spawning aggregation “as a group of conspecifi c
fi sh gathered for the purpose of spawning, with fi sh densities or numbers signifi -
cantly higher than those found in the area of aggregation during the non-reproductive
periods (Fig. 1.1 ). For fi shes, such as jacks (Carangidae), mullet (Mugilidae),
rabbitfi shes (Siganidae) and surgeonfi shes (Acanthuridae) which normally occur
in dense schools, when in a spawning aggregation they must occur in signifi cantly
greater number and take up signifi cantly more space than non-reproductive fi sh.”
The authors discuss the need for a more quantitative defi nition but acknowledge a
lack of data to do so. They suggest requiring a greater than three-fold increase in
fi sh density to exclude streak spawning events (a single spawning pair joined by a
solitary male during the spawning rush).
M.L. Domeier
1.1 Introduction
Animals are known to gather en masse for shelter or physiological benefi ts
(i.e. conservation of heat or water), to avoid predators, to migrate, to feed, and to
reproduce. One such reproductive aggregation known to occur in marine reef fi shes,
as well as other fi shes and invertebrates, is the spawning aggregation. Although the
term spawning aggregation has been used in the literature for decades, it was not
formerly defi ned until 1997 (Domeier and Colin 1997 ) . While the 1997 paper
reviewed just 82 publications spanning 73 years, in contrast the Domeier and Colin
( 1997 ) review has been cited over 200 times in just 14 years, indicating a recent and
dramatic focus on spawning aggregations.
Spawning aggregations are predictable in time and space and therefore often the
target of intense directed fi sheries. Much of the recent focus on spawning aggregations can be attributed to the deleterious effect that fi shing them can have on the
target species (Sala et al. 2001 ; Sadovy and Domeier 2005 ) . The challenge of regulating reef fi sheries has brought the science of spawning aggregations to the forefront of management discussions, often in relation to the designation of marine
protected areas (MPA) in tropical regions. The large increase in published spawning
aggregation related data, and a proposed alternative defi nition of the phenomenon
( Claydon 2004 ), warrants a re-examination of the general defi nition of a spawning
aggregation, as well as considering the different types of aggregations. In addition,
there is a need for establishing very clear criteria to properly document a spawning
aggregation, particularly when a new example is being added to the worldwide list
of species known to form them (Appendix ). The study of the spawning biology and
behaviour of fi shes should be encouraged, but discipline and restraint are necessary before labelling a new spawning aggregation. Defi nitions are not intended to
constrain discussion, instead they are meant to streamline communication, and in
the current case, implicate special fi sheries circumstances in relation to management and conservation considerations.
1.2 General Spawning Aggregation Defi nitions
Domeier and Colin ( 1997 ) defi ned a spawning aggregation “as a group of conspecifi c
fi sh gathered for the purpose of spawning, with fi sh densities or numbers signifi -
cantly higher than those found in the area of aggregation during the non-reproductive
periods (Fig. 1.1 ). For fi shes, such as jacks (Carangidae), mullet (Mugilidae),
rabbitfi shes (Siganidae) and surgeonfi shes (Acanthuridae) which normally occur
in dense schools, when in a spawning aggregation they must occur in signifi cantly
greater number and take up signifi cantly more space than non-reproductive fi sh.”
The authors discuss the need for a more quantitative defi nition but acknowledge a
lack of data to do so. They suggest requiring a greater than three-fold increase in
fi sh density to exclude streak spawning events (a single spawning pair joined by a
solitary male during the spawning rush).