4
M.L. Domeier
available increases catchability and makes aggregations a specifi c target for fi shing;
this calls for specifi c action. I would argue that Claydon’s ( 2004 ) unrestrictive defi -
nition of a spawning aggregation does not adequately differentiate the very unique
act of spawning in large numbers from Simple Migratory Spawning. In fact, the
growing use of the term ‘spawning aggregation’ in management plans and MPA
designations puts greater importance on constructing relatively unambiguous language to describe and defi ne the event. Spawning aggregations are particularly vulnerable to over exploitation simply due to the fact that they constitute particularly
large concentrations of fi sh that are repeatedly predictable in time and space. The
language of the original Domeier and Colin ( 1997 ) defi nition does not directly limit
spawning aggregations to events that repeatedly occur at specifi c times and locations.
Although this criterion was implied when we distinguished between types of
aggregations (see below), I propose the following modifi ed general defi nition for
the sake of clarity:
A Spawning Aggregation is a repeated concentration of conspecifi c marine animals, gathered
for the purpose of spawning, that is predictable in time and space. The density/number of
individuals participating in a spawning aggregation is at least four times that found outside
the aggregation. The spawning aggregation results in a mass point source of offspring.
The term ‘spawning aggregation’ has most widely been applied to coral reef fi sh
examples despite the fact it has never explicitly excluded non reef fi shes or invertebrates; the above modifi ed defi nition substitutes the word ‘animal’ for ‘fi sh’ to
acknowledge that spawning aggregations can occur across a wide spectrum of
marine organisms and habitats. In fact, a recent review of spawning aggregations
included decapods, elasmobranchs and an anadromous catfi sh (Nemeth 2009 ,
Chapter 3). Another subtle change proposed in this defi nition is language relative to
the observed increase in number/density of animals: from “greater than a three-fold
increase” to “at least a four-fold increase.” Domeier and Colin ( 1997 ) recognized
that selecting a density/number criterion was somewhat arbitrary, but the intent was to
be inclusive while excluding non-aggregating mating strategies like streak spawning,
which could involve just three fi sh. This criterion has often been cited in error with
authors omitting the words “greater than;” changing this to “at least four times
greater” will eliminate the confusion.
Claydon ( 2004 ) listed far fewer species 158 species as forming spawning aggregations, while a more recent paper (Sadovy de Mitcheson et al. 2008 ) listed only
67 species (see also Appendix). How can there be such a discrepancy? Sadovy de
Mitcheson et al. ( 2008 ) used the Domeier and Colin ( 1997 ) defi nition of spawning
aggregation while Claydon ( 2004 ) used his new defi nition. However, upon closer
examination of the two papers, the choice of defi nition was not the major factor
that created the large discrepancy; instead, it was Claydon’s use of an unpublished
list of spawning fi shes which fi rst appeared as an appendix to a report from the
Great Barrier Reef Marine Park Authority (GBRMPA) (Russell 2001 ) . The
report appendix lists species purportedly known to form spawning aggregations
along the Great Barrier Reef, but many of the species listed are from an unpublished
list of fi shes cited as “Squire and Samoilys unpublished.” This unpublished list
M.L. Domeier
available increases catchability and makes aggregations a specifi c target for fi shing;
this calls for specifi c action. I would argue that Claydon’s ( 2004 ) unrestrictive defi -
nition of a spawning aggregation does not adequately differentiate the very unique
act of spawning in large numbers from Simple Migratory Spawning. In fact, the
growing use of the term ‘spawning aggregation’ in management plans and MPA
designations puts greater importance on constructing relatively unambiguous language to describe and defi ne the event. Spawning aggregations are particularly vulnerable to over exploitation simply due to the fact that they constitute particularly
large concentrations of fi sh that are repeatedly predictable in time and space. The
language of the original Domeier and Colin ( 1997 ) defi nition does not directly limit
spawning aggregations to events that repeatedly occur at specifi c times and locations.
Although this criterion was implied when we distinguished between types of
aggregations (see below), I propose the following modifi ed general defi nition for
the sake of clarity:
A Spawning Aggregation is a repeated concentration of conspecifi c marine animals, gathered
for the purpose of spawning, that is predictable in time and space. The density/number of
individuals participating in a spawning aggregation is at least four times that found outside
the aggregation. The spawning aggregation results in a mass point source of offspring.
The term ‘spawning aggregation’ has most widely been applied to coral reef fi sh
examples despite the fact it has never explicitly excluded non reef fi shes or invertebrates; the above modifi ed defi nition substitutes the word ‘animal’ for ‘fi sh’ to
acknowledge that spawning aggregations can occur across a wide spectrum of
marine organisms and habitats. In fact, a recent review of spawning aggregations
included decapods, elasmobranchs and an anadromous catfi sh (Nemeth 2009 ,
Chapter 3). Another subtle change proposed in this defi nition is language relative to
the observed increase in number/density of animals: from “greater than a three-fold
increase” to “at least a four-fold increase.” Domeier and Colin ( 1997 ) recognized
that selecting a density/number criterion was somewhat arbitrary, but the intent was to
be inclusive while excluding non-aggregating mating strategies like streak spawning,
which could involve just three fi sh. This criterion has often been cited in error with
authors omitting the words “greater than;” changing this to “at least four times
greater” will eliminate the confusion.
Claydon ( 2004 ) listed far fewer species 158 species as forming spawning aggregations, while a more recent paper (Sadovy de Mitcheson et al. 2008 ) listed only
67 species (see also Appendix). How can there be such a discrepancy? Sadovy de
Mitcheson et al. ( 2008 ) used the Domeier and Colin ( 1997 ) defi nition of spawning
aggregation while Claydon ( 2004 ) used his new defi nition. However, upon closer
examination of the two papers, the choice of defi nition was not the major factor
that created the large discrepancy; instead, it was Claydon’s use of an unpublished
list of spawning fi shes which fi rst appeared as an appendix to a report from the
Great Barrier Reef Marine Park Authority (GBRMPA) (Russell 2001 ) . The
report appendix lists species purportedly known to form spawning aggregations
along the Great Barrier Reef, but many of the species listed are from an unpublished
list of fi shes cited as “Squire and Samoilys unpublished.” This unpublished list