7
1 Revisiting Spawning Aggregations: Defi nitions and Challenges
1.3 Types of Spawning Aggregations
Domeier and Colin ( 1997 ) subdivided spawning aggregations into two distinct
types, Resident and Transient , based upon (1) the frequency with which the spawning aggregation occurs, (2) the length of time the aggregation persists, (3) the site
specifi city of the aggregation, and (4) the distance that individual fi sh travel to the
aggregation site. The original defi nitions are as follows:
Resident spawning aggregations draw individuals from a relatively small and
local area. The spawning site can be reached through a migration of a few hours or
less and often lies within the home range of the participating individuals. They usually (1) occur at a specifi c time of day over numerous days, (2) last only a few hours
or less, (3) occur daily over an often lengthy reproductive period of the year, and (4)
can occur year round. A single day of spawning for an individual participating in a
resident spawning aggregation represents a small fraction of that individual’s annual
reproductive effort.
Transient spawning aggregations draw individuals from a relatively large area.
Individuals must travel days or weeks to reach the aggregation site. Transient spawning aggregations often (1) occur during a very specifi c portion of 1 or 2 months of
the year; (2) persist for a period of days or at most a few weeks and (3) do not occur
year round. A single transient spawning aggregation may represent the total reproductive effort for participating individuals.
Claydon ( 2004 ) suggested that the differentiation between resident and transient
spawning aggregations is artifi cial, with the distinction being a simple matter of
scale. He argued that all spawning aggregations are resident because the aggregation
site lies within the catchment area of participating individuals, and that all aggregations are transient because they are temporary. The term ‘catchment area’ has been
increasingly used relative to spawning aggregations in reference to the total geographic region from which individuals are drawn for a specifi c spawning aggregation. Catchment areas are relative to the species or population that aggregates at
an individual site, rather than a property of an individual animal as indicated by
Claydon. Therefore, a single site may have more than one catchment area if it is a
multi-species site, and a single species may have overlapping catchment areas if it
uses multiple sites in a small area. Domeier and Colin ( 1997 ) stated that Resident
spawning aggregations are drawn from a “relatively small and local area” while
Transient aggregations “draw individuals from a relatively large area;” this language
is ambiguous. Although Domeier and Colin use the term “home range” in defi ning
Transient spawning aggregation, Nemeth ( 2009 ) clarifi ed the distinction between
Resident and Transient spawning aggregations by adding the term ‘home range’ to
both defi nitions, such that individuals migrate “within or nearby” their home range
for Resident aggregations and “well outside” their home range for Transient spawning aggregations. Accepting Nemeth’s distinction I have modifi ed the original defi -
nitions as follows-modifi cations are bolded:
Resident spawning aggregations draw individuals to a site within or nearby their
adult home range. They usually (1) occur at a specifi c time of day over numerous
1 Revisiting Spawning Aggregations: Defi nitions and Challenges
1.3 Types of Spawning Aggregations
Domeier and Colin ( 1997 ) subdivided spawning aggregations into two distinct
types, Resident and Transient , based upon (1) the frequency with which the spawning aggregation occurs, (2) the length of time the aggregation persists, (3) the site
specifi city of the aggregation, and (4) the distance that individual fi sh travel to the
aggregation site. The original defi nitions are as follows:
Resident spawning aggregations draw individuals from a relatively small and
local area. The spawning site can be reached through a migration of a few hours or
less and often lies within the home range of the participating individuals. They usually (1) occur at a specifi c time of day over numerous days, (2) last only a few hours
or less, (3) occur daily over an often lengthy reproductive period of the year, and (4)
can occur year round. A single day of spawning for an individual participating in a
resident spawning aggregation represents a small fraction of that individual’s annual
reproductive effort.
Transient spawning aggregations draw individuals from a relatively large area.
Individuals must travel days or weeks to reach the aggregation site. Transient spawning aggregations often (1) occur during a very specifi c portion of 1 or 2 months of
the year; (2) persist for a period of days or at most a few weeks and (3) do not occur
year round. A single transient spawning aggregation may represent the total reproductive effort for participating individuals.
Claydon ( 2004 ) suggested that the differentiation between resident and transient
spawning aggregations is artifi cial, with the distinction being a simple matter of
scale. He argued that all spawning aggregations are resident because the aggregation
site lies within the catchment area of participating individuals, and that all aggregations are transient because they are temporary. The term ‘catchment area’ has been
increasingly used relative to spawning aggregations in reference to the total geographic region from which individuals are drawn for a specifi c spawning aggregation. Catchment areas are relative to the species or population that aggregates at
an individual site, rather than a property of an individual animal as indicated by
Claydon. Therefore, a single site may have more than one catchment area if it is a
multi-species site, and a single species may have overlapping catchment areas if it
uses multiple sites in a small area. Domeier and Colin ( 1997 ) stated that Resident
spawning aggregations are drawn from a “relatively small and local area” while
Transient aggregations “draw individuals from a relatively large area;” this language
is ambiguous. Although Domeier and Colin use the term “home range” in defi ning
Transient spawning aggregation, Nemeth ( 2009 ) clarifi ed the distinction between
Resident and Transient spawning aggregations by adding the term ‘home range’ to
both defi nitions, such that individuals migrate “within or nearby” their home range
for Resident aggregations and “well outside” their home range for Transient spawning aggregations. Accepting Nemeth’s distinction I have modifi ed the original defi -
nitions as follows-modifi cations are bolded:
Resident spawning aggregations draw individuals to a site within or nearby their
adult home range. They usually (1) occur at a specifi c time of day over numerous