12
M.L. Domeier
aggregation records based on the two types of indicators, direct and indirect, ( www.
SCRFA.org ). This database can be searched and reviewed online, but users should
not cite this database as a sole source of evidence that a species forms a spawning
aggregation because the database lists all reasonably documented records, including
those from fi sher interviews, not just those that have been reliably validated by direct
observations of spawning (Sadovy de Mitcheson et al. 2008 ) . Researchers who use
the SCRFA database will be aided by the fact that SCRFA has separated aggregations
that have been validated via direct means (spawning, hydrated eggs or post-ovulatory
follicles) from those entered solely on the basis of indirect evidence. Those that
appear with only indirect evidence need further verifi cation before they can be cited
as an aggregating species, according to the defi nition above. When using this database it is important to check all the references listed before deciding whether or not
all criteria have been met. A decision to allow incomplete records was made by the
organization to facilitate and stimulate the study and validation of species especially
in cases for which more information is needed.
1.6.1 Observed Aggregations of Reef Fishes; Spawning
Aggregations or Not
An observation of an unusual aggregation of reef fi sh is just the fi rst step to documenting a spawning aggregation. In the absence of long-term behavioural observations and physical sampling of ovaries it is impossible to validate that a particular
aggregation is for the purpose of spawning. For example, during a recent trip to the
Galapagos I observed the king angelfi sh, Holocanthus passer , in an aggregation
(Fig 1.2b ). No spawning occurred despite watching well past sunset. In the absence
of a spawning observation one must collect ovary samples in an attempt to identify
hydrated eggs (can be seen with the naked eye) or post-ovulatory follicles (requires
histology). The presence of well developed ovaries is not an indication of immediate
spawning, since the ovaries can remain in a state of reproductive readiness for long
periods of time (Chap. 9 ). In this example I did not have the permits to collect specimens, but after comparing the H. passer site to other sites, it became obvious that this
was not a spawning aggregation, but rather a result of extreme currents, topography
and food availability. No angelfi sh ( Pomacanthidae) is known to form spawning
aggregations (Appendix). The documentation and validation of spawning aggregations is a diffi cult and time-consuming task, but one that is extremely important.
1.7 The Intriguing Questions That Surround
Spawning Aggregations
Although many papers have been published on spawning aggregations, several vexing
questions remain: (1) why spawn in an aggregation, (2) how do spawning aggregations originally form, (3) from how large a geographic area do adults come to the
M.L. Domeier
aggregation records based on the two types of indicators, direct and indirect, ( www.
SCRFA.org ). This database can be searched and reviewed online, but users should
not cite this database as a sole source of evidence that a species forms a spawning
aggregation because the database lists all reasonably documented records, including
those from fi sher interviews, not just those that have been reliably validated by direct
observations of spawning (Sadovy de Mitcheson et al. 2008 ) . Researchers who use
the SCRFA database will be aided by the fact that SCRFA has separated aggregations
that have been validated via direct means (spawning, hydrated eggs or post-ovulatory
follicles) from those entered solely on the basis of indirect evidence. Those that
appear with only indirect evidence need further verifi cation before they can be cited
as an aggregating species, according to the defi nition above. When using this database it is important to check all the references listed before deciding whether or not
all criteria have been met. A decision to allow incomplete records was made by the
organization to facilitate and stimulate the study and validation of species especially
in cases for which more information is needed.
1.6.1 Observed Aggregations of Reef Fishes; Spawning
Aggregations or Not
An observation of an unusual aggregation of reef fi sh is just the fi rst step to documenting a spawning aggregation. In the absence of long-term behavioural observations and physical sampling of ovaries it is impossible to validate that a particular
aggregation is for the purpose of spawning. For example, during a recent trip to the
Galapagos I observed the king angelfi sh, Holocanthus passer , in an aggregation
(Fig 1.2b ). No spawning occurred despite watching well past sunset. In the absence
of a spawning observation one must collect ovary samples in an attempt to identify
hydrated eggs (can be seen with the naked eye) or post-ovulatory follicles (requires
histology). The presence of well developed ovaries is not an indication of immediate
spawning, since the ovaries can remain in a state of reproductive readiness for long
periods of time (Chap. 9 ). In this example I did not have the permits to collect specimens, but after comparing the H. passer site to other sites, it became obvious that this
was not a spawning aggregation, but rather a result of extreme currents, topography
and food availability. No angelfi sh ( Pomacanthidae) is known to form spawning
aggregations (Appendix). The documentation and validation of spawning aggregations is a diffi cult and time-consuming task, but one that is extremely important.
1.7 The Intriguing Questions That Surround
Spawning Aggregations
Although many papers have been published on spawning aggregations, several vexing
questions remain: (1) why spawn in an aggregation, (2) how do spawning aggregations originally form, (3) from how large a geographic area do adults come to the