118
P.L. Colin
5.1 Introduction
Our understanding of why spawning aggregations of tropical and temperate marine
fi shes occur at particular places (“where”) and times (“when”) is only in its preliminary stages. Spawning aggregations were fi rst noted by fi shers, probably discovering
them initially by chance. By returning later to the same locations, particularly at the
same daily time, lunar phase or season, they gradually learned that aggregations
occur on a lunar or annual schedule and used this knowledge to increase their ability
to capture food. Such knowledge is typical of human populations dependent on
direct exploitation of the natural world for survival. The scope and limits of the
locations and timing for the species involved would become what we know today as
traditional ecological knowledge (TEK, also known as local ecological knowledge
see Chap. 10 ).
Nearly all reef fi shes have a pelagic larval life history stage, usually starting
either with the hatching of demersal eggs into free-swimming larvae or (in the case
of most aggregators) the release and fertilization of planktonic eggs. For both aggregating and non-aggregating species, spawning is often concentrated into a relatively
narrow time frame. High mortality during the pelagic phase is normal with few
“propagules” surviving to settlement. The time and location of spawning aggregations
are intimately involved with the behaviour and ecology of the spawning adults and the
pelagic life history of larvae through oceanographic and climatic interactions.
Questions immediately arise for scientists regarding “why this site” and “why
this time” are utilized by a particular species and, if multiple species use the same
site simultaneously or sequentially, “is this site special for some reason”? Despite
recent attention, scientists are still wondering about the ultimate “why” of location
and timing. The science of reef fi sh spawning aggregations is still largely in the
basic “discovery” phase with the information available coming from a limited
geographic scope and suite of species, often restricted to fi sher interviews regarding
TEK. Few researchers conduct fi eld work on the science of aggregations and it is
understandable that a clear view of spawning aggregations has yet to emerge.
Increased attention from the conservation advocacy community has resulted in
redirection of support to conservation efforts in which detailed scientifi c study of
aggregations is generally regarded as unnecessary for specifi c conservation agendas.
For example, the promotion of Marine Protected Areas (MPAs), which may or may
not include aggregation areas, tends to discourage new research with the rationale
that once designated such areas are thereby protected, hence there is little need to
monitor or understand aggregations. It also sidesteps other possible management
approaches, such as seasonal and market closures. Efforts to obtain “hard” knowledge on spawning aggregations often become subservient to political or social
considerations.
With around 100 species of tropical and temperate reef fi shes found in all
oceans presently reported to aggregate for spawning (Chaps. 4 and 8 , Appendix ,
Sadovy de Mitcheson et al. 2008 ) , and perhaps many more species doing so without
our knowledge, there is potentially a high diversity of reproductive strategies.
P.L. Colin
5.1 Introduction
Our understanding of why spawning aggregations of tropical and temperate marine
fi shes occur at particular places (“where”) and times (“when”) is only in its preliminary stages. Spawning aggregations were fi rst noted by fi shers, probably discovering
them initially by chance. By returning later to the same locations, particularly at the
same daily time, lunar phase or season, they gradually learned that aggregations
occur on a lunar or annual schedule and used this knowledge to increase their ability
to capture food. Such knowledge is typical of human populations dependent on
direct exploitation of the natural world for survival. The scope and limits of the
locations and timing for the species involved would become what we know today as
traditional ecological knowledge (TEK, also known as local ecological knowledge
see Chap. 10 ).
Nearly all reef fi shes have a pelagic larval life history stage, usually starting
either with the hatching of demersal eggs into free-swimming larvae or (in the case
of most aggregators) the release and fertilization of planktonic eggs. For both aggregating and non-aggregating species, spawning is often concentrated into a relatively
narrow time frame. High mortality during the pelagic phase is normal with few
“propagules” surviving to settlement. The time and location of spawning aggregations
are intimately involved with the behaviour and ecology of the spawning adults and the
pelagic life history of larvae through oceanographic and climatic interactions.
Questions immediately arise for scientists regarding “why this site” and “why
this time” are utilized by a particular species and, if multiple species use the same
site simultaneously or sequentially, “is this site special for some reason”? Despite
recent attention, scientists are still wondering about the ultimate “why” of location
and timing. The science of reef fi sh spawning aggregations is still largely in the
basic “discovery” phase with the information available coming from a limited
geographic scope and suite of species, often restricted to fi sher interviews regarding
TEK. Few researchers conduct fi eld work on the science of aggregations and it is
understandable that a clear view of spawning aggregations has yet to emerge.
Increased attention from the conservation advocacy community has resulted in
redirection of support to conservation efforts in which detailed scientifi c study of
aggregations is generally regarded as unnecessary for specifi c conservation agendas.
For example, the promotion of Marine Protected Areas (MPAs), which may or may
not include aggregation areas, tends to discourage new research with the rationale
that once designated such areas are thereby protected, hence there is little need to
monitor or understand aggregations. It also sidesteps other possible management
approaches, such as seasonal and market closures. Efforts to obtain “hard” knowledge on spawning aggregations often become subservient to political or social
considerations.
With around 100 species of tropical and temperate reef fi shes found in all
oceans presently reported to aggregate for spawning (Chaps. 4 and 8 , Appendix ,
Sadovy de Mitcheson et al. 2008 ) , and perhaps many more species doing so without
our knowledge, there is potentially a high diversity of reproductive strategies.