xiii
Preface
a fundamental change in attitude regarding this life history phenomenon from being
a focus for fi shing to one needful of stewardship and management for long-term
biologically, and hence economically, sustainable use.
Introductory Primer on Aggregating Species
and Their Management
Despite the wide taxonomic diversity of reef fi shes that aggregate to spawn, most
share several core biological attributes. All have a two-phase, or bipartite, life cycle
in which eggs, usually pelagic, hatch into planktonic larvae. This means that while
the juvenile and adult phases are associated with reef ecosystems, the egg and/or
larval phase is planktonic, potentially able to disperse widely and likely a major
determinant of connectivity. However, adult movements between home reefs and
transient aggregation sites can also be considerable and may be another important
aspect of population structure. In this respect, some reef fi shes that aggregate differ
from the ‘sedentary’ form that tends to characterize most reef fi shes and, indeed, is
a basis for the applicability of MPAs to reef ecosystem conservation. Evolutionary
pressures acting in these two phases of the life-cycle are likely to be very different,
and both must be considered when examining hypotheses about where, when and
why aggregations form (Chap. 5 ).
Given the broad taxonomic diversity, ecology and geographic distribution of
aggregating species, it is not surprising that there are substantial differences in many
characteristics of their biology, including longevity, age of sexual maturation, maximum size, diet, spawning mode, etc. This diversity partly accounts for the range of
different aggregation types we observe (Chaps. 2 and 4 ) and is also a primary reason
that some species are intrinsically more vulnerable to overfi shing than others
(Chaps. 8 and 11 ).
Looking at the bigger picture, what we understand relatively little about is the
role of aggregations and aggregating species in the reef ecosystem generally. The
range and number of species, and the large biomasses involved, their mass seasonal
movements and the use of aggregations by egg and adult predators are just some of
the considerations explored in Chap. 2 .
Work is still in the discovery phase for aggregations and regarding the way we
should best be using and managing aggregating species. In many areas, such as the
Pacifi c and Indian Oceans, they are poorly documented and, not surprisingly, little
managed but there is still time to manage and study relatively intact gatherings. In
some parts of the world, on the other hand, such as much of Southeast Asia and
parts of the Caribbean that are very heavily fi shed, aggregations have probably been
lost, with unknown prospects of future recovery. We have only recently begun to
appreciate the overall economic value of species with this habit, how prevalent such
species are in coastal fi sheries, and what would be lost without appropriate management (Chap. 10 ). We have come to realize that not only commercial and recreational
fi sheries need moderation but that even artisanal use can lead to overexploitation of
Preface
a fundamental change in attitude regarding this life history phenomenon from being
a focus for fi shing to one needful of stewardship and management for long-term
biologically, and hence economically, sustainable use.
Introductory Primer on Aggregating Species
and Their Management
Despite the wide taxonomic diversity of reef fi shes that aggregate to spawn, most
share several core biological attributes. All have a two-phase, or bipartite, life cycle
in which eggs, usually pelagic, hatch into planktonic larvae. This means that while
the juvenile and adult phases are associated with reef ecosystems, the egg and/or
larval phase is planktonic, potentially able to disperse widely and likely a major
determinant of connectivity. However, adult movements between home reefs and
transient aggregation sites can also be considerable and may be another important
aspect of population structure. In this respect, some reef fi shes that aggregate differ
from the ‘sedentary’ form that tends to characterize most reef fi shes and, indeed, is
a basis for the applicability of MPAs to reef ecosystem conservation. Evolutionary
pressures acting in these two phases of the life-cycle are likely to be very different,
and both must be considered when examining hypotheses about where, when and
why aggregations form (Chap. 5 ).
Given the broad taxonomic diversity, ecology and geographic distribution of
aggregating species, it is not surprising that there are substantial differences in many
characteristics of their biology, including longevity, age of sexual maturation, maximum size, diet, spawning mode, etc. This diversity partly accounts for the range of
different aggregation types we observe (Chaps. 2 and 4 ) and is also a primary reason
that some species are intrinsically more vulnerable to overfi shing than others
(Chaps. 8 and 11 ).
Looking at the bigger picture, what we understand relatively little about is the
role of aggregations and aggregating species in the reef ecosystem generally. The
range and number of species, and the large biomasses involved, their mass seasonal
movements and the use of aggregations by egg and adult predators are just some of
the considerations explored in Chap. 2 .
Work is still in the discovery phase for aggregations and regarding the way we
should best be using and managing aggregating species. In many areas, such as the
Pacifi c and Indian Oceans, they are poorly documented and, not surprisingly, little
managed but there is still time to manage and study relatively intact gatherings. In
some parts of the world, on the other hand, such as much of Southeast Asia and
parts of the Caribbean that are very heavily fi shed, aggregations have probably been
lost, with unknown prospects of future recovery. We have only recently begun to
appreciate the overall economic value of species with this habit, how prevalent such
species are in coastal fi sheries, and what would be lost without appropriate management (Chap. 10 ). We have come to realize that not only commercial and recreational
fi sheries need moderation but that even artisanal use can lead to overexploitation of