217
7 Aggregation Spawning: Biological Aspects of the Early Life History
however for some there is a reasonable chance some larvae might recruit into an
area that constitutes the catchment for migration to their natal aggregation site.
Detailed work on the genetics of aggregation fi shes, particularly those with TAs,
may illustrate the presence of meta-populations in these fi shes.
7.8 Future Work
There is need for more fi eld work documenting spawning output from aggregations,
and the short term transport and entrainment of propagules following through to
recruitment. There are some outstanding examples of projects that are doing an
excellent job of providing at least part of the picture of the importance of aggregations. Work in US Virgin Islands (Beets and Friedlander 1998 ; Nemeth et al. 2007 ,
2008 ) on groupers and snappers has provided a wealth of new information and is
perhaps the best example of how protection of aggregations can allow recovery to
occur. They have not, as yet, expanded the work to include most of ELH and recruitment. The project in the Cayman Islands looking at Nassau grouper (“The Grouper
Moon”) project, a relatively small-scale effort with modest funding, is an outstanding
example of the type of work that needs to be done, as it has attempted to link
aggregation and spawning with the pelagic stage ideally through to benthic recruitment
and is being conducted over a multi-year period (Whaylen et al. 2004, 2007 ) . That
study takes advantage of an existing, protected aggregation to learn what cannot
otherwise be learned, but is applicable elsewhere. Similarly, work on spawning
aggregations in Belize, although effort has been variable year to year, has provided
much information (Heyman et al. 2005 ; Starr et al. 2007 ; Sala et al. 2001 ) but needs
to be continued and make the transition to include studies of the fate of larvae at sea.
Research on snappers in areas like Riley’s Hump in Florida (Burton et al. 2005 )
could be expanded in seasonal duration, geographic scope (to more aggregation locations) and continued on into the pelagic stage. Domeier ( 2004 ) released drift vials at
Riley’s Hump at the projected time of spawning to demonstrate the high probability
of recruits from that aggregation reaching much of South Florida, yet his effort has
not been continued by later researchers documenting aggregation at the site. For so
many species, we know bits and pieces about their aggregation and spawning, but
the whole picture of their ELH remains unclear. These “whole picture” efforts are
needed to include as many locations as possible where aggregations still exist.
Aggregations potentially can be approached from a fi sheries oceanography
standpoint, by targeting studies during the periods when the largest aggregators are
spawning. Methods for doing this are well known from fi sheries work in more temperate latitudes and could be applied with some modifi cations for the tropics. In an
area like Palau, while there is a relatively substantial amount known about aggregations, there has been no work done on ichthyoplankton or fi sheries oceanography.
While large TAs have a mystique that makes them appealing phenomena to
investigate, the smaller and more numerous RA provide many more opportunities
to increase understanding of aggregations. RAs occur regularly in many locations
7 Aggregation Spawning: Biological Aspects of the Early Life History
however for some there is a reasonable chance some larvae might recruit into an
area that constitutes the catchment for migration to their natal aggregation site.
Detailed work on the genetics of aggregation fi shes, particularly those with TAs,
may illustrate the presence of meta-populations in these fi shes.
7.8 Future Work
There is need for more fi eld work documenting spawning output from aggregations,
and the short term transport and entrainment of propagules following through to
recruitment. There are some outstanding examples of projects that are doing an
excellent job of providing at least part of the picture of the importance of aggregations. Work in US Virgin Islands (Beets and Friedlander 1998 ; Nemeth et al. 2007 ,
2008 ) on groupers and snappers has provided a wealth of new information and is
perhaps the best example of how protection of aggregations can allow recovery to
occur. They have not, as yet, expanded the work to include most of ELH and recruitment. The project in the Cayman Islands looking at Nassau grouper (“The Grouper
Moon”) project, a relatively small-scale effort with modest funding, is an outstanding
example of the type of work that needs to be done, as it has attempted to link
aggregation and spawning with the pelagic stage ideally through to benthic recruitment
and is being conducted over a multi-year period (Whaylen et al. 2004, 2007 ) . That
study takes advantage of an existing, protected aggregation to learn what cannot
otherwise be learned, but is applicable elsewhere. Similarly, work on spawning
aggregations in Belize, although effort has been variable year to year, has provided
much information (Heyman et al. 2005 ; Starr et al. 2007 ; Sala et al. 2001 ) but needs
to be continued and make the transition to include studies of the fate of larvae at sea.
Research on snappers in areas like Riley’s Hump in Florida (Burton et al. 2005 )
could be expanded in seasonal duration, geographic scope (to more aggregation locations) and continued on into the pelagic stage. Domeier ( 2004 ) released drift vials at
Riley’s Hump at the projected time of spawning to demonstrate the high probability
of recruits from that aggregation reaching much of South Florida, yet his effort has
not been continued by later researchers documenting aggregation at the site. For so
many species, we know bits and pieces about their aggregation and spawning, but
the whole picture of their ELH remains unclear. These “whole picture” efforts are
needed to include as many locations as possible where aggregations still exist.
Aggregations potentially can be approached from a fi sheries oceanography
standpoint, by targeting studies during the periods when the largest aggregators are
spawning. Methods for doing this are well known from fi sheries work in more temperate latitudes and could be applied with some modifi cations for the tropics. In an
area like Palau, while there is a relatively substantial amount known about aggregations, there has been no work done on ichthyoplankton or fi sheries oceanography.
While large TAs have a mystique that makes them appealing phenomena to
investigate, the smaller and more numerous RA provide many more opportunities
to increase understanding of aggregations. RAs occur regularly in many locations