578
Y. Sadovy de Mitcheson and P.L. Colin
for the year as determined by a clear and consistent counting protocol. The reality is
that the Nassau grouper is exceptionally diffi cult to survey because the aggregation
changes from a two-dimensional to a three-dimensional form according to time of
day and fi sh numbers. Therefore, estimating numbers is a challenge akin to counting
birds in large moving fl ocks and needs very careful planning.
Overall, there is a surprising lack of new information being generated for those
species already known to aggregate, new localities of aggregations or of additional
species suspected to have spawning aggregations (see sections B and C in Appendix ).
Aggregations reported in fi sher interviews should be validated to confi rm timing,
species and locations. Nonetheless, the locations of aggregations of commercially
important species, unless already widely known, should generally be treated as
privileged data for use by managers and other concerned parties; this respects the
users of the site and avoids the possibility of revealing the location that could result
in additional fi shing pressure. Detailed information on aggregations assists in management and conservation planning and enables enforcement to be fi nely tuned to
the times of peak numbers, saving on manpower and other costs.
While observational work, such as underwater surveys, is important, there is also
a need for specimen and fi shery-based research to determine catch rates, sexual
state, fi sh sizes, and fi sher perspectives, etc. Much can be achieved based on very
simple and inexpensive methodologies and will be very useful if samples are
representative and large enough to have scientifi c validity. Moreover, much can be
done non-destructively, a major concern for protected or threatened species. As
one example, while sagittal otoliths are typically used to age tropical fi shes, work
on the threatened goliath grouper has shown that clipped dorsal fi ns can be used for
ageing, obviating the need to kill fi sh. For reproductive work on spawning seasonality
and timing, simple GSI methods can be applied (Chap. 9 ), while live fi sh can be
cannulated for more precise information on timing of reproduction in any one lunar
cycle. Simple training can enable workers to obtain scientifi cally robust information
easily and inexpensively from individual fi sh obtained from fi shers or markets.
In areas where fi sheries are based on aggregations or on fi shes migrating to
aggregation sites, efforts should be made to work with fi shers to gather data. Positive
interactions with fi shers, including buying specimens from them at premium prices
often at the fi shing site or paying to gather data (measure fi sh, determine sex, weigh
gonads), take gonads for histology, etc. can allow for messages of conservation and
information on species to be exchanged. Often seeing that the fi sh they are catching
are the egg-bearing females, or discussion of decreasing fi sh sizes and numbers
of catches over time, may have an eye-opening effect on fi shers, which can be
amplifi ed by the simple presence of scientists trying to ascertain how to maintain fi sh
populations for the eventual benefi t of the fi shery. This is particularly true if older
individuals who might be concerned about what they are leaving behind and who
have seen big changes in their lifetimes are involved. These fi shers can be a particularly important source of understanding and inspiration for younger fi shers with less
experience.
Given how little is understood of aggregating species, hopes should not be pinned
on radical or alternative solutions to overfi shing, such as restocking or mariculture
Y. Sadovy de Mitcheson and P.L. Colin
for the year as determined by a clear and consistent counting protocol. The reality is
that the Nassau grouper is exceptionally diffi cult to survey because the aggregation
changes from a two-dimensional to a three-dimensional form according to time of
day and fi sh numbers. Therefore, estimating numbers is a challenge akin to counting
birds in large moving fl ocks and needs very careful planning.
Overall, there is a surprising lack of new information being generated for those
species already known to aggregate, new localities of aggregations or of additional
species suspected to have spawning aggregations (see sections B and C in Appendix ).
Aggregations reported in fi sher interviews should be validated to confi rm timing,
species and locations. Nonetheless, the locations of aggregations of commercially
important species, unless already widely known, should generally be treated as
privileged data for use by managers and other concerned parties; this respects the
users of the site and avoids the possibility of revealing the location that could result
in additional fi shing pressure. Detailed information on aggregations assists in management and conservation planning and enables enforcement to be fi nely tuned to
the times of peak numbers, saving on manpower and other costs.
While observational work, such as underwater surveys, is important, there is also
a need for specimen and fi shery-based research to determine catch rates, sexual
state, fi sh sizes, and fi sher perspectives, etc. Much can be achieved based on very
simple and inexpensive methodologies and will be very useful if samples are
representative and large enough to have scientifi c validity. Moreover, much can be
done non-destructively, a major concern for protected or threatened species. As
one example, while sagittal otoliths are typically used to age tropical fi shes, work
on the threatened goliath grouper has shown that clipped dorsal fi ns can be used for
ageing, obviating the need to kill fi sh. For reproductive work on spawning seasonality
and timing, simple GSI methods can be applied (Chap. 9 ), while live fi sh can be
cannulated for more precise information on timing of reproduction in any one lunar
cycle. Simple training can enable workers to obtain scientifi cally robust information
easily and inexpensively from individual fi sh obtained from fi shers or markets.
In areas where fi sheries are based on aggregations or on fi shes migrating to
aggregation sites, efforts should be made to work with fi shers to gather data. Positive
interactions with fi shers, including buying specimens from them at premium prices
often at the fi shing site or paying to gather data (measure fi sh, determine sex, weigh
gonads), take gonads for histology, etc. can allow for messages of conservation and
information on species to be exchanged. Often seeing that the fi sh they are catching
are the egg-bearing females, or discussion of decreasing fi sh sizes and numbers
of catches over time, may have an eye-opening effect on fi shers, which can be
amplifi ed by the simple presence of scientists trying to ascertain how to maintain fi sh
populations for the eventual benefi t of the fi shery. This is particularly true if older
individuals who might be concerned about what they are leaving behind and who
have seen big changes in their lifetimes are involved. These fi shers can be a particularly important source of understanding and inspiration for younger fi shers with less
experience.
Given how little is understood of aggregating species, hopes should not be pinned
on radical or alternative solutions to overfi shing, such as restocking or mariculture