271
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
small numbers of fi sh concentrated briefl y in one small area can appear remarkable, even scientifi c workers newly exposed to aggregations may have little idea
about former abundances. As one specifi c example in reef fi sheries, young
researchers today in the Caribbean conducting UVC are often impressed to see a
few hundred Nassau grouper gathered in one aggregation at sites that just three
or four decades ago held tens of thousands of fi sh (YSM personal observation).
Old fi lm footage and verbal accounts of divers, biologists, or fi shermen who have
seen such spectacular biological events are particularly valuable for highlighting
such changes.
8.7 Data Gaps
Based on the above review, we identify key data gaps which, if addressed, could
substantially improve our ability to effectively monitor, manage and assess aggregations. Focusing on the gaps would help answer important questions such as how
many fi sh can be removed safely from a fi shed aggregation, the economic value of
management, whether full aggregation protection may result in a signifi cant
improvement of the associated, non-aggregation, fi shery, and could explain why
some, such as Atlantic cod, are not recovering as predicted by fi sheries models
(Hutchings and Reynolds 2004 ).
8.7.1 Empirical Data on Effects of Fishing on Reproductive
Output and Fishery Modelling
Biological studies and theoretical considerations suggest that certain biological
attributes of fi shes could and sometimes do predispose some species to negative
impacts on reproductive output brought about by aggregation-fi shing or by related
disturbances. What little evidence there is, however, while suggestive, is inconclusive and focused studies are needed to test hypotheses regarding possible impacts.
What is clear is that a precautionary approach is needed because so little is known
about the subtleties of long-term effects of fi shing on reproductive output and how
such effect(s) might be mediated. We have only to consider the other animal taxa
and a few of the examples presented in this section to acknowledge the possibilities.
It is clearly a failing that fi shery models and management thinking rarely take such
actual and potential complexities of life history into account (Sadovy and Vincent
2002 , Sect. 8.4 ). For example, direct, observational and experimental studies on the
relationship between aggregation size, density, and reproductive activity would be
particularly useful for determining whether minimum aggregation sizes are necessary to maintain viable populations. While reproduction may well continue even in
much reduced populations, whether such could maintain a substantial fi shery at
historical levels seems unlikely based on what we currently know.
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
small numbers of fi sh concentrated briefl y in one small area can appear remarkable, even scientifi c workers newly exposed to aggregations may have little idea
about former abundances. As one specifi c example in reef fi sheries, young
researchers today in the Caribbean conducting UVC are often impressed to see a
few hundred Nassau grouper gathered in one aggregation at sites that just three
or four decades ago held tens of thousands of fi sh (YSM personal observation).
Old fi lm footage and verbal accounts of divers, biologists, or fi shermen who have
seen such spectacular biological events are particularly valuable for highlighting
such changes.
8.7 Data Gaps
Based on the above review, we identify key data gaps which, if addressed, could
substantially improve our ability to effectively monitor, manage and assess aggregations. Focusing on the gaps would help answer important questions such as how
many fi sh can be removed safely from a fi shed aggregation, the economic value of
management, whether full aggregation protection may result in a signifi cant
improvement of the associated, non-aggregation, fi shery, and could explain why
some, such as Atlantic cod, are not recovering as predicted by fi sheries models
(Hutchings and Reynolds 2004 ).
8.7.1 Empirical Data on Effects of Fishing on Reproductive
Output and Fishery Modelling
Biological studies and theoretical considerations suggest that certain biological
attributes of fi shes could and sometimes do predispose some species to negative
impacts on reproductive output brought about by aggregation-fi shing or by related
disturbances. What little evidence there is, however, while suggestive, is inconclusive and focused studies are needed to test hypotheses regarding possible impacts.
What is clear is that a precautionary approach is needed because so little is known
about the subtleties of long-term effects of fi shing on reproductive output and how
such effect(s) might be mediated. We have only to consider the other animal taxa
and a few of the examples presented in this section to acknowledge the possibilities.
It is clearly a failing that fi shery models and management thinking rarely take such
actual and potential complexities of life history into account (Sadovy and Vincent
2002 , Sect. 8.4 ). For example, direct, observational and experimental studies on the
relationship between aggregation size, density, and reproductive activity would be
particularly useful for determining whether minimum aggregation sizes are necessary to maintain viable populations. While reproduction may well continue even in
much reduced populations, whether such could maintain a substantial fi shery at
historical levels seems unlikely based on what we currently know.