581
13 Conclusion
To move forward in our understanding of fi sh aggregations, it would be helpful
to study more model systems where individuals can be tracked and their reproductive
success output recorded. For example, studies of groupers have been very informative about travel costs and individual variation in behaviour, and studies of
Atlantic cod, Gadus morhua , in large tanks have been helpful for measuring
individual differences in behaviour and reproductive success.
Some questions can be addressed using a comparative approach by focusing on
better-documented species exposed to different levels of fi shing pressure and
policies in different areas. A good example would be the Nassau grouper for which
many aggregations are heavily fi shed (many extirpated), but some are relatively
intact. Comparing the timing, density, and behaviour of fi sh in exploited versus
protected or unexploited spawning aggregations would be instructive, as would
examining changes in spawning behaviour when traditional aggregations become
depleted or recover from over-fi shing, or when there are marked changes in population abundances or densities. Such studies would help elucidate the possible costs
and benefi ts of spawning in aggregations, and the implications of severely
reduced aggregation sizes. They might also shed light on the specifi c management
needs and effectiveness of management actions taken to protect species.
Quality of data and analysis is variable and available from many different sources.
Study of aggregating species is reported in a wide range of outputs, ranging from
publications by non-governmental organi za tions, governments, university theses,
intergovernmental organizations, consultancies, private companies, and individuals,
to biologists and others in the peer-reviewed scientifi c and other literature. While
much of this information is solid, the quality of non peer-reviewed ‘grey’ material
is variable, may not be subject to quality-control, and should be treated carefully
(Corlett 2011 ) . Whenever possible, original literature, rather than secondary citations,
should be referred to. On the other hand, we do not need to limit our information
sources to the classic channels. Suitably validated, as for example for fi sher interviews,
much can be learned from reports by recreational divers, dive guides and others
who spend a lot of time in the water.
13.5 Protection and Management of Aggregations
The negative impacts of fi shing appear to be substantially greater on transient than
on resident aggregating species and Chapter one pointed out differences between
resident and transient aggregations that have important conservation and management implications. The record shows that transient aggregators tend to need more
management attention than resident aggregators, for obvious reasons. Moreover,
when considering the establishment of MPAs to protect spawning populations,
multiple widespread resident aggregations can be protected by setting aside some
percentage of an overall area, whereas MPAs to protect transient aggregations must
be either very large or very well-placed, because the latter are relatively fewer and
sparser. Catchment areas become a critical factor in transient aggregators if the
scale of management efforts is to be appropriately determined, and other links may
13 Conclusion
To move forward in our understanding of fi sh aggregations, it would be helpful
to study more model systems where individuals can be tracked and their reproductive
success output recorded. For example, studies of groupers have been very informative about travel costs and individual variation in behaviour, and studies of
Atlantic cod, Gadus morhua , in large tanks have been helpful for measuring
individual differences in behaviour and reproductive success.
Some questions can be addressed using a comparative approach by focusing on
better-documented species exposed to different levels of fi shing pressure and
policies in different areas. A good example would be the Nassau grouper for which
many aggregations are heavily fi shed (many extirpated), but some are relatively
intact. Comparing the timing, density, and behaviour of fi sh in exploited versus
protected or unexploited spawning aggregations would be instructive, as would
examining changes in spawning behaviour when traditional aggregations become
depleted or recover from over-fi shing, or when there are marked changes in population abundances or densities. Such studies would help elucidate the possible costs
and benefi ts of spawning in aggregations, and the implications of severely
reduced aggregation sizes. They might also shed light on the specifi c management
needs and effectiveness of management actions taken to protect species.
Quality of data and analysis is variable and available from many different sources.
Study of aggregating species is reported in a wide range of outputs, ranging from
publications by non-governmental organi za tions, governments, university theses,
intergovernmental organizations, consultancies, private companies, and individuals,
to biologists and others in the peer-reviewed scientifi c and other literature. While
much of this information is solid, the quality of non peer-reviewed ‘grey’ material
is variable, may not be subject to quality-control, and should be treated carefully
(Corlett 2011 ) . Whenever possible, original literature, rather than secondary citations,
should be referred to. On the other hand, we do not need to limit our information
sources to the classic channels. Suitably validated, as for example for fi sher interviews,
much can be learned from reports by recreational divers, dive guides and others
who spend a lot of time in the water.
13.5 Protection and Management of Aggregations
The negative impacts of fi shing appear to be substantially greater on transient than
on resident aggregating species and Chapter one pointed out differences between
resident and transient aggregations that have important conservation and management implications. The record shows that transient aggregators tend to need more
management attention than resident aggregators, for obvious reasons. Moreover,
when considering the establishment of MPAs to protect spawning populations,
multiple widespread resident aggregations can be protected by setting aside some
percentage of an overall area, whereas MPAs to protect transient aggregations must
be either very large or very well-placed, because the latter are relatively fewer and
sparser. Catchment areas become a critical factor in transient aggregators if the
scale of management efforts is to be appropriately determined, and other links may