274
Y. Sadovy de Mitcheson and B. Erisman
Unfortunately, research specifi cally aimed at understanding the effects of
decreased aggregation sizes, or the extirpations of spawning aggregations, on the
structures and processes of marine ecosystems, or on the target fi sheries at nonaggregation times, is in its infancy (Chaps. 2 and 11 ). Certainly, there is anecdotal
evidence that aggregations can attract large biomasses of megafauna and that some
have long been in existence (Chap. 1 ).
8.7.7 Inclusion of Aggregation Sites as Key Biodiversity Areas
or ‘Indicators’ of Reef Fishery Condition
While aggregations are not routinely incorporated into marine protected area
design, their possible importance for ‘congregatory’ species that help to identify
important areas for biodiversity, is being evaluated. For example, the selection of
‘key biodiversity areas’ as a conservation tool was initially applied to terrestrial
species and the criteria used for evaluation address the vulnerability and irreplaceability of such sites (Eken et al. 2004 ) . For congregatory species, sites that hold
large proportions of the global population of a species on a regular basis and at
specifi c times might be considered irreplaceable. This has already been applied in
the case of birds for which the threshold is provisionally set at 1% of the global
population of the species. Such a criterion could apply to fi sh species with relatively
few transient aggregations. Considerably more information is needed to better
understand the importance of individual aggregation sites for this criterion to be
applied, however. The problem with site-only based protection of exploited species
is that it does not, alone, address the problem of overexploitation so could only be
one tool used in the case of most commercial fi shes that are fi shed on their
aggregations.
Aggregations have considerable potential to be used as markers of ecosystem, or
as indicators of general fi shery health (Chaps. 1 and 10 ), which would both highlight their importance and attract greater attention to them. While there are both
advantages and disadvantages of using aggregations as indicators, on balance information to date suggests that they appear to be a good indication of the condition of
related fi sheries: where there is heavy overfi shing, aggregations are small or
non-existent, whereas in relatively unfi shed or managed areas, they persist (Sadovy
de Mitcheson et al. 2008 , SCRFA Newsletter No. 12, May 2009 www.SCRFA.org ).
8.7.8 Perception and Education
Understanding fi sher perceptions of the success, or otherwise, of protected sites and
seasons is a crucial part of overall long-term acceptance and effectiveness of management measures. In one of the relatively few studies to directly address this, fi shers
Y. Sadovy de Mitcheson and B. Erisman
Unfortunately, research specifi cally aimed at understanding the effects of
decreased aggregation sizes, or the extirpations of spawning aggregations, on the
structures and processes of marine ecosystems, or on the target fi sheries at nonaggregation times, is in its infancy (Chaps. 2 and 11 ). Certainly, there is anecdotal
evidence that aggregations can attract large biomasses of megafauna and that some
have long been in existence (Chap. 1 ).
8.7.7 Inclusion of Aggregation Sites as Key Biodiversity Areas
or ‘Indicators’ of Reef Fishery Condition
While aggregations are not routinely incorporated into marine protected area
design, their possible importance for ‘congregatory’ species that help to identify
important areas for biodiversity, is being evaluated. For example, the selection of
‘key biodiversity areas’ as a conservation tool was initially applied to terrestrial
species and the criteria used for evaluation address the vulnerability and irreplaceability of such sites (Eken et al. 2004 ) . For congregatory species, sites that hold
large proportions of the global population of a species on a regular basis and at
specifi c times might be considered irreplaceable. This has already been applied in
the case of birds for which the threshold is provisionally set at 1% of the global
population of the species. Such a criterion could apply to fi sh species with relatively
few transient aggregations. Considerably more information is needed to better
understand the importance of individual aggregation sites for this criterion to be
applied, however. The problem with site-only based protection of exploited species
is that it does not, alone, address the problem of overexploitation so could only be
one tool used in the case of most commercial fi shes that are fi shed on their
aggregations.
Aggregations have considerable potential to be used as markers of ecosystem, or
as indicators of general fi shery health (Chaps. 1 and 10 ), which would both highlight their importance and attract greater attention to them. While there are both
advantages and disadvantages of using aggregations as indicators, on balance information to date suggests that they appear to be a good indication of the condition of
related fi sheries: where there is heavy overfi shing, aggregations are small or
non-existent, whereas in relatively unfi shed or managed areas, they persist (Sadovy
de Mitcheson et al. 2008 , SCRFA Newsletter No. 12, May 2009 www.SCRFA.org ).
8.7.8 Perception and Education
Understanding fi sher perceptions of the success, or otherwise, of protected sites and
seasons is a crucial part of overall long-term acceptance and effectiveness of management measures. In one of the relatively few studies to directly address this, fi shers