287
9 Studying and Monitoring Aggregating Species
instrumented to measure physical parameters while fi shes are being tagged with
acoustic and conventional methods to examine adult connectivity.
Despite progress, there is still a need to increase and improve overall work on
aggregations to assess effects of fi shing or track the outcomes of management
action. In some cases the existence of aggregations is proposed based on unclear
criteria (Chap. 1 ). Often information from fi shers is accepted as defi nitive regarding
aggregations, migration pathways, and other aspects of biology important for
management without due diligence. Such information is still extremely valuable
and should be documented, but cannot be treated as scientifi c fact until properly
validated.
Interest in spawning aggregations has increased, but attention to other aspects of
life history is also necessary to understand how to manage such species. Early life
histories (from fertile egg to recruiting juvenile) and oceanography, for example,
receive little attention (Chaps. 6 and 7 ). In efforts to identify whether specifi c
conditions apply at aggregation sites, areas without aggregations are typically not
used as control or comparative sites, to see if differences exist. Moreover, sites with
aggregation are often not examined outside of aggregation periods. Researchers
should be concerned with the entire life history of the species within an oceanographic framework (Lindemann et al. 2000 ) .
9.2 Types of Information Needed for Work
on Spawning Aggregations
Table 9.1 indicates some of the aspects of aggregations of probable interest to
researchers and managers and identifi es methods likely to prove useful in examining these subjects. Subsequently, each method is briefl y described with more
detailed notes regarding some of the methods. Methods useful for documenting
fi sheries and their long term monitoring and preservation are dealt with in
Chaps. 10 and 11 .
9.3 Fishery Dependent and Independent Methods
Some types of aggregation work can be undertaken without collection of fi sh by
fi shers or researchers. While the uncontrolled commercial exploitation of aggregations is generally not benefi cial in the long term, if fi shing activities are being carried out it would be counterproductive for researchers to pass up the opportunity to
sample and otherwise learn from the capture of fi sh. Table 9.1 has an indication of
whether a particular type of study method is fi shery-dependent (relies on capture of
fi sh) or independent of fi shing.
9 Studying and Monitoring Aggregating Species
instrumented to measure physical parameters while fi shes are being tagged with
acoustic and conventional methods to examine adult connectivity.
Despite progress, there is still a need to increase and improve overall work on
aggregations to assess effects of fi shing or track the outcomes of management
action. In some cases the existence of aggregations is proposed based on unclear
criteria (Chap. 1 ). Often information from fi shers is accepted as defi nitive regarding
aggregations, migration pathways, and other aspects of biology important for
management without due diligence. Such information is still extremely valuable
and should be documented, but cannot be treated as scientifi c fact until properly
validated.
Interest in spawning aggregations has increased, but attention to other aspects of
life history is also necessary to understand how to manage such species. Early life
histories (from fertile egg to recruiting juvenile) and oceanography, for example,
receive little attention (Chaps. 6 and 7 ). In efforts to identify whether specifi c
conditions apply at aggregation sites, areas without aggregations are typically not
used as control or comparative sites, to see if differences exist. Moreover, sites with
aggregation are often not examined outside of aggregation periods. Researchers
should be concerned with the entire life history of the species within an oceanographic framework (Lindemann et al. 2000 ) .
9.2 Types of Information Needed for Work
on Spawning Aggregations
Table 9.1 indicates some of the aspects of aggregations of probable interest to
researchers and managers and identifi es methods likely to prove useful in examining these subjects. Subsequently, each method is briefl y described with more
detailed notes regarding some of the methods. Methods useful for documenting
fi sheries and their long term monitoring and preservation are dealt with in
Chaps. 10 and 11 .
9.3 Fishery Dependent and Independent Methods
Some types of aggregation work can be undertaken without collection of fi sh by
fi shers or researchers. While the uncontrolled commercial exploitation of aggregations is generally not benefi cial in the long term, if fi shing activities are being carried out it would be counterproductive for researchers to pass up the opportunity to
sample and otherwise learn from the capture of fi sh. Table 9.1 has an indication of
whether a particular type of study method is fi shery-dependent (relies on capture of
fi sh) or independent of fi shing.