379
11 Management of Spawning Aggregations
variously implemented but some are subject to renewal each year rather than being
permanent measures. In 2009, in the southeastern United States, the South Atlantic
Fishery Management Council established a temporal closure from January to April
each year to protect spawning adults of grouper species ( Mycteroperca spp. and
Epinephelus spp.).
Permanent area closures can provide protection if aggregation sites are known
and can encompass many aggregation sites if the areas are large enough. There is a
higher overall fi shery advantage of permanent spatial closures compared to shortterm closures because the protected area can act as a source of recruits for a wide
range of species not otherwise protected by seasonal or short-term area closures.
Permanent MPAs can protect resident aggregations from fi shing, but may not be as
effective for transient aggregating species, because these fi sh may be vulnerable to
fi shing on the spawning migration routes outside the MPA (e.g. lane snapper,
Lutjanus synagris , in Cuba, Claro and Lindeman 2003 ) . Very large permanent
closures encompassing not only aggregation sites but a large part of the fi sh stock
can conserve populations and allow for spillover and recruitment subsidy, as well as
habitat protection, but do not alone control the remaining fi shery which can still
become overexploited. Aggregation sites that are used for spawning by single or
multiple species, many of them commercial, are known to occur in outer reef channels
and along outer reefs that drop-off into oceanic waters (Heyman and Kjerfve 2008 ;
Koenig et al. 2000 ; Sadovy de Mitcheson et al. 2008 ) . These offshore habitats are
not routinely included in protected area designations, or otherwise managed. In many
areas, deep slope or drop off areas may be important for deepwater assemblages,
may include migration pathways (Starr et al. 2007 ) , and may represent the last
refuge for species heavily fi shed in shallow water, so merit more attention from
MPA planners. In 1987, the Cayman Islands’ Department of the Environment began
monitoring Nassau grouper populations because fi shers reported smaller fi sh and
lower catches. Monitoring at Little Cayman’s west end began in 2002 when large
numbers of Nassau groupers were harvested relative to the total numbers present.
This aggregation site, along with seven others, was protected under legislation
enacted in 2003 that prohibits fi shing year-round within the protected areas and has
been regularly monitored by a dedicated group of researchers. The protection is
likely to be an important factor in stabilizing or even increasing numbers of fi sh at
the site. Numbers now appear to be stable and there are indications of an increase
(Whaylen et al. 2007 ) .
The locations of some aggregations may shift short distances of up to several
hundred metres between years (Kadison et al. 2007 ; Heyman and Kjerfve 2008 ) , or
the exact location and size of an aggregation may not be fully documented prior to
introduction of site-based measures. Protected areas need to be of an adequate size
to include a buffer area around the spawning area to allow for such variability and
uncertainty (see also ‘staging areas’ Chap. 2 ). For example, in the Florida Keys
there was insuffi cient spatial information on a black grouper ( Mycteroperca bonaci )
aggregation site when the boundaries for a no-take MPA were being set. Subsequent
research determined that the aggregation occurred in deeper waters outside of the
MPA boundary (Eklund et al. 2000 ) , thus the original MPA afforded little protection
11 Management of Spawning Aggregations
variously implemented but some are subject to renewal each year rather than being
permanent measures. In 2009, in the southeastern United States, the South Atlantic
Fishery Management Council established a temporal closure from January to April
each year to protect spawning adults of grouper species ( Mycteroperca spp. and
Epinephelus spp.).
Permanent area closures can provide protection if aggregation sites are known
and can encompass many aggregation sites if the areas are large enough. There is a
higher overall fi shery advantage of permanent spatial closures compared to shortterm closures because the protected area can act as a source of recruits for a wide
range of species not otherwise protected by seasonal or short-term area closures.
Permanent MPAs can protect resident aggregations from fi shing, but may not be as
effective for transient aggregating species, because these fi sh may be vulnerable to
fi shing on the spawning migration routes outside the MPA (e.g. lane snapper,
Lutjanus synagris , in Cuba, Claro and Lindeman 2003 ) . Very large permanent
closures encompassing not only aggregation sites but a large part of the fi sh stock
can conserve populations and allow for spillover and recruitment subsidy, as well as
habitat protection, but do not alone control the remaining fi shery which can still
become overexploited. Aggregation sites that are used for spawning by single or
multiple species, many of them commercial, are known to occur in outer reef channels
and along outer reefs that drop-off into oceanic waters (Heyman and Kjerfve 2008 ;
Koenig et al. 2000 ; Sadovy de Mitcheson et al. 2008 ) . These offshore habitats are
not routinely included in protected area designations, or otherwise managed. In many
areas, deep slope or drop off areas may be important for deepwater assemblages,
may include migration pathways (Starr et al. 2007 ) , and may represent the last
refuge for species heavily fi shed in shallow water, so merit more attention from
MPA planners. In 1987, the Cayman Islands’ Department of the Environment began
monitoring Nassau grouper populations because fi shers reported smaller fi sh and
lower catches. Monitoring at Little Cayman’s west end began in 2002 when large
numbers of Nassau groupers were harvested relative to the total numbers present.
This aggregation site, along with seven others, was protected under legislation
enacted in 2003 that prohibits fi shing year-round within the protected areas and has
been regularly monitored by a dedicated group of researchers. The protection is
likely to be an important factor in stabilizing or even increasing numbers of fi sh at
the site. Numbers now appear to be stable and there are indications of an increase
(Whaylen et al. 2007 ) .
The locations of some aggregations may shift short distances of up to several
hundred metres between years (Kadison et al. 2007 ; Heyman and Kjerfve 2008 ) , or
the exact location and size of an aggregation may not be fully documented prior to
introduction of site-based measures. Protected areas need to be of an adequate size
to include a buffer area around the spawning area to allow for such variability and
uncertainty (see also ‘staging areas’ Chap. 2 ). For example, in the Florida Keys
there was insuffi cient spatial information on a black grouper ( Mycteroperca bonaci )
aggregation site when the boundaries for a no-take MPA were being set. Subsequent
research determined that the aggregation occurred in deeper waters outside of the
MPA boundary (Eklund et al. 2000 ) , thus the original MPA afforded little protection