255
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
Domeier 2005 ) . Satellite imagery (e.g. Google Earth) provides a bird’s eye view of
fi shing areas, increasing the likelihood of locating the spawning grounds of target
species once the physical attributes of such sites are better understood. The live fi sh
trade industry has used helicopters and planes to seek concentrations of fi shing
activity at aggregations (Leban Gisawa personal communication 2008, Bob Johannes
personal communication 2000). Increased range and capacity of large fi shing vessels, including those with live wells or viviers that can carry 15–20 mt, greatly
increase interest in commercial aggregation fi sheries (Johannes and Riepen 1995 ;
Johannes 1997 ) . Finally, the widespread introduction of ice plants in the Pacifi c to
encourage and facilitate market linkages is a favoured development tool often tied
to tuna licenses; iceplants greatly increase access to urban markets by remote fi shing communities to markets by providing temporary storage of fi sh until cargo vessels can take them to market, thereby opening up remote aggregations to commercial
exploitation (Being Yeeting personal communication 2009).
Certain gear types and fi shing practices have negative impacts on aggregation
sites and fi shes. Gill nets or bottom trawls damage important habitat features of
aggregation sites (Koslow et al. 1997 ; Hamilton et al. 2005 ) . In the Gulf of Mexico,
sites with high densities of Oculina coral hold high abundances of gag, Mycteroperca
microlepis , and scamp , Mycteroperca phenax , groupers; commercial trawl fi sheries
damage these spawning habitats, thereby accelerating population declines (Koenig
et al. 2000 ) . Dynamite is regularly applied to take milkfi sh , Chanos chanos , in the
Philippines (Table 8.1 ). Discards of sub-legal size fi sh may comprise a substantial
proportion of the recreational or commercial catch at aggregation sites but are often
associated with high post-release mortality due to barotrauma, gut-hooking, stress
and fatigue from prolonged handling times, or predation following release
(Burns et al. 2002 ; Rudershausen et al. 2007 ) .
Expansion of the SCUBA diving tourist industry, especially the increase in availability of inexpensive equipment (tanks, fi ns, underwater lights, etc.) has greatly contributed to the rise in the number of commercial, recreational, and artisanal fi shers and
divers who utilize this method to harvest fi shes from aggregations for sport or profi t
(e.g. Paz and Truly 2007 ) . Night-time spearfi shing, which involves compressed air
supplied via SCUBA or hookah, allows divers to easily harvest large numbers of resting fi shes at aggregation sites with minimal effort. This activity is widely illegal but
its prohibition is rarely enforced, and it is considered to be the major cause of aggregation declines in the Gulf of California and throughout the Pacifi c islands (Gillett
and Moy 2006 , www.seawatch.org ) (Fig. 8.9 ). Even the simple technology of a reliable d-cell battery torch (Toshiba and others), allowed night fi shing while snorkelling
in many areas of the Pacifi c (Pat Colin personal communication 2010).
8.4 Biological Effects of Fishing Spawning Aggregations
Animals congregate for numerous reasons. Conservation biologists and fi shery
managers, however, rarely concern themselves with the implications of grouping for
conservation action (Reed and Dobson 1993 ) . The one exception is in relation to the
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
Domeier 2005 ) . Satellite imagery (e.g. Google Earth) provides a bird’s eye view of
fi shing areas, increasing the likelihood of locating the spawning grounds of target
species once the physical attributes of such sites are better understood. The live fi sh
trade industry has used helicopters and planes to seek concentrations of fi shing
activity at aggregations (Leban Gisawa personal communication 2008, Bob Johannes
personal communication 2000). Increased range and capacity of large fi shing vessels, including those with live wells or viviers that can carry 15–20 mt, greatly
increase interest in commercial aggregation fi sheries (Johannes and Riepen 1995 ;
Johannes 1997 ) . Finally, the widespread introduction of ice plants in the Pacifi c to
encourage and facilitate market linkages is a favoured development tool often tied
to tuna licenses; iceplants greatly increase access to urban markets by remote fi shing communities to markets by providing temporary storage of fi sh until cargo vessels can take them to market, thereby opening up remote aggregations to commercial
exploitation (Being Yeeting personal communication 2009).
Certain gear types and fi shing practices have negative impacts on aggregation
sites and fi shes. Gill nets or bottom trawls damage important habitat features of
aggregation sites (Koslow et al. 1997 ; Hamilton et al. 2005 ) . In the Gulf of Mexico,
sites with high densities of Oculina coral hold high abundances of gag, Mycteroperca
microlepis , and scamp , Mycteroperca phenax , groupers; commercial trawl fi sheries
damage these spawning habitats, thereby accelerating population declines (Koenig
et al. 2000 ) . Dynamite is regularly applied to take milkfi sh , Chanos chanos , in the
Philippines (Table 8.1 ). Discards of sub-legal size fi sh may comprise a substantial
proportion of the recreational or commercial catch at aggregation sites but are often
associated with high post-release mortality due to barotrauma, gut-hooking, stress
and fatigue from prolonged handling times, or predation following release
(Burns et al. 2002 ; Rudershausen et al. 2007 ) .
Expansion of the SCUBA diving tourist industry, especially the increase in availability of inexpensive equipment (tanks, fi ns, underwater lights, etc.) has greatly contributed to the rise in the number of commercial, recreational, and artisanal fi shers and
divers who utilize this method to harvest fi shes from aggregations for sport or profi t
(e.g. Paz and Truly 2007 ) . Night-time spearfi shing, which involves compressed air
supplied via SCUBA or hookah, allows divers to easily harvest large numbers of resting fi shes at aggregation sites with minimal effort. This activity is widely illegal but
its prohibition is rarely enforced, and it is considered to be the major cause of aggregation declines in the Gulf of California and throughout the Pacifi c islands (Gillett
and Moy 2006 , www.seawatch.org ) (Fig. 8.9 ). Even the simple technology of a reliable d-cell battery torch (Toshiba and others), allowed night fi shing while snorkelling
in many areas of the Pacifi c (Pat Colin personal communication 2010).
8.4 Biological Effects of Fishing Spawning Aggregations
Animals congregate for numerous reasons. Conservation biologists and fi shery
managers, however, rarely concern themselves with the implications of grouping for
conservation action (Reed and Dobson 1993 ) . The one exception is in relation to the