435
12 Species Case Studies
there have been substantial declines in catch, catch per unit effort and mean body
size at aggregations (Bush et al. 2006). In The Bahamas, although there is still a
viable fi shery, reported annual landings have dropped at least threefold over
approximately 15 years (most recent data suggest about 400 tonnes-Bahamas
Department of Marine Resources) and the status of most aggregations is unknown.
Throughout its entire range, more than half of all known aggregation sites (n » 100
in total) are believed to be extirpated (Sadovy and Eklund 1999 ; Sadovy de
Mitcheson et al. 2008 ) . In the Turks and Caicos, although there is relatively little
focus on the Nassau grouper at present, there is considerable consumer interest
(expected to grow along with tourism) in the species and a signifi cant proportion
of fi sh in one recent study is already taken below sexual maturation. Therefore
pressure on the Nassau grouper in this country is expected to grow, and the species
is not yet managed (Landsman et al. 2009 ) .
Some aggregations fi shed to extirpation have not recovered in decades (Beets
and Friedlander 1992 ) , and it is possible that aggregations persist when younger fi sh
learn migration routes by following older fi sh to traditional spawning sites. When
the older fi sh are fi shed out, this “traditional knowledge” may be lost and the aggregation may be incredibly slow to reform. No aggregation, once extirpated, has ever
been observed to recover although there are recent indications of a possible increase
in numbers at one aggregation site in the US Virgin Islands (Rick Nemeth, personal
observation). If true, this means, among other things, that restocking is unlikely to
be an appropriate recovery strategy for the species.
The Nassau grouper is recognized for its economic importance for dive tourism
and encounters with such large groupers are very appealing to divers (Rudd and
Tupper 2002 ) . Sala et al. ( 2001 ) estimated that tourist diving on grouper spawning
aggregations would produce 20 times the income produced from fi shing it in Belize.
While it is suggested that the impacts of divers on spawning might be acceptably
low, a more detailed analysis of Nassau grouper is recommended before the impacts
of divers can be understood (Heyman et al. 2010 ) . Certainly large schools of fi sh
just prior to spawning are infl uenced by divers in the water and slowly start to move
away from them (YS, personal observation 2006).
Nassau grouper are fi shed commercially and recreationally by handline, longline,
fi sh traps, spear guns, and gillnets. Spawning aggregations are heavily targeted,
often yield most of the annual catches and are mainly exploited by handlines or fi sh
traps, although gillnets are also used in Mexico IUCN red list assessment (Albins
et al. 2003). Fishery-dependent data in the United States showed marked declines
and severe fl uctuations in catch rates through the 1980s resulting in a ban on retention of Nassau grouper in 1990. The species is variously protected in Belize,
Bahamas, Bermuda, Cayman Islands, Cuba, Puerto Rico, United States Virgin
Islands, and Mexico. In spite of such protection enforcement is wanting in most
locations (Sadovy and Eklund 1999 ; Sala et al. 2001 ; Whaylen et al. 2004 ; AguilarPerera and Aguilar-Dávila 2007 ; Sadovy de Mitcheson et al. 2008 ; Aguilar-Perera
et al. 2009 ; Claro et al. 2009 ; www.SCRFA.org database) (Table 12.1 ). There is a
need for both national and regional management measures for recovery of this
threatened species (García-Moliner and Sadovy 2008 ; Albins et al. 2009 ) .
12 Species Case Studies
there have been substantial declines in catch, catch per unit effort and mean body
size at aggregations (Bush et al. 2006). In The Bahamas, although there is still a
viable fi shery, reported annual landings have dropped at least threefold over
approximately 15 years (most recent data suggest about 400 tonnes-Bahamas
Department of Marine Resources) and the status of most aggregations is unknown.
Throughout its entire range, more than half of all known aggregation sites (n » 100
in total) are believed to be extirpated (Sadovy and Eklund 1999 ; Sadovy de
Mitcheson et al. 2008 ) . In the Turks and Caicos, although there is relatively little
focus on the Nassau grouper at present, there is considerable consumer interest
(expected to grow along with tourism) in the species and a signifi cant proportion
of fi sh in one recent study is already taken below sexual maturation. Therefore
pressure on the Nassau grouper in this country is expected to grow, and the species
is not yet managed (Landsman et al. 2009 ) .
Some aggregations fi shed to extirpation have not recovered in decades (Beets
and Friedlander 1992 ) , and it is possible that aggregations persist when younger fi sh
learn migration routes by following older fi sh to traditional spawning sites. When
the older fi sh are fi shed out, this “traditional knowledge” may be lost and the aggregation may be incredibly slow to reform. No aggregation, once extirpated, has ever
been observed to recover although there are recent indications of a possible increase
in numbers at one aggregation site in the US Virgin Islands (Rick Nemeth, personal
observation). If true, this means, among other things, that restocking is unlikely to
be an appropriate recovery strategy for the species.
The Nassau grouper is recognized for its economic importance for dive tourism
and encounters with such large groupers are very appealing to divers (Rudd and
Tupper 2002 ) . Sala et al. ( 2001 ) estimated that tourist diving on grouper spawning
aggregations would produce 20 times the income produced from fi shing it in Belize.
While it is suggested that the impacts of divers on spawning might be acceptably
low, a more detailed analysis of Nassau grouper is recommended before the impacts
of divers can be understood (Heyman et al. 2010 ) . Certainly large schools of fi sh
just prior to spawning are infl uenced by divers in the water and slowly start to move
away from them (YS, personal observation 2006).
Nassau grouper are fi shed commercially and recreationally by handline, longline,
fi sh traps, spear guns, and gillnets. Spawning aggregations are heavily targeted,
often yield most of the annual catches and are mainly exploited by handlines or fi sh
traps, although gillnets are also used in Mexico IUCN red list assessment (Albins
et al. 2003). Fishery-dependent data in the United States showed marked declines
and severe fl uctuations in catch rates through the 1980s resulting in a ban on retention of Nassau grouper in 1990. The species is variously protected in Belize,
Bahamas, Bermuda, Cayman Islands, Cuba, Puerto Rico, United States Virgin
Islands, and Mexico. In spite of such protection enforcement is wanting in most
locations (Sadovy and Eklund 1999 ; Sala et al. 2001 ; Whaylen et al. 2004 ; AguilarPerera and Aguilar-Dávila 2007 ; Sadovy de Mitcheson et al. 2008 ; Aguilar-Perera
et al. 2009 ; Claro et al. 2009 ; www.SCRFA.org database) (Table 12.1 ). There is a
need for both national and regional management measures for recovery of this
threatened species (García-Moliner and Sadovy 2008 ; Albins et al. 2009 ) .