444
12 Species Case Studies
overfi shing and rebuild the stock by August of 2011. Currently, gag is included on
the International Union for the Conservation of Nature and Natural Resources
(IUCN) List of Threatened Species as a species of least concern (IUCN 2008 ) .
Coastal development and fi shery impacts adversely affect species in coastal
nursery habitats, from salt marshes and seagrass beds to oyster reefs, important to
juvenile gag. Destruction and pollution of juvenile habitat is of signifi cant concern
for its infl uence on year-class strength (Coleman et al. 1999, 2000 ) . There is considerable concern now that red tide events along the west Florida shelf during the mid2000s have had a signifi cant negative effect on year class strength that has
reverberated through the fi shery. The red tide event of 2005 in the eastern Gulf of
Mexico is thought to have added 18% mortality to fi shing and natural mortality
(GMFMC 2009 ) .
12.7.5 Conservation Action and Recommendations
In the mid 1990s, Coleman et al. 1996 reported on the disturbing decline in the
proportion of male gag at the same time the National Marine Fisheries Service reported
signifi cant declines in gag stocks, suggesting that the species was approaching an
“overfi shed” condition (Schirripa and Legault 1997 ) . This set in motion a series of
events for the Gulf of Mexico Fishery Management Council that resulted in the establishment of two marine reserves, Madison Swanson Marine Reserve and Steamboat
Lumps Marine Reserve, the fi rst ones in the Gulf of Mexico (GMFMC 1999 ) . The
research conducted in these reserves has relied heavily on the input and participation
of commercial and recreational fi shers, resulting in signifi cant acceptance by those
involved. Results had initially been promising, indicating that males are remaining on
site long after the spawning season, and that the catch per unit area of male gag within
reserve boundaries is much higher than that in reference sites outside of the reserves
(CCK and FCC unpublished data). This case is signifi cant because (1) it was the fi rst
time that behavioural aspects of exploited stocks were considered, particularly the
social structure that infl uences sex change, and (2) involvement of commercial fi shers
has led to signifi cant acceptance, even by those strongly opposed to their formation
(Neils 2003 ) . While the positive effects of reserves appeared in a relatively short
period of time and were believed to be due to strong enforcement, subsequently
enforcement has been uneven and the disappearance of positive results largely attributed to lack of enforcement after Hurricanes Ivan in 2004, as well as Hurricanes
Katrina, and Rita in 2005, when enforcement agents were otherwise occupied.
To foster conservation of the gag, there is a need to initiate broad studies of the
behaviour, genetics and physiology of sex reversal, maturation and migration, timing and control of sex reversal, formation of shallow pre-spawning aggregations,
and movement of fi sh to spawning sites for gag. While Koenig and Coleman ( 1998 )
started and continue to monitor an index of abundance for juvenile gag in the early
1990s and from these data, have been able to identify strong year classes. There is a
12 Species Case Studies
overfi shing and rebuild the stock by August of 2011. Currently, gag is included on
the International Union for the Conservation of Nature and Natural Resources
(IUCN) List of Threatened Species as a species of least concern (IUCN 2008 ) .
Coastal development and fi shery impacts adversely affect species in coastal
nursery habitats, from salt marshes and seagrass beds to oyster reefs, important to
juvenile gag. Destruction and pollution of juvenile habitat is of signifi cant concern
for its infl uence on year-class strength (Coleman et al. 1999, 2000 ) . There is considerable concern now that red tide events along the west Florida shelf during the mid2000s have had a signifi cant negative effect on year class strength that has
reverberated through the fi shery. The red tide event of 2005 in the eastern Gulf of
Mexico is thought to have added 18% mortality to fi shing and natural mortality
(GMFMC 2009 ) .
12.7.5 Conservation Action and Recommendations
In the mid 1990s, Coleman et al. 1996 reported on the disturbing decline in the
proportion of male gag at the same time the National Marine Fisheries Service reported
signifi cant declines in gag stocks, suggesting that the species was approaching an
“overfi shed” condition (Schirripa and Legault 1997 ) . This set in motion a series of
events for the Gulf of Mexico Fishery Management Council that resulted in the establishment of two marine reserves, Madison Swanson Marine Reserve and Steamboat
Lumps Marine Reserve, the fi rst ones in the Gulf of Mexico (GMFMC 1999 ) . The
research conducted in these reserves has relied heavily on the input and participation
of commercial and recreational fi shers, resulting in signifi cant acceptance by those
involved. Results had initially been promising, indicating that males are remaining on
site long after the spawning season, and that the catch per unit area of male gag within
reserve boundaries is much higher than that in reference sites outside of the reserves
(CCK and FCC unpublished data). This case is signifi cant because (1) it was the fi rst
time that behavioural aspects of exploited stocks were considered, particularly the
social structure that infl uences sex change, and (2) involvement of commercial fi shers
has led to signifi cant acceptance, even by those strongly opposed to their formation
(Neils 2003 ) . While the positive effects of reserves appeared in a relatively short
period of time and were believed to be due to strong enforcement, subsequently
enforcement has been uneven and the disappearance of positive results largely attributed to lack of enforcement after Hurricanes Ivan in 2004, as well as Hurricanes
Katrina, and Rita in 2005, when enforcement agents were otherwise occupied.
To foster conservation of the gag, there is a need to initiate broad studies of the
behaviour, genetics and physiology of sex reversal, maturation and migration, timing and control of sex reversal, formation of shallow pre-spawning aggregations,
and movement of fi sh to spawning sites for gag. While Koenig and Coleman ( 1998 )
started and continue to monitor an index of abundance for juvenile gag in the early
1990s and from these data, have been able to identify strong year classes. There is a