Management and Conservation Considerations for
Long Tern Sustainable Use of Black Grouper
(Mycteroperca bonaci) in Belize
Mito Paz
Greenreef Belize
[email protected]
George Sedberry
Gray’s Reef National Marine Sanctuary
[email protected]
Groupers
• Noted Aggregation Spawners
– Large numbers
– Time & Site Specific
– Total Annual Reproductive output
• Spawning Event cued by:
– Lunar, Tidal or Seasonal phenomena
– Occurs in Reef Promontories
Metric Tons Landed
• Spawn in small sub-groups in a
spawning rush
• Eg. Nassau Grouper & Red hind
• Overfished and in Decline
3000
2500
2000
1500
1000
500
0
1970
1975
1980
1985
Year
1990
1995
2000
2005
Black Grouper
• Small aggregations (<200 fish) at many sites
• Less vulnerable to fishing: do not form huge (thousands of
individuals) at a few specific times and places
• Not cued to easily-located spatial (bathymetric) or temporal
(full moon) features (like Nassau grouper spawning)
• Spawn in male-female pairs within a large spag
• Less Vulnerable to fishing pressures
Black Grouper
•
•
•
•
Long-lived (Agemax = 33 + yr)
Slow-growing after age 10
Large size (TLmax = 152 cm)
Protogynous and late maturing
– Age50% maturity females = 5.2 y (826 mm TL)
– Age50% transition to male = 15.5 y (1214 mm TL)
• Multiple fisheries/gears on a single stock
– Subsistence, commercial, recreational
– Hook/line, traps, spear
• Predictable spawning aggregations?
Black Grouper (Mycteroperca bonaci)
NMFS Landings, U.S.
FAO Landings, WCA
Overfished and undergoing overfishing in SEUS
NMFS U.S. Landings (MT)
8
600
6
400
4
200
2
0
0
1990
1995
Year
2000
2005
FAO Atlantic Landingss (MT)
10
800
Fishing on Aggregation
• Alter sex ratio
• Interrupt Reproductive behaviour (social cues that
triggers sex change and spawning)
• Population size
• Result in spawning failure
Belize
Reef promontories have
historically been considered
important spawning grounds for
Nassau grouper and other
groupers and snappers,
including black grouper, dog
snapper, mutton snapper.
They are easy to locate from
crude bathymetric maps.
Turneffe Elbow
Bacalar Chico
Robinson
Belize
Sites
Include:
Angular
Points
Blunt
Points
Straight
Reef
Sanbar, Hol Chan
Cay Glory
• Spawning Site
Morphology
Robinson
Bacalar Chico
– North side of very angular reef promontories (e.g., Cay
Glory
– Blunt (rounded) promontories (e.g., Bacalar Chico)
– Elbows and sharp (<90°) bends in the reef around the
southern margin of the atolls (e.g., Half Moon Cay)
– Nearly straight stretches of shelf-edge reef (e.g.,
Robinson
• No particular reef type favored by black grouper;
promontories important for other groupers
What happens to black grouper in the
western Caribbean may affect recruitment to
Mexico and the SEUS
YOTO Drifter Tracks
28 May
5 May
10 Sep
What happens to black grouper in the
western Caribbean may affect recruitment to
Mexico and the SEUS
Spawning Site MPAs
Spawning Sites in Protected
Areas
Spawning Sites in NonProtected Areas
Rocky Point, Bacalar Chico
Sandbar, Hol Chan
Cay Glory
Gladden Spit
Nicholas Cay, Sapodilla
Dog Flea, Turneffe
Elbow, Turneffe
Sandbore, Lighthouse
Halfmoon, Lighthouse
South Point, Lighthouse
East Reef, Lighthouse
North Reef, Glovers
Middle Cay, Glovers
Long Cay, Glovers
Rise and Fall Bank, Sapodilla
Seal Cay, Sapodilla
Robinson, Ambergris C.
Cay Caulker
Goff’s Cay
Tobacco Cay
Mauger Cay, Turneffe
Mauger Cay (East), Turneffe
Soldier Cay, Turneffe
Rendezvous Point, Turneffe
SW End, Glovers
Calabash Cay, Turneffe
Crawl Cay, Turneffe
Deadman Cay, Turneffe
Ropewalk Cay, Turneffe
Reported Black Grouper
Aggregation Sites
28 Black grouper
Spawing Sites
15 are within MPA, notake spag sites and
natural monuments
13 are not protected
Other laws, regulations & policies
Fishing with nets, weirs or nets
within 100 yds
The use of SCUBA in scale-fish
fishing
Mesh size limits on nets, traps
and seines
Fish traps or fish pots at
spawning banks
Use of poison & explosives near
reefs
Use of spear guns in some MPAs
Black Grouper in Belize: Summary
• Small aggregations (<200 fish) at many sites
• Less vulnerable to fishing
• Not cued to easily-located spatial (bathymetric) or temporal
(full moon) features (like Nassau grouper spawning)
• Alternative grouper; not targeted by Nassau fishermen
• Afforded protection by MPAs (15 of 28 spawning sites) &
other laws and regulations
• Protogynous
• Males selectively removed
• Many small aggregations increase effect of sperm limitation, if
fishing effort remains constant or increases
• Some spawning sites missed because they have been
fished out. It is also possible that some spawning sites for
black grouper have not yet been discovered.
• Wary of divers, not as easily hooked or trapped
• Recreational fishing is increasing
• Black grouper populations in Belize are in good condition
Specific Considerations
• Network of no-take MPA protect black during spawning
• Wary of dives and avoid spear fishermen. Feeding make
them lose wary nature & become easy prey
• Continued monitoring of catch & effort and visual census of
population size needed
• Conservation of juvenile & adult habitats needed
• Characterizing spawning locations with rapid methods
• A comprehensive fishery statistics program is essential to
determine yield per recruit, virtual population and biomassbased stock assessment
Acknowledgements
• Award NA05NOS463148, National
Oceanography and Atmospheric
Administration (NOAA), U.S. Department
of Commerce
• Hol Chan MR
• Bacalar Chico MR
• Belize Fisheries Dept.