Transcript FisheriesmgtCOSEE2010

FISHERIES MANAGEMENT AND
THE ROLE OF
APEX PREDATORS
Earth From Space
Satellite Image of North Central Gulf of Mexico
MS
AL
shelf
TX
LA
FL
shelf
shelf
Tan areas reflect continental shelf
of Northern Gulf of Mexico
Ecosystem based fisheries management
• Gulf of Mexico: a large
marine ecosystem (LME)
• An ecosystem: “the
complex of a community
of organisms and its
environment functioning
as an ecological unit”
• How do we understand
an ecosystem?
Link (2002)
Link J. 2002. Does food web theory work
for marine ecosystems? Marine Ecology
Progress Series 230: 1-9.
Images from Large Marine Ecosystem project, Sherman et al.
Red Drum or redfish were nearly depleted
In the 1980’s
Graduate student Matt Kenworthy studies red drum
APEX PREDATORS IN THE
NORTHERN GULF OF MEXICO
Food Pyramid for
the Oceans
Sharks
Tunas and Mackerel
Anchovy-Sardines
Copepods
DIATOMS - Plants of the ocean
NMFS Bottom Longline
• Fishery independent bottom longline database: 1995
• Gulf wide random site selection out to 400 meters
Alabama
Mississippi
Louisanna
30
Texas
Florida
28
1200 m isobath
26
24
98
US Exclusive Economic Zone (EEZ)
96
94
92
90
88
86
84
82
Blacktip shark
Carcharhinus limbatus
30
28
26
24
96
94
92
90
88
86
84
82
31
Mobile Bay
Florida
Mississippi
1
2
3
4
30
10M
29
89
20M
Blocks 1,2 West of Mobile Bay
Block 3, 4, East of Mobile Bay
Blue Line -North South Transect
88
87
31
Mobile Bay
FL
MS
30.5
20 m
30
2009 Survey
29.5
200 m
29
89
88.5
88
87.5
87
Blacktip Shark
Torpedo shaped for speed
Camouflaged top and bottom
Ampullae of Lroenzini-electric fields
1/3 to 2/3 of brain devoted to smell
Mirror like reflective membrane to
enhance light gathering
Teeth are modified scales
Buoy
Long-line
Hooks
Shark Bait
Long-line gangets with baited hooks
Retrieving long-line with Shark
Hammerhead Shark
Sharks are brought on board to
collect data
Tag has a number that corresponds to a
data sheet and statement that says REWARD
with phone number
Tagging Shark
Tag
Species Identification, Sex and Weight
Tag
Tetracycline is injected as a marker
Marcus Dryman with Blacknose shark
Not all sharks survive being
caught on the long-line, many
Samples from stomach to liver
tissue are taken for further
analysis
Atlantic Sharpnose sharks have a
low tolerance for oxygen deprivation
Atlantic Sharpnose embryonic sharks, 4 in each uterus
8 total
Southern Stingray
Circle hooks cause less
mortality
Red Drum are often caught on the long-line
Rarely sea turtle like this Loggerhead are fouled hooked on long-line
Nurse shark – hook being cut off to release shark
Juvenile Tiger shark
caught ¼ mile off
Alabama-Florida line
Tiger shark tagged and released
Satellite Tags

DISL
Acoustic Tagging
We Are the Top Predators
Gulp!
Even sea birds fall prey to sharks
APEX predator – means being on the top of the food chain
Explosion and sinking of oil well
Deep Horizon
References That You Can Review
Current-Journal of Marine Education Vol. 18 Number 1 2002
Harden, G. 1968. “The Tragedy of the Commons” Science
162:1243-1248
Husted, R., and R. Lent. “International Aspects of Atlantic
Highly Migratory Species Management”. Current 14:22-24
Richards, W.J. & Edwards, R.E. (1986) “Stocking To Restore of
Enhance Marine Fisheries” In : Fish Culture in Fisheries
Management pp.75-80 American Fisheries Society
Web sites: www.ifmt.nf.ca/mi-net/fishdeve/index
www.ncdmf.net
www.nmfs.noaa.gov/sfa/magact
www.vims.edu/bridge/archive0100
www.vims.edu/bridge/archive0299
http://www.cosee-gom.org
http://www.disl.org