FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS
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Transcript of FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS
• 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)
Ecosystem based fisheries management
Images from Large Marine Ecosystem project, Sherman et al.
Link J. 2002. Does food web theory work for marine ecosystems? Marine Ecology Progress Series 230: 1-9.
Red Drum or redfish were nearly depletedIn the 1980’s
Graduate student Matt Kenworthy studies red drum
Food Pyramid forthe Oceans
DIATOMS - Plants of the ocean
Copepods
Anchovy-Sardines
Cow
s of
the
ocea
n
Tunas and Mackerel
Wol
f of t
he o
cean
Sharks
APEX or Top Predator
9 8 9 6 9 4 9 2 9 0 8 8 8 6 8 4 8 22 4
2 6
2 8
3 0 Texas
LouisannaMississippi
Alabama
Florida
US Exclusive Economic Zone (EEZ)
1200 m isobath
NMFS Bottom Longline
• Fishery independent bottom longline database: 1995
• Gulf wide random site selection out to 400 meters
8 9 8 8 8 72 9
3 0
3 1
1 2 3 4
M i s s i s s i p p i F l o r i d a
1 0 M 2 0 M
M o b i l e B a y
Blocks 1,2 West of Mobile BayBlock 3, 4, East of Mobile BayBlue Line -North South Transect
8 9 8 8 . 5 8 8 8 7 . 5 8 72 9
2 9 . 5
3 0
3 0 . 5
3 1
M S F L
M o b i l e B a y
2 0 m
2 0 0 m
2009 Survey
Blacktip SharkBlacktip Shark
Torpedo shaped for speedTorpedo shaped for speedCamouflaged top and bottomCamouflaged top and bottomAmpullae of Lroenzini-electric fieldsAmpullae of Lroenzini-electric fields1/3 to 2/3 of brain devoted to smell1/3 to 2/3 of brain devoted to smellMirror like reflective membrane toMirror like reflective membrane toenhance light gatheringenhance light gathering
Teeth are modified scalesTeeth are modified scales
Not all sharks survive beingcaught on the long-line, many Samples from stomach to livertissue are taken for further analysis
Atlantic Sharpnose sharks have a low tolerance for oxygen deprivation
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