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FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS. Earth From Space. Satellite Image of North Central Gulf of Mexico. MS. AL. shelf. LA. TX. FL. shelf. shelf. Tan areas reflect continental shelf of Northern Gulf of Mexico. Ecosystem based fisheries management.
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FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS
MS AL shelf LA TX 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
Food Pyramid for the Oceans APEX or Top Predator Sharks Tunas and Mackerel Wolf of the ocean Anchovy-Sardines Cows of the ocean Copepods DIATOMS - Plants of the ocean
NMFS Bottom Longline • Fishery independent bottom longline database: 1995 • Gulf wide random site selection out to 400 meters
Blocks 1,2 West of Mobile Bay Block 3, 4, East of Mobile Bay Blue Line -North South Transect
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
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
Tag Tetracycline is injected as a marker
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
Rarely sea turtle like this Loggerhead are fouled hooked on long-line
Juvenile Tiger shark caught ¼ mile off Alabama-Florida line
Satellite Tags DISL
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