FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS

FISHERIES MANAGEMENT AND THE ROLE OF APEX PREDATORS

Earth From Space

Satellite Image of North Central Gulf of Mexico

MS TX LA AL shelf FL 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

EX AP Food Pyramid for the Oceans or p To Tunas and Mackerel Anchovy-Sardines Copepods Co ws of the oc ea n Wo lf o f th eo ce an or at ed Pr Sharks DIATOMS - Plants of the ocean

NMFS Bottom Longline • Fishery independent bottom longline database: 1995 • Gulf wide random site selection out to 400 meters

Blacktip shark Carcharhinus limbatus

Blocks 1, 2 West of Mobile Bay Block 3, 4, East of Mobile Bay Blue Line -North South Transect

2009 Survey

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

http: //www. cosee-gom. org http: //www. disl. org

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/archive 0100 www. vims. edu/bridge/archive 0299