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In May 2007, Flower Garden Banks National Marine Sanctuary received an FDA-confirmed report of ciguatera fish poisoning (CFP) resulting from human consumption of a gag grouper caught in the sanctuary.

CFP is caused by ciguatoxins, which are produced by microalgae in the genus Gambierdiscus, and subsequently bioaccumulate in the flesh of fish. Globally, CFP is the principal cause of non-bacterial illness associated with seafood consumption.

Views of 4 Gambierdiscus species viewed under a microscope
Gambierdiscus cells seen under a microscope. Image: NOAA CCFHR/Mark Vandersea

When consumed by humans, ciguatera toxin can cause a range of symptoms within 6-24 hours. These may include vomiting, diarrhea, abdominal pain, muscle cramps, headaches, profound fatigue, itching and tingling skin, and a reversal of hot and cold sensations.

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In response to this issue, the National Oceanic and Atmospheric Administration (NOAA) collected a sampling of fish, from the sanctuary and its immediate surroundings, for the U.S. Food and Drug Administration (FDA) to analyze.

Scientist collecting samples from fish to test for ciguatoxin.
Chris Loeffler, from FDA, collecting samples from fish collected as part of ciguatera studies. Image: FGBNMS/Eckert

The focus of the sampling was on large, carnivorous reef fish such as barracuda, hogfish, groupers, snappers, jacks and mackerel, since they are the most likely to have accumulated significant amounts of the ciguatera toxin. All told, 31 fish representing 12 different species were tested:

Amberjack, Barracuda, Gag Grouper, Jack Crevalle, Marbled Grouper, Red Snapper, Sand Tilefish, Scamp, Shark, Snowy Grouper, Vermillion Snapper, Yellowmouth Grouper

Red snapper with otolith removed
Chris Loeffler holds an otolith in his tweezers that has just been removed from the red snapper on the table.
Image: FGBNMS/Eckert

They took note of the length and weight of each fish, then took samples of tissue, liver and viscera for ciguatoxin analysis, and collected otoliths (ear bones) to age the fish that were sampled.

Of the 31 fish sampled, four individual specimens were found to contain ciguatera toxin above FDA recommended levels:

Marbled Grouper
Sand Tilefish

Marbled Grouper
Marbled Grouper was among the specimens found to have elevated levels of ciguatera toxin. Image: FGBNMS/Schmahl

NOAA's Center for Coastal Fisheries and Habitat Research (CCFHR) and FGBNMS scientists also used molecular assays to determine the presence of a diverse grouping of Gambierdiscus species in the sanctuary. G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri and Gambierdiscus ribotype 2 were all found on both East and West Flower Garden Banks, with G. ruetzleri also recorded from West Flower Garden Bank.

These species were distributed to depths of >135 feet (41m) and are the likely source of ciguatoxins entering the food chain. These are also the deepest record for CFP-causing organisms reported globally and indicate that deeper water habitats may be an unexpected source of toxins entering the food chain.

These findings were published in the journal Harmful Algae.

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On February 5, 2008 the FDA issued a letter of guidance to seafood processors that purchase fish caught near Flower Garden Banks National Marine Sanctuary. The letter recommended that processors avoid purchasing the following species of concern, listed in terms of specific ranges around the sanctuary.

Map with red and yellow circles around East Flower Garden, West Flower Garden, and Stetson Banks showing the 10 mile and 50 mile advisory zones identified by the FDA.
Gulf of Mexico map showing FDA Advisory Zones for fishes caught near the sanctuary. Click on the map for a larger image.

Within 10 miles of FGBNMS:

Marbled Grouper (Epinephelus inermis)
Hogfish (Lachnolaimus maximus)
Blackfin Snapper (Lutjanus buccanella)
Dog Snapper (Lutjanus jocu)
Gag Grouper (Mycteroperca microlepis)
Scamp Grouper (Mycteroperca phenax)
Yellowfin Grouper (Mycteroperca venenosa)

Within 50 miles of FGBNMS:

Yellow Jack (Caranx bartholomaei)
Horse-eye Jack (Caranx latus)
Black Jack (Caranx lugubris)
King Mackerel (Scomberomorus cavalla)
Amberjack (Seriola dumerili)
Barracuda (Sphyraena barracuda)

Close up map with red and yellow circles around East Flower Garden, West Flower Garden, and Stetson Banks showing the 10 mile and 50 mile advisory zones identified by the FDA.
Close up of the FDA Advisory Zones surrounding the sanctuary. Click on the map for a larger image.


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An updated document, Guidance for Industry: Purchasing Reef Fish Species Associated with the Hazard of Ciguatera Fish Poisoning, was issued in November 2013.

The sanctuary continues to work with the FDA to monitor levels of ciguatera toxin in fish.

More Information

Ciguatera Fish Poisoning in the Northwestern Gulf of Mexico (7MB pdf) - poster presented by Ryan Eckert at GCFI 2013

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