Regional Variations in the Risk and Severity of Ciguatera Caused by Eating Moray Eels

Abstract

Moray eels (Gymnothorax species) from tropical waters have long been known to be high-risk species, and the consumption of particularly the viscera or ungutted eels can result in severe ciguatera (known as Gymnothorax or moray eel poisoning), characterized by prominent neurological features. In this review, the main objective was to describe the risk and severity of ciguatera caused by eating moray eels in different parts of the world. Moray eels can accumulate very high ciguatoxin (CTX) levels in the flesh and particularly the liver. Therefore, even the smaller ones can be toxic and the consumption of an average portion (particularly liver) can result in severe or fatal ciguatera. Moray eels (particularly when ungutted) must never be served in gatherings since they can cause mass poisoning because of their large sizes and high CTX levels. Apart from regulatory measures restricting or excluding access, the public should be repeatedly warned to avoid eating moray eels.

Ciguatoxin Detection in Flesh and Liver of Relevant Fish Species from the Canary Islands

“…Moray eels are demersal and great hunters and are well known to produce CP outbreaks worldwide [18]. The presence of Caribbean ciguatoxin-1 (C-CTX1) [19,20] by liquid chromatography mass spectrometry (LC-MS/MS) in a black moray eel from the Canary Islands [21] has been confirmed.…”

Moray eels are more common on coral reefs subject to higher human pressure in the greater Caribbean

“…Morays comprise nearly 200 species of functionally unique reef predators, with their elongate bodies and raptorial pharyngeal jaws enabling them to ambush relatively large fish, crustaceans, and octopuses in habitats with complex structure (Chan, 2017;Gilbert et al, 2005;Mehta and Wainwright, 2007;Mouillot et al, 2013). Morays have little to no commercial value because they are generally unpalatable and can contain toxic levels of ciguatera (Chan, 2017). We hypothesize that size and proximity of markets and closing reefs to fishing would therefore have no effect on morays.…”

“…This pattern has been observed on coral reefs worldwide, affecting commercially exploited predator taxa ranging from groupers to sharks Graham et al, 2017;MacNeil et al, 2020;. Moray eels (Family Muraenidae; hereafter referred to as 'morays') are not readily detected in conventional reef surveys, and it is unknown how they respond to human impacts on coral reef systems (Chan, 2017;Gilbert et al, 2005;Mehta and Wainwright, 2007;Mouillot et al, 2013). Morays comprise nearly 200 species of functionally unique reef predators, with their elongate bodies and raptorial pharyngeal jaws enabling them to ambush relatively large fish, crustaceans, and octopuses in habitats with complex structure (Chan, 2017;Gilbert et al, 2005;Mehta and Wainwright, 2007;Mouillot et al, 2013).…”

“…Moray eels (Family Muraenidae; hereafter referred to as 'morays') are not readily detected in conventional reef surveys, and it is unknown how they respond to human impacts on coral reef systems (Chan, 2017;Gilbert et al, 2005;Mehta and Wainwright, 2007;Mouillot et al, 2013). Morays comprise nearly 200 species of functionally unique reef predators, with their elongate bodies and raptorial pharyngeal jaws enabling them to ambush relatively large fish, crustaceans, and octopuses in habitats with complex structure (Chan, 2017;Gilbert et al, 2005;Mehta and Wainwright, 2007;Mouillot et al, 2013). Morays have little to no commercial value because they are generally unpalatable and can contain toxic levels of ciguatera (Chan, 2017).…”

Critical Review and Conceptual and Quantitative Models for the Transfer and Depuration of Ciguatoxins in Fishes

“…from the Republic of Kiribati [ 87 ]. Such high toxin concentrations are likely life-threatening, with probably more deaths from ciguatera in the Pacific caused by moray eels than any other fish [ 165 ]. Possibly moray eels can accumulate such high concentrations through a resistance mechanism [ 87 ], not possessed to the same degree by other fish species [ 140 , 166 , 167 ].…”