How safe is it to eat lionfish?
Ciguatera fish poisoning (CFP) is one of the most common marine poisons in the world. There are more than fifty thousand cases reported each year, though the true number of poisonings has been estimated to be closer to five hundred thousand. Seventy percent of those who live in the Pacific islands may have been poisoned at least once. Invasive species threaten global ecosystems, costing an estimated $1.4 trillion dollars each year. Two of the most insidious invaders are sister species of Indo-Pacific lionfish, Pterois volitans and P. miles, which were probably first released to the Atlantic Ocean near Florida, presumably through the aquarium trade. Since they can breed year-round and have no natural predators in the Atlantic, they’ve quickly colonized the North American coast up to Rhode Island, the South American coast down to Venezuela, and throughout the Gulf of Mexico and Caribbean.
Together, the severity of the lionfish invasion and the prevalence of CFP make for a thorny problem. That’s because the primary way through which the lionfish invasion is mitigated – or rather, the way in which we’re trying to limit it – is through targeted fishing. In some heavily infested places, like the Bahamas, organizations like the Reef Environmental Education Foundation (REEF) have sponsored “derbies,” which can haul in thousands of lionfish in a single day. In a related effort, REEF, along with NOAA, have begun to encourage people to eat lionfish. They published a lionfish cookbook, and tout the taste and nutritional benefits of the fish’s flesh. In one fell swoop, that turned fishermen into conservationists.
However, the concern that lionfish may contain ciguatera is getting in the way of lionfish cuisine. The Florida Sea Grant, together with the FDA, has said that the REEF/NOAA campaign is premature. A preliminary test, they say, indicated that lionfish can contain ciguatoxin. On the one hand, in five years of organized lionfish derbies, there have been no confirmed poisonings. Still, the FDA’s warning has raised concern, especially in places where CFP has been a serious problem, like the US Virgin Islands. And that concern is threatening to derail the important conservation efforts made by the lionfish fishery.
Christie Wilcox, a graduate student at the University of Hawaii, Manoa, and lionfish biologist Mark A. Hixon think that the appearance of ciguatoxin may be a case of mistaken identity. Lionfish, which are known as scorpaeniform fishes, are indeed known to be toxic, thanks to venoms that come from their fin spines. Those venoms are called, naturally, scorpaenitoxins. Could scorpaenitoxins mimic ciguatoxins, making the test for ciguatoxin result in false positives? Since the toxins are both colorless and odorless, they only way to test for their presence is through biochemical assays. Indeed, while the scorpaenitoxins are localized predominantly in the spines, Wilcox verified that they could be found throughout the lionfish’s body, including in the parts that are typically tested for ciguatoxin. It seems as if ciguatoxin tests could be contaminated by the presence of scorpaenitoxins.
Luckily, there is one key difference between the two families of toxins, and that’s what happens to them when heated. If lionfish meat gets cooked prior to testing, then the scorpaenitoxins would be de-natured, rendering them harmless and invisible to the assays. Ciguatoxins, on the other hand, do not denature due to cooking, and remain present and harmful in cooked lionfish. So while it is possible to mistake the two toxins in raw fish, it would be impossible to do so in a cooked sample. And that is what Wilcox recommends.
This study doesn’t necessarily mean that all lionfish are free of ciguatoxins, only that the ciguatoxin tests are not specific enough to rule out the confounding role that the naturally occurring scorpaenitoxins could play. Better testing protocols would be helpful. “Unfounded fears of ciguatera poisoning have the potential to cripple the fishery for lionfish permanently, even though the majority of lionfish may be perfectly safe to eat,” Wilcox says. And it’s not just the fishery that suffers; local economies can too. In French Polynesia, CFP costs more than $1 million each year in lost earnings due to banned fish. “In areas where ciguatera is common, lionfish should be treated with caution,” she said, just as you would for any other marine predator, like barracuda or grouper. “But in areas where ciguatera is rare or nonexistent, [like in] North Carolina, there’s no reason to fear lionfish more than any other fish,” she adds. In those places, it’s probably perfectly safe to fire up the barbecue. – Jason G. Goldman | 06 August 2014
Source: Wilcox C.L. (2014). False positive tests for ciguatera may derail efforts to control invasive lionfish, Environmental Biology of Fishes, DOI: http://dx.doi.org/10.1007/s10641-014-0313-0
Header image: Flying lionfish (Pterois volitans), shutterstock.com
Why lizards need elephants to surviveMay 22nd, 2015
The surprising shapes of mountain rangesMay 21st, 2015
A new form of chytrid fungus threatens US salamandersMay 20th, 2015
The monkey-flower has two facesMay 19th, 2015