The Worst Marine Invasion Ever

The state of the universe.
July 1 2013 7:00 AM

The Worst Marine Invasion Ever

I could not believe what I found inside a lionfish.

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In 2010 scientists named the lionfish invasion one of the top 15 threats to global biodiversity. In the three years since, the invasion has only worsened. The only solution is to fight fire with fire, or in this case, pit our bottomless stomachs against theirs. We really do have to eat them to beat them.

Unfortunately, developing a fishery for lionfish isn’t as straightforward as it sounds. They don’t tend to bite hooks and live in complex habitats like reefs and wrecks that can’t be fished with large nets. To catch them, people have to get in the water and spear them one by one—an expensive and tedious way to fish. For lionfish fisheries to turn a profit, demand will have to be high and constant. So far, only a handful of local restaurants have taken the bait, enticing locavores with a truly sustainable menu option. Their business alone isn’t enough, though, to really drive a market.

That’s even assuming that lionfish are completely safe to eat. Recently, the Food and Drug Administration raised flags about lionfish—but not because of their venom. They are concerned that lionfish may contain ciguatoxin, a common tropical poison that causes somewhere between 50,000 and 500,000 cases of ciguatera fish poisoning every year. Ciguatera isn’t unique to lionfish; the disease occurs in tropical waters worldwide. The small lipid ciguatoxins that cause it are made by dinoflagellates, microscopic algaelike animals that live on and near reefs. Animals don’t really break down ciguatoxin, so it bioaccumulates up the food chain, thus large predators that eat high on the food web are most likely to have dangerous levels of ciguatoxin. In areas where the disease is endemic, species such as groupers and barracuda are simply too risky to consume and are often avoided by fishermen. The FDA is concerned that lionfish should also be included on that list, meaning that in areas such as the Virgin Islands, lionfish would be permanently off the menu. Their press release stated that more than a quarter of lionfish sampled contained unsafe ciguatoxin levels, and it issued a warning against eating them.

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To other scientists, including myself, the news is baffling. I haven’t seen the actual data (because the FDA has yet to release them), but such high numbers just seem unbelievable. Thousands of lionfish are eaten every year after tournaments, and there hasn’t been a single case of ciguatera from a lionfish. If so many are dangerous, why hasn’t anyone gotten sick? And even if some areas do have ciguatoxic lionfish, surely other areas are safe. After all, we can still eat grouper and other predators from much of the Atlantic and Caribbean. Lionfish shouldn’t be more ciguatoxic than other reef fish—not unless their diet is very, very different.

One of the tough things about ciguatoxin is that we don’t have reliable, direct tests for it. There is a diverse set of indirect assays, all with different methods, different detection levels, and different specificities. All of this makes it hard to compare studies done by different labs and hard to ensure accuracy. Top that off with a species that has never been tested for ciguatoxin before, and things get really messy. This is where my research comes in.

Lionfish possess potent venom that activates sodium channels on the surface of nerve cells, causing a massive influx of calcium. This leads to the release and depletion of the neurotransmitter acetylcholine. This happens to be the exact same thing ciguatoxin does. Which, to me, raises a very important question: What if lionfish venom is getting into ciguatoxin assays? Are venom compounds causing false positives? The venom itself, though excruciating in the form of a sting, is harmless on the plate. Unlike ciguatoxin, it’s readily degraded by heat, so if it is venom and not ciguatoxin causing positive tests, lionfish may be safer to eat than the FDA data suggest. Hopefully, the samples I collected on this trip to North Carolina—where ciguatoxin isn’t an issue—will provide some answers.

James Morris pulling a lionfish's stomach for gut content analyses.
James Morris pulling a lionfish's stomach for gut content analyses

Courtesy of NOAA

Until we know more, though, promoting fisheries is a potentially dangerous management strategy, at least in certain areas. Some governments have stepped in to promote hunting even without a formal fishery plan, in an attempt to protect their reefs’ future. But many of the small, developing countries in the Caribbean simply don’t have the resources to fund large-scale lionfish removal efforts. For them, steady fisheries would be the only way to get fishermen to catch lionfish instead of currently lucrative species such as grouper.

While we wait to see whether we can drum up the demand, the lionfish are making themselves comfortable. They’re embedding themselves in already fragile ecosystems, restructuring food webs, and pushing reefs toward irreversible ecological cascades. They’re exploring new habitats, discovering the rich resources provided by seagrass meadows and mangroves, even travelling miles inland and upstream in Florida. They’re taking over reefs, wrecks, and rocky territory from the surface to more than 800 feet deep, and they’re gorging themselves on whatever young fish happen to live there. They are, quite literally, growing fat off of our inaction.

That’s not to say there is no hope. Yes, we’re going to have to learn to live with the lionfish. We’re going to have to accept their presence in the Atlantic, Caribbean, and Gulf of Mexico, but we can use science to arm us against this invasion. In the quiet lab in North Carolina, Morris isn’t just studying fish. He’s preparing us for battle. In this endless war with a formidable foe, knowledge truly is power. The power to predict. The power to pre-empt. The power to fight back and save the species we value most. The power to educate and rally reinforcements to drive back invaders. The more we know about the lionfish, the better our strategies will be to deal with them and future invaders and the better our chances of success. The lionfish caught us by surprise, but Morris isn’t going to let them stay one step ahead. Even if we can’t eradicate these gluttonous fish, we may be able to manage them and minimize the damage they do to our precious marine ecosystems.

Considering it’s our fault that lionfish are here in the first place, it’s really a war against ourselves: against our bad habits, against our casual disregard for the ecosystems that protect and sustain us, against the attitudes and mindsets that led to such a devastating invasion to begin with. It’s a war that, as a nation, as a species, we cannot afford to lose. And one thing is for certain: With so much at stake, it’s going to be a bloody one.

Christie Wilcox is the author of Discover magazine's Science Sushi blog and a Ph.D. candidate in the cell and molecular biology department at the University of Hawaii, where she studies the protein toxins in venomous fish. Check out her website or follow her on TwitterGoogle+, or Facebook