In this episode, a NOAA ecologist discusses how invasive lionfish have become established across the Southeast U.S. and Caribbean. How did the fish get to the Atlantic? While the exact cause is unknown, it's likely that humans provided a helping hand. While NOAA researchers have concluded that invasive lionfish populations will continue to grow and cannot be eliminated using conventional methods, efforts continue to control populations.
HOST: This is the NOAA Ocean Podcast. I’m Troy Kitch. In this episode, we’re going to listen in on an interview from a few years back between host Kate Nielsen and NOAA scientist James Morris. James is an ecologist with the National Centers for Coastal Ocean Science. The topic: invasive lionfish. In about fifteen years or so, lionfish have become widely established across the Southeast U.S. and Caribbean. The problem is, these venomous, fearsome looking fish aren’t supposed to be there. Recent estimates of lionfish densities indicate that these non-native fish have surpassed some native species in U.S. waters — in some locations there are hundreds of lionfish per acre.
Before we begin, some background. There’s actually two species of lionfish that have been introduced into the Atlantic, the red lionfish and the devil firefish. The red lionfish is from the Pacific Ocean and it’s distributed as far as Australia and the pacific islands. The devil firefish is from the Red Sea and Indian Ocean region.
So how did these fish get to the Atlantic? The exact cause is unknown. While no one actually observed someone releasing lionfish into the Atlantic, there are clues that suggest how it happened. James Morris and Kate Nielsen pick up the conversation here:
JAMES MORRIS: One clue is that lionfish were heavily imported in the past into the U.S. They are a very popular marine ornamental species, people like to hold them in their aquarium and have them as pets. They’re very beautiful, very ornate fish. They’re kind of exotic because they are a scorpion fish, they are venomous, and just by virtue of their presence and their volume being imported to the U.S., we suspect that they were probably released from the aquarium trade.
HOST: So, what can we do, what can humans do, to help with this lionfish invasion?
JAMES MORRIS: Well, the first thing we can do is stop releasing non-native species. We’ve got to work harder and do a better job of informing the public about the impacts of invasive species. In terms of lionfish and what we can do specifically about this invasion is we’ve been working hard over the years to educate the public about the problem of lionfish and more importantly the possibility that we could control lionfish in certain locations. We don’t believe, for a moment, that we can eradicate lionfish. We just don’t have the technology, even if we wanted to go out and remove all the lionfish out there, we wouldn’t really know where to go look for them all. We just don’t have that good of habitat maps, especially in the southeast U.S. And it’s just the expanse. Lionfish inhabit out to 1,000 feet and up to less than a foot of depth in some locations and so their habitat is very broad and wide.
We are looking at control plans for certain locations. We’ve been working with the National Park Service, National Park Service has done a wonderful job of developing a national lionfish response plan, working on control plans within National Park Service areas impacted by lionfish. We believe that we can make a difference in certain locations. Locations that are small, have boundaries, that have the infrastructure to control their local densities for conservation mandate. And we believe that we can work to control them in national marine sanctuaries in similar ways that we can in our national parks. But that requires programs and that requires that we can organize in how we can do this.
We have found that harvesting lionfish as a food fish is a potential way that you can encourage removals and provide long-term incentives for removals. Now, there’s a bit of controversy around that because we don’t want folks to, because of having a positive experience being able to harvest lionfish, to think that might make it a good idea to produce other non-native species because you could fish them as hard as you want to and that’s a bad idea because there are unintentional consequences of those kind of things. But we do know that really harvesting them as a food fish really is the best thing that we have on the table in terms of creating a long-term incentive for removal.
HOST: And that’s even given their venom defense, we’re talking about harvesting as a food source. So it is safe to eat and handle lionfish?
JAMES MORRIS: It is. It’s safe if you handle it properly. We need to be clear in that there’s a difference between a venomous fish and a poisonous fish. Poisonous fish is a fish that essentially has a toxin or poison in its flesh, that you will get sick from eating it. A venomous fish is a fish that has a venom somewhere in its body, it’s usually not in the flesh, that would be poisonous, but along the spines or in the teeth or some type of bony structures of the fish. In the case of lionfish, the venom is located only in the spines of the fish, it has dorsal, pelvic, and anal spines. The venom glands are located along grooves of the spine. There is no venomous sac at the base of the spine as is commonly said. That venom gland actually goes along the grooves of the spine. If those spines are removed before cleaning the fish, then there’s no risk there. There are field guides. There are lots of instructions now that are available to help people learn how to clean the fish.
HOST: And there is lots more to this interview between Kate and James. Check our show notes for link to the longer podcast. While researchers continue to explore ways to reduce the populations of lionfish in U.S. waters, the lionfish is only one of many invasive species found across the nation. It’s a big problem. Invasive species can lead to the extinction of native plants and animals, destroy biodiversity, and permanently alter habitats. These invaders can be introduced to an area in many ways: by ship ballast water, accidental release, and most often, by people like you and me. In the case of lionfish, they were likely introduced into waterways by people with aquariums. So the best thing we can do is to help spread the word about the damage that non-native species can do — and the problems that can result from releasing non-native species into the wild. And that’s all for this episode of the NOAA Ocean Podcast. Until next month.
Since lionfish are not native to Atlantic waters, they have very few predators. They are carnivores that feed on small crustaceans and fish, including the young of important commercial fish species such as snapper and grouper. How lionfish will affect native fish populations and commercial fishing industries has yet to be determined. What is known is that non-native species can dramatically affect native ecosystems and local fishing economies.