Most folks know about the devastating invasion of Lionfish in the Caribbean and Atlantic, those pretty tropical fish native to the Pacific that have taken over coral reefs and other marine habitats throughout the region. Genetic evidence suggests these decorative tropicals were deliberately released in Florida for some years by aquarium-keepers starting in the mid 1980s and underwent a population explosion in the absence of natural predators. Like most destructive predatory invasives, Lionfish reproduce rapidly, spread easily, colonize any new habitat readily, are generalists in their choice of prey, and unattractive to native predators.
What’s the current situation, and is there any hope for the already beleagured coral reefs of the Caribbean?
As you might guess from my DK username I’m a scuba diver with a passion for the marine world and I’ve been watching the Lionfish scourge since they expanded into the Caribbean. Originally the Lionfish spread northward along the Atlantic coast carried by the warm Gulf Stream. Then in 2007 they were seen in Cuba, and a couple years later all across the Caribbean, expanding in area and numbers exponentially as they settled into coral reef ecosystems similar to their native western Pacific habitats.
I’ve been diving the Caribbean since the mid 1990s and according to my log books, did not see a Lionfish until 2010. That was near Roatan, an island offshore Honduras. I was seeing Lionfish on almost every dive that summer. According to the yearly observations map (at article), Lionfish were first reported outside Cuba in Belize in 2008 and Cozumel in 2009, both places I dived those years, but I didn’t see any; their numbers were still few. But evidently by the end of 2009 Lionfish had colonized most reef sites in the Caribbean and their population density had increased to the point where they were seen routinely. I’ve seen them at every Caribbean site I’ve dived since then.
It’s a very bad situation, and many reefs have been decimated. The reality is that Lionfish will never be eradicated, but with a persistent culling program implemented by experts, it’s possible to manage lionfish. The problem I’ve seen is a lack of knowledge, organization and consistent effort.
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The reason it’s so important to reduce lionfish numbers is because their predation wipes out much of the reef ecosystem. Just a few lionfish will consume as much as 80% of juvenile fish on a given reef, and they can eat prey half their body size. Besides the loss of much of the reef fish community, lionfish also destroy coral indirectly. On a healthy reef herbivorous fish (like damselfish, parrotfish, surgeonfish) keep algae growth in check; without the herbivores, algae buries and kills the corals. A heavily infested reef looks lifeless: few fish or colorful corals, and mounds of algae. With Lionfish lurking in the shadows.
More information about lionfish biology and ecology can be found here.
The most common fishing tool used is the Hawaiian sling, a simple spear propelled by a rubber band/tubing (although I’ve heard of divers using a Glock!). The dive guides we accompanied in Roatan in 2010 and 2011, and in Belize in 2013 and 2014, carried a spear on some of the dives and hunted as we swam along. They make it look easy but it really requires a lot of skill. Davide in Roatan and Cardinal and James in Belize would spear a Lionfish, and either knock it against a coral knob or use a knife to kill it. Three options then: drop the Lionfish, put it on a string to bring back, or feed the Lionfish to a nearby predator.
Here’s James at Turneffe Atoll cleaning the lionfish he collected on a recent dive (these are just the ones big enough to save, he left most back on the reef after killing them). James has been stung enough times to be extremely careful now, since the effect amplifies with every exposure.
For years, the hope was that by feeding Lionfish to groupers, Moray eels or Reef sharks (or lobsters, toadfish, etc) these predators would learn how to hunt Lionfish on their own, and control their population as these reef predators do in the western Pacific. It’s pretty exciting to watch a big fish or eel dart in, snatch a lionfish off a spear, and swim away gulping it down. I watched that many times. However, things went sideways on this plan. The predators did not learn to catch lionfish, but they did learn that human divers, especially those carrying spears, are a fruitful source of food. Green Moray eels are ordinarily very shy creatures, hiding in crevices, difficult to see. By 2013 the Morays were boldly cruising out in the open. One time a 6-foot moray lunged at me, even though I had no spear. It was very unnerving! Wild animals do not attack divers….unless they’ve been provoked. Teaching them to attack fish on spears is a provocation. It’s become actually dangerous to go out spearfishing now in the Caribbean.
This short video shows abnormal Green Moray behavior at Grand Cayman (an example with sharks can be seen here), and why:
In recent years, savvy Lionfish hunters have devised tools and strategies that are safer and more effective. For the past two years I’ve been diving at Little Cayman Island, a speck of coral limestone between Grand Cayman and Cuba. The three dive operators on the island set up a regular volunteer culling program in 2009 when lionfish first appeared there, eggs having floated in with sargassum weed, and go out every single Wednesday evening to spear all the Lionfish they see. According to Gay, who runs the dive op where we stay, at first they were collecting hundreds every week, amounting to about 5000 a year. Now she says they are lucky to find 3-15 per week, and the Lionfish are much more elusive. They cull at dusk, when the Lionfish come out to feed. Visitors like us are not allowed to come along on these dives because there is a very real risk of shark attack.
Early containers for collecting lionfish were net bags, and then plastic bags to avoid getting stung. But both these are too easy for large predators to attack, so they started using hard buckets. There are now commercial containers, and the Little Cayman folks prefer to use the opaque ones. Otherwise sharks and eels can see the lionfish through the container and will go after it. Gay described occasional encounters with sharks in which she’s had to bop them on the nose to discourage them. One day the dive guides brought the hunting gear along on one of our dives because lionfish had been seen at a particular location. Here is the gear they use:
A video shows how hunting works these days among serious lionfish cullers.
Lionfish can live down to 1000 feet, and recreational divers are discouraged from going deeper than 100 feet, so it’s inevitable more fish will reoccupy the shallower reef. That’s why constant culling is necessary. But the 8-year program at Little Cayman proves it’s possible to manage their numbers, if divers hunt them down as relentlessly as the lionfish do their prey. During the two weeks in April I dived at various sections of reef around the island I saw 3 Lionfish total. That’s a fraction of the populations in Belize and Roatan (where I saw several per hour), and negligible compared to the heavily infested reefs of Florida, the Bahamas and elsewhere.
Lionfish are extremely venomous to touch, which is the reason they lurk quietly rather than swim quickly away when you approach. Mike showed us which spines are most dangerous.
In Indonesia and New Guinea I saw lionfish in their native habitat, where they are preyed on by groupers especially, so their numbers are few. Up until a few years ago there was no sign the Caribbean groupers, or any other local fish, were figuring out how to catch and eat lionfish on their own, in spite of the many many fish they were fed from spears. However, the dive guides this year said they had seen groupers actively catching lionfish! And I’ve been reading reports of this happening elsewhere (such as Aruba). There is some reason to hope this new food source will be exploited by native fish. In the meantime, the only real hope for keeping their population low enough to avoid disaster on the reefs is organized, persistent, skilled culling programs like the one at Little Cayman.
Coral reef ecosystems are under attack by many human-caused dangers. The least we can do is put serious effort into manageable threats like this invasive species. If we give up, it is certain there will be no living coral reefs in the future.
That’s more of my nature news from the Caribbean.
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