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Alex  Mustard/NaturePL.com

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Lionfish Invasion

Experts team up to protect coastal waters from a fearsome fish

With its bold stripes and spiny fins, the lionfish is a stunning sight. But in the waters along the east coast of the U.S., lionfish aren’t appreciated for their beauty. They’re doing major damage to living things in that area, and just about everyone wants them gone!

Lionfish have bold stripes and spiny fins. They are striking to look at. But lionfish aren’t viewed as beautiful along the east coast of the U.S. They’re doing major harm to living things in that area. Just about everyone wants them gone!

Fabien Michenet/Biosphoto

Lionfish spread their fins wide to corner their prey before swallowing it whole.

Lionfish are typically found in the South Pacific and Indian oceans. So how did they end up halfway around the world? Lionfish have long been popular pet fish. Experts think a few pet owners dumped lionfish into the Atlantic Ocean in the 1980s. Over time, the fish multiplied and spread to new areas. Today, they are an invasive species, wiping out fish populations up and down the Atlantic coast. 

Experts are working to rid the water of these fishy invaders. They are coming up with creative ways to kill the fish, from hunting them with spears to stalking them with robots. 

Lionfish usually live in the South Pacific and Indian oceans. So how did they end up halfway around the world? The fish have long been a popular pet. Experts think a few pet owners dumped lionfish into the Atlantic Ocean. That happened back in the 1980s. The number of fish grew over the years. They spread to new areas. Today, they are an invasive species. They’re wiping out local fish along the Atlantic coast. 

Experts are working to rid the water of lionfish. They’re coming up with creative ways to kill the animals. That includes hunting them with spears and catching them with robots. 

Unwelcome Guests

The ocean off the coast of Florida is home to miles of coral reefs. These colorful underwater structures are made up of thousands of tiny animals called coral polyps. The polyps build skeletons that serve as homes for all kinds of plants and animals. 

Lionfish have wreaked havoc on these coral reef ecosystems. The fish have many traits that make them an effective invasive species, says ecologist Michelle Johnston. For one, lionfish have enormous appetites. They gobble up almost any small fish they find, and they keep hunting when their stomachs are full. Just 100 lionfish can eat 5 million native fish in a year.

Miles of coral reefs lie off the coast of Florida. Reefs are colorful underwater structures. They’re made up of thousands of tiny animals called coral polyps. The polyps build skeletons around themselves. The hard surface provides homes for many plants and animals. 

Lionfish are destroying coral reef ecosystems. The fish are a dangerous invasive species, says Michelle Johnston. She’s an ecologist. The fish have big appetites. They eat almost any small fish they find. And lionfish keep hunting even when they’re full. Just 100 lionfish can eat 5 million native fish in a year.

The loss of native fish can do enormous harm to coral reefs (see Reef Invaders). For instance, some native fish graze on tiny plant-like organisms called algae that grow on the corals. Without grazing fish, the algae grow out of control. Algae block the sun from reaching the corals, which can kill them.

Lionfish can live almost anywhere, and they reproduce rapidly. One female can lay 2 million eggs a year! Plus, most predators aren’t interested in eating lionfish. The fish are covered in spines that shoot painful venom. So far, that’s led top predators in the Atlantic, like barracuda, to steer clear. 

The loss of native fish can harm coral reefs (see Reef Invaders). Some native fish graze algae. These plant-like creatures grow on corals. The algae grow out of control without grazing fish. Algae block the sun from reaching corals. That can kill them. 

Lionfish can live almost anywhere. And their numbers grow rapidly. One female can lay 2 million eggs a year! Plus, most predators don’t want to eat lionfish. Spines cover the fish. The spines shoot painful venom. That’s why top predators in the Atlantic have so far stayed away. 

Fighting Back

In recent years, coastal communities have been fighting back against lionfish. Dozens of places now hold annual lionfish hunting events. Teams of divers armed with spears compete to catch the most fish. The events remove thousands of fish from local waters in just a few days.

But lionfish can hide deep in the ocean where divers can’t go. So engineers with a group called Robots in Service of the Environment are working on another solution: a lionfish-hunting robot called Guardian LF1.

People living on the Atlantic coast are now fighting back. Dozens of places hold annual lionfish hunting events. Teams of divers come armed with spears. They compete to catch the most fish. The events remove thousands of fish from local waters in just a few days.

But lionfish can hide deep in the ocean—too deep for divers to reach. So engineers came up with an idea. They work for Robots in Service of the Environment. They built a robot that hunts lionfish. It’s called Guardian LF1.

The robot is operated by a person on a boat. To nab a lionfish, the operator presses a button that stuns the fish with an electric shock. Another button triggers a vacuum that sucks the fish into the robot’s main chamber. “It’s like playing a video game,” says Adam Cantor, an engineer who helped design the robot.

During the robot’s first test in open water, it snagged a lionfish in a few minutes. Engineers are now working to improve the device. The latest version can hold 15 lionfish at a time.

A person on a boat controls the robot. He or she presses a button that creates an electric shock. That stuns the lionfish. Another button turns on a vacuum that sucks up the fish. The fish ends up inside the robot. “It’s like playing a video game,” says Adam Cantor. He’s an engineer who helped design the robot.

A team tested the robot in the open water. It caught a lionfish in a few minutes! Engineers are now trying to improve the device. The latest version can hold 15 lionfish at a time.

Christa Cameron/REUTERS (Caught Lionfish); Sue Daly/NaturePL.com (Prepared Lionfish)

Fishers sell the lionfish to restaurants that have them on the menu.

Eating the Enemy

Fishers could soon use the robots to catch lionfish more quickly. They could sell the fish to restaurants that serve them. Though lionfish produce venom, their flesh is edible. “Lionfish are delicious,” says Johnston. 

Still, experts say it’s unlikely that human efforts will eradicate lionfish from the Atlantic. Cantor estimates that it would take about 1,000 Guardian robots to put a dent in the lionfish population. 

That’s why Johnston hopes that sharks and other native predators will someday develop a taste for lionfish. That would go a long way to reducing their numbers. “We have to give it some time,” she says.

Fishers could soon use the robots to catch lionfish more quickly. They could sell the fish to restaurants. Even though lionfish make venom, people can eat their flesh. “Lionfish are delicious,” says Johnston.

Still, it’s unlikely people will wipe out lionfish from the Atlantic. Cantor thinks it would take about 1,000 Guardian robots to put a dent in the lionfish population.

Johnston hopes sharks and other local predators will help. They might develop a taste for lionfish. That would go a long way to reducing their numbers. “We have to give it some time,” she says.

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