Latest weapon against lionfish invasion? Meet the Roomba of the sea.

If you can’t beat them, eat them. That is the common wisdom of many scientists, conservationists, and fishermen who dream of ridding the western Atlantic of invasive lionfish, a stunning aquarium fish that, when introduced in the wild, dominates and destroys reef ecosystems. However, catching lionfish has never been simple; they are not easily targeted by line or net fishing. Now, a surprising new invention may bring lionfish hunting to the masses and help clear the seas of this invader: a submersible robot.

With its striking stripes, diaphanous fins, and mane of colorful but poisonous spines, the exotic Indo-Pacific lionfish makes for a popular aquarium fish. But when released into the Atlantic in the 1980s (presumably by aquarium aficionados who tired of the voracious pet), the fish thrived and became a menace to native fish species and the reefs they rely upon. Lionfish populations first exploded off Florida’s coast; now, lionfish have expanded their range throughout the Bahamas and the Caribbean all the way down to South America. 

“A number of characteristics make the lionfish the perfect invader,” says Stephen Gittings, a coral reef ecologist and NOAA’s chief scientist for the National Marine Sanctuary System. “They can eat fish up to half their body size and a single lionfish can eat dozens of fish in a day. Since no native species prey on lionfish, you’re not losing very many of them over the course of time so they just dominate and take over.”   

What’s more, a single female lionfish can lay up to 2 million eggs a year, which are impervious to predation since they are housed in an inedible sac. Once lionfish are established in an area it is very difficult to get rid of them and they can quickly destroy much of a reef’s biodiversity. Lionfish can strip a reef of 90% of its juvenile fish species in as little as five weeks.

Reef Roomba to the rescue  

Colin Angle, the co-founder of iRobot, which produces the automated vacuum known as the Roomba, is an avid diver. When diving in the Bahamas a few years ago, Mr. Angle spotted a beautiful fish wreathed in a mane of colorful spines. He took pictures of the fish, which he showed the dive boat’s captain. The captain took one look at the photo and spit over the side of the boat in a show of disgust. It was, of course, a lionfish. 

Determined to use his access to technology to tackle the lionfish problem, Mr. Angle directed his nonprofit, Robots in Service of the Environment (RSE), to develop a submersible robot that could descend to great depths to gather lionfish. From this, the Guardian was born.  

The Guardian is a 20-pound submersible remotely operated vehicle equipped with cameras and lights – and two paddles that can deliver a 20-volt shock to a lionfish. In a boat above, a human driver with a laptop guides the Guardian toward lionfish, and can push a button that activates the paddles to stun the fish. Once stunned, they are vacuumed into a water-filled storage chamber that can hold up to 20 fish. When the chamber is filled, the Guardian returns to the surface with its catch. 

“We’re providing the low-cost scalable robot that can hunt and capture lionfish and effectively bring the ability to hunt lionfish to anyone,” says Adam Cantor, director of engineering at RSE. “We provide the hardware and software needed to capture these fish to local everyday fishermen and tourists at a reasonable cost. People can have some fun and at the same time protect the reef.”

Lionfish. It’s what’s for dinner.  

Lionfish aren’t just pretty – they happen to make a tasty and nutritious meal. A spearfishing diver can bag a dozen or more lionfish in a day and sell the catch to local restaurants or retailers such as Whole Foods. Many coastal communities now hold derbies that pull in thousands of lionfish over the course of a few days.

“The issue is that lionfish can be found all the way down to a thousand feet and they breed between 200 and 400 feet deep and aggregate there. There’s no diving you can do to reach that depth,” says Mr. Cantor. “So that’s where we come in. As you go deeper, it’s much more cost-effective to use the robot. Also, by catching lionfish where they are breeding and hibernating you make sure that they never make it to the shallow reefs and therefore can’t devastate those native populations.”  

The Guardian is currently priced at $1,000, and RSE plans to put it on the market next year. Lionfish sell for over $5 a pound and a single machine can catch up to 20 fish per dive. 

“I think absolutely there’s a market for it. There’s a ton of lionfish down deeper that we can’t get to,” says Andy Lowe, a professional diver and lionfish hunter. “The thousand-dollar price point is very good, but for me to personally consider buying one I’ll need to see it get a lionfish off a reef at depth. If it can do that it’s got great potential.”

How many people purchase the Guardian to hunt lionfish remains to be seen, and without consumer buy-in, the impact of the Guardian will be limited. RSE plans to expand the scope of the Guardian’s work to include other underwater jobs like inspecting pipelines and the hulls of ships or conducting underwater surveys. It views the Guardian as the first of many future projects.

“In the background, we are looking at other environmental issues that robots could help resolve,” says Andrew Doucette, communications lead at RSE. “There are several invasive species around the world that we think robots could help with like pythons in Florida or the urchins in California but we might not always be underwater. We could end up doing something in the Sahara Desert, I don’t know.”