This fish-zapping robot is hunting invasive lionfish in coral reefs

On a recent afternoon in February, a group of engineers sat in a boat in the Bahamas with a laptop and a game controller, driving a small robot as far as 200 feet below the surface of the water. The goal: to capture lionfish, an invasive species that is threatening local marine life.

The robot is the newest iteration of the Guardian, a machine developed by Colin Angle, the inventor of the Roomba. He developed the machine after he heard about the destruction the venomous fish was creating in local ecosystems. The species, which is native to the Indo-Pacific, has no native predators in the Atlantic. “Here, there is nothing stopping them,” says Adam Cantor, director of engineering for RSE, or Robots in Service of the Environment, the nonprofit that Angle launched to work on the project. “Local fish don’t see them as a threat and often swim close to them and are just readily gobbled up. No predator is willing to eat them, nothing is immune to their venom, and in the Atlantic, they are eating anything up to half their size.” In the Bahamas alone, the lionfish will eat 72 different species, far more than any other local predator; a single lionfish in a coral reef can reduce native reef fish by 79%.

Some restaurants and grocery stores now carry the fish in an attempt to encourage fishing. But the fish doesn’t respond to bait and is difficult to catch with a net. The robot, which stuns the fish with electricity before sucking it into a tube, is an alternative. The old version, which got power through a tether, couldn’t swim deep underwater. Now it can go deeper than divers can safely swim to the depths where the lionfish breed, between 200 and 500 feet below the surface. The new version also holds more fish. “Now that we’re going deeper, you definitely want to catch more fish before the robot needs to return to the boat,” says Cantor. It also solves some usability challenges–now, for example, the robot has a handle, and the last version didn’t–a problem when you have a robot full of venomous fish and no easy way to pick it up.

Right now, the robot has to be controlled by a human to ensure that it only catches lionfish, and not similar-looking fish such as a wolffish. (Eventually, however, it should be capable of identifying lionfish on its own.) By bringing the robot to particular coral reefs where there may be hundreds of lionfish, fisherman can help protect the area. “The expectation is that even a few robots in key locations can protect the reefs around them,” says Cantor. The company has not yet announced when the robots will be on the market, but the team plans to travel back to the Bahamas at the end of the month to continue testing and catching fish. “The water is already warm and the lionfish are plentiful,” he says. “So we’re fighting the good fight down there.”