How scientists aim to combat ‘Darwin’s nightmare’ — the invasive lionfish

The lionfish has always been a relentless predator. When it lived only in the Indo-Pacific, its ferocity and aggression were contained. But since the species has expanded to the Atlantic, its overpopulation is threatening fellow aquatic creatures. So scientists are developing a robot to hunt the predator, thinking that killing mass numbers of lionfish may be the only way to combat the problem.

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    Lionfish have voracious appetites that are upsetting coral reef ecosystems from Rhode Island to Venezuela.

    But a new nonprofit company has an unusual plan to restore balance to those environments before it's too late.

    In the latest edition of our online series "ScienceScope," science producer Nsikan Akpan has the scoop.


    The lionfish is an invasive species. It's also Darwin's nightmare.

    In its native home of the Indo-Pacific, the lionfish is a fierce, unrelenting predator. In the mid-1980s, exotic pets, including lionfish, became popular in the U.S. Scientists suspect pet owners eventually dumped their adult lionfish in the Atlantic.

    The lionfish now threatens ecosystems up and down the Atlantic. But they should watch out. A new robot is entering the fray. Meet the lionfish terminator.

    To learn about this robot, we traveled here to Bermuda, where we teamed up with the Nekton mission. This new alliance of 30 scientific organizations and companies wants to conduct one of the largest marine life surveys in history.

  • OLIVER STEEDS, Mission Director, Nekton:

    These divers are the first 1,900 meters. And then these extraordinary submersibles go down even further. We have adapted some with some of the latest filming and scientific equipment, so, we can sample, we can study, and we can research, as welcome as taking scientists down into those depths.


    Of the earth's oceans, only 5 percent have been explored. That means we know more about the moon than the water that covers 70 percent of the Earth.

    Nekton wants to fill the knowledge gap by making a baseline measurement of ocean health. That's because our are facing threats, including the spread of invasive species like the lionfish.

    Chris Flook is a collector of marine specimens for the Bermuda Aquarium Museum and Zoo. And he was one of the first to notice the region's lionfish invasion 16 years ago.

    CHRIS FLOOK, Bermuda Aquarium Museum and Zoo: But then very quickly, I started to notes that, over time, we were losing small fish from these areas where I traditionally went and found lots of small juvenile fish. And lionfish were becoming more and more common.

    So, by about 2007, we actually started a culling program in Bermuda to tackle these invasive species.


    Now known as the Bermuda Lionfish Task Force, the team holds daily dives and fishing tournaments to rid their waters of these invaders. Its members consist of recreational swimmers, professional divers and even local scientists like Dr. Gretchen Goodbody-Gringley.

    DR. GRETCHEN GOODBODY-GRINGLEY, Bermuda Institute of Ocean Sciences: The lionfish are a threat to the ecosystem because, first and foremost, they're voracious predators. So, they consume an exorbitant amount of food, more than any other potential predator out there right now.

    All of the white part is solidified fat, because it's unique to lionfish that they overconsume, to the point that they get fatty liver disease.


    This is because smaller fish in this region don't recognize the lionfish as a threat. They swim right up to it and get gobbled up.

    Basically, the lionfish just opens its mouth. It's a big dilemma, because the task force can tackle lionfish only in shallow water. But in Bermuda, Goodbody-Gringley has found most lionfish live 200 feet below the surface. That depth is largely inaccessible to the average sport diver. But that's not too deep for a robot.

    Goodbody-Gringley and Nekton have teamed with a new nonprofit called RISE, or Robots in the Service of the Environment, that is developing a lionfish-hunting robot.

    GEOFFREY GARDNER, Robots in the Service of the Environment: The leading candidate is based on an electrofishing techniques, where if you put the lionfish between two electrodes and apply an electric current, that current voltage kills the lionfish or stuns the lionfish.


    The device is in its development stage. And dive teams are testing how lionfish might react to a robot arm with two metal electrode plates.

    The lionfish have few predators in the Atlantic. As a result, they're not conditioned to flee anything. Notice here, when the probe approaches from behind, the lionfish stay still. Saltwater is highly conductive, so it should act almost like a straight wire between two electrodes. That should keep other nearby fish from being stunned.

    But is the mass killing of lionfish ethical? The lionfish is a pest, but it's also a living creature.

    We spoke with ocean ecologist James Morris.

  • JAMES MORRIS, Ocean Ecologist:

    We harvest fish all over the U.S. and the planet. So, I don't think there is really any ethical issues with, you know, utilizing the resource.

    But if we're looking for an ethical question, it's one around introducing non-native species and the impact that it has on the region and specifically the biodiversity.


    That's it for now.

    I'm Nsikan Akpan, and this is "ScienceScope" from the "PBS NewsHour."

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