The ‘Roomba of the sea’ hoovering up invasive lionfish

A new autonomous submersible device from the mind behind the Roomba could do to invasive lionfish what its predecessor does to dirty floors – get rid of them. If successful it could be a major environmental boost to Caribbean coral reefs.

Guardian underwater
RSE’s Guardian is made by the creator of the Roomba and works in a remarkably similar way

In the last couple of decades an invasion of non-native lionfish in the Caribbean has developed into one of the biggest ecological crises the region has ever seen. Capable of eating almost everything in sight, reproducing at an alarming rate and with no natural predators of their own, these invasive species have become an unstoppable cancer for coral reefs. But an unlikely new solution of the vacuum variety could be about to help remove the invaders from their new territories forever. The breakthrough comes from Robots in Service of the Environment (RSE), founded by the creator of the famous Roomba autonomous hoover. Inspired by its domestic equivalent the new underwater vacuum known as the ‘Guardian’ is capable of catching 20 lionfish at once, and may be our best bet at tackling the lionfish problem before it is too late.

The lionfish invasion

Unlike most other wildlife invasions the lionfish invasion in the Caribbean is actually quite unique due to the fact there is not one but two different non-native species at play. Both species, Pterosis volitans and Pterosis miles, originate in the Indo-Pacific region and are closely related to one another. They were first spotted off the coast of Florida in 1985 and it is believed they ended up there as result of the private aquarium trade. That is to say that locals who collect reef fish and keep them in their own tanks, were unequipped to handle the lionfish (you will soon see why) and so ended up releasing them in the ocean instead. It is believed it would only have taken a few dozen to be released to cause the invasion and explains why both species migrated together.

distribution-map.jpg
The lionfish invasion is one of the largest wildlife invasions ever, under the sea or on land

At first there was very little indication that the lionfish would be a problem and because there were so few at the time, scientists were unsure if they were even there at all. But like lots of invasive species there was a time lag before a population increase and it wasn’t until the turn of the millennium until lionfish really kicked into gear. When it came the population explosion was unexpected, fast and geographically expansive. In 2000 sightings along the East coast of America skyrocketed and by 2004 the first lionfish reached the Caribbean in the Bahamas. In the following decade they spread to every country in the region and many experts now believe there is probably at least one lionfish on every Caribbean reef. This incredible distribution makes them one of, if not the most, widespread invasive marine species in history. In 2015 the first sightings of lionfish were made as far south as Brazil and there is no telling where it will end.

A veracious visitor

So just how have a handful of lionfish released from aquarium tanks managed to spread so far in such a short space of time? First of all they eat almost everything in sight. In the Caribbean they are known to feed on over 40 species of reef fish. But it’s not just what they eat that is the problem, it’s how much. All of the native fish suffer from the fact they seem unable to identify lionfish as predators. This is either due to their markings or the fact they are just an unkown quantity, but it means a lionfish can just swim up to a reef fish and swallow them in one go without skipping a beat. Their incredible stomachs are also capable of expanding in size by a factor of 30 meaning just one lionfish has the capacity to strip a small reef of fish in a couple of days.

Lionfish upclose
Invasive lionfish are ruthlessly efficient and capable of spreading across an area rapidly

As well as being top predators they also benefit from the fact that no predators seem to want to eat them at all. This is probably also due to the fact they are being misidentified by native species, and it means they do not have to worry about defensive or evasive behaviours. Those brave predators that might fancy a nibble also fall victim to the very toxic spines that line the lionfish’s body. The lionfish even appear to be immune to all the marine parasites and diseases in the area. But the final secret to their success is their reproductive capacity. Female lionfish are capable of producing eggs every 4 days meaning they can produce an incredible 2 million eggs a year. Of course not all of these will develop into fully fledged lionfish, but it is the reason behind their exponential increase in numbers and geographical range. Many researchers also suspect there is now hybridization between P. volitans and P. miles meaning it is much easier for them to spread.

Hard to remove

The impact of lionfish across the Caribbean has been devastating for the environment and local people. The massive reduction in reef fish has meant a loss of food security for many communities and barren dying coral reefs are becoming less desirable to visit. As a result removing lionfish from the Caribbean is a top priority for conservationists and governments. One of the big ways this has been attempted is through spear fishing. It is strongly encouraged that all divers in the region now carry spear guns and shoot lionfish on sight. When properly prepared lionfish is also a tasty, healthy and abundant food source for local people. But the big problem is that lionfish are capable of retreating to the depths as far as 1000 feet down, out of range for spearfishing. This means even if they are removed from a reef it is never a permanent solution and they always come back.

Spearfishing
Spearfishing lionfish by hand is currently the only way to remove them from coral reefs, but it isn’t enough

Hoovering up the mess

To combat this problem Robots in Service of the Environment (RSE) have developed a new autonomous submersible robot capable of diving down to the deep to hoover up the lionfish invaders. RSE was created by Collin Angle, the co-founder of the iRobot company who is also a keen scuba diver. He was behind the famous Roomba vacuum that travels around your house unassisted cleaning the floor as it goes. In many ways RSE’s new device the ‘Guardian’, first released in 2017, actually works in a very similar way. Only instead of hoovering floors it goes around the ocean looking for and sucking up lionfish. It essentially looks like a big glass tube with the added capacity to move around the deep ocean.

Guardian
The guardian on full display out of the water

The Guardian is tethered to the surface and using an on-board camera system and photo identification software it can be used to pinpoint lionfish with incredible accuracy. Two specialised stunning paddles then make contact and immobilise the lionfish which are then humanely hoovered up into the holding chamber. It can hold up to 20 lionfish at once, meaning the Guardian can clear out large areas in a single dive. Because it can reach so deep it is also much more effective than spearfishing and can even target lionfish at the critical depth where they breed at around 200-500 feet. Its eight thrusters also give it six planes of movement and allows for complex hunting manoeuvres and stabilization in strong ocean currents. You can check it out in action for yourself in the video below.

Will it work?

The lionfish invasion is a problem that is unfortunately unlikely to ever be completely solved by a single solution. However at the same time RSE’s Guardian has the potential to be the most important counter-measure against lionfish yet, and as a result has made tackling the problem seem a lot more achievable. But one of the big stumbling blocks for projects like this is scale and affordability. If it costs ridiculous amounts of money to create the robots and you needs lots of them to cover a wide area, then no matter how effective it is, it is unlikely to ever become feasible.

Single catch.jpg
Regardless of how successful the Guardian is, it is still better than hunting lionfish one at a time

But this is where RSE is bucking the trend by making the robots as cheap as possible whilst remaining effective at what they do. The end goal is to be able to produce a single unit for as little as $1000. Not only does this make the idea affordable, it could actually make it profitable. That is because with the increase in appetite for lionfish in the Caribbean captured lionfish can be sold for up to $5 per pound there. With a capacity to hold up to 30lbs in weight you only need to fill it 7 times to start making a profit. This give the Guardian a big advantage because as most conservationists will tell you the success of projects like these relies all too much on money. Only time will tell if RSE can help rid the Caribbean of their foreign invaders, but in my opinion they might be the only ones who can.


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