New ROBOFISH could protect REAL fish from invasive species

By Tom Campbell via SWNS

A robotic fish could protect real ones from invasive species by scaring them off until they are too tired to reproduce, suggests a new study.

The device could seal the fate of mosquitofish - an unwanted species which chews off the tails of other fish and tadpoles - leaving them to perish, say scientists.

Invasive species are animals or plants from another region of the world, which are introduced to a new environment, often with the help of humans.

These 'nuisance species' can cause extensive damage to native ones and strain natural resources.

It's estimated that there are around 50,000 non-native species in the United States today. Of that 50,000, approximately 4,300 are considered invasive species

Now, researchers have come with a solution to tackle one of the world's most invasive species.

Lead author Dr. Giovanni Polverino at the University of Western Australia said: "Mosquitofish is one of the 100 world’s worst invasive species, and current methods to eradicate it are too expensive and time-consuming to effectively contrast its spread.

"This global pest is a serious threat to many aquatic animals."

The researchers' design was inspired by the mosquitofish's natural predator - the largemouth bass.

It mimics the appearance and movements of the invasive species' real predator, striking fear into the invasive species.

The robotic fish is also equipped with "computer vision" so it can spot when the mosquitofish approach tadpoles and swiftly intervene.

Dr. Polverino said: "Instead of killing them one by one, we’re presenting an approach that can inform better strategies to control this global pest.

"We made their worst nightmare become real: a robot that scares the mosquitofish but not the other animals around it.”

Mosquitofish were placed in a testing arena with their 'robotic nemesis' to see how it affected their behavior.

The fish tended to stay closer together, spend more time at the center of the arena and were hesitant to tread uncharted waters.

They also swam more 'frantically,' regularly making sharp turns, compared to those who had not yet met the robot.

Even after they had been taken out of the tank and placed back in their own aquarium, the fish showed signs of being afraid.

The jittery fish showed signs of anxiety for weeks after coming face to face with the robot, including being less active, eating more and freezing for longer.

But the tadpoles on the other hand did not 'break a sweat', as unlike the mosquito fish, they have bad eyesight and could not see the predator robot.

In fact, with the mosquito fish out of the way, they were more willing to venture into the middle of the arena.

Dr. Polverino said: “We expected the robot to have neutral effects on the tadpoles, but that wasn’t the case.

"It turned out to be a positive thing for tadpoles.

"Once freed from the danger of having mosquitofish around, they were not scared anymore.

"They’re happy.”

After five weeks, the mosquito fish began spending more time and energy escaping the robot than reproducing, the researchers found.

The males became thin and streamlined, with stronger tail muscles designed to cut through the water when fleeing.

They also had lower sperm counts, while females produced lighter eggs, changes which could compromise the species’ survival as a whole.

Senior author Dr. Maurizio Porfiri at New York University said: "While successful at thwarting mosquitofish, the lab-grown robotic fish is not ready to be released into the wild."

Next, the researchers are planning on testing their robot on small, clear pools in Australia, where two endangered fish are threatened by mosquitofish.

Dr. Polverino said: “Invasive species are a huge problem worldwide and are the second cause for the loss of biodiversity.

"Hopefully, our approach of using robotics to reveal the weaknesses of an incredibly successful pest will open the door to improve our biocontrol practices and combat invasive species.

"We are very excited about this.”

The findings were published in the journal iScience.