Invasive Fish May Get Their Own Dystopian Nightmare

CC BY 2.0. The research team designed a robot that mimicked a predator largemouth bass in appearance and swimming motions. NYU Tandon / Mert Karakaya

Scientists find that scary fish robots can quickly stress invasive fish species into reduced reproduction.

I always feel conflicted when talking about invasive species. They are so destructive that schemes to hasten their demise bring on feelings of victory. And then I feel guilty for feeling glee – it's not their fault they are invasive species – and then I feel happy for the native species, and then ... repeat.

But the bottom line is this: No matter how much empathy one might have for all the animals, invasive species really can not be tolerated. They steamroll ecosystems and make a mess out of everything; by their very nature, the most successful ones are the hardest to control. And in bodies of water, they prove to be especially slippery, so to speak, because native fish and other wildlife have few means of escape.

With this in mind, NYU Tandon School of Engineering's Maurizio Porfiri teamed up with researchers from University of Western Australia to explore whether or not robotic fish could be employed in the battle against one of the world’s most problematic invasive species, the mosquitofish.

"Found in freshwater lakes and rivers worldwide, soaring mosquitofish populations have decimated native fish and amphibian populations, and attempts to control the species through toxicants or trapping often fail or cause harm to local wildlife," notes a statement on the research.

In the study, Porfiri and his team experimented to see if a biologically inspired robotic fish could scare mosquitofish into deleterious behavior changes. The robots were created in the likes of a largemouth bass, the mosquitofish's primary predator.

They found that indeed, being exposed to a robotic predator created, meaningful stress responses, "triggering avoidance behaviors and physiological changes associated with the loss of energy reserves, potentially translating into lower rates of reproduction."

(I mean, can you blame them? I'd be stressed out too if big predatory robots were installed in my house.)

“To the best of our knowledge, this is the first study using robots to evoke fear responses in this invasive species,” Porfiri said. “The results show that a robotic fish that closely replicates the swimming patterns and visual appearance of the largemouth bass has a powerful, lasting impact on mosquitofish in the lab setting.”

It is not entirely surprising that they found the fish who had encounters with robots that most closely mimicked the aggressive, attack-poised swimming patterns of their real-life assailants had the highest levels of behavioral and physiological stress responses.

“Further studies are needed to determine if these effects translate to wild populations, but this is a concrete demonstration of the potential of a robotics to solve the mosquitofish problem,” said Giovanni Polverino, Forrest Fellow in the Department of Biological Sciences at the University of Western Australia and the lead author of the paper. “We have a lot more work going on between our schools to establish new, effective tools to combat the spread of invasive species.”

It's an ingenious way to tackle a vexing problem, even if it does have hints of "dystopian nightmare" for invasive fish.

The study, "Behavioural and life-history responses of mosquitofish to biologically inspired and interactive robotic predators," was published in the Journal of the Royal Society Interface.