How does Robots use fear against invasive fish?

invasive fish

Basic Concept
The invasive mosquitofish (Gambusia holbrooki) bites off the tails of freshwater fishes and tadpoles, causing the native species to die while feasting on the eggs of other fishes and amphibians. Researchers designed a robot to scare mosquitofish away in a study published December 16 in the journal iScience, demonstrating how fear modifies its behavior, physiology, and fertility – and may help reverse the tide against invasive species.
Explanation
To combat the invasive fish, the multinational team of scientists and engineers from Australia, the United States, and Italy looked to its natural predator, the largemouth bass (Micropterus salmoides). They created a robotic fish that imitates the appearance and motions of a genuine predator. The robot uses computer vision to strike mosquitofish when they approach tadpoles of an Australian species (Litoria moorei), which is threatened by mosquitofish in the wild. Scared and disturbed, the mosquitofish exhibited apprehensive behaviors, as well as weight loss, changes in body form, and a decrease in fertility, all of which hampered their survival and reproduction.
“Mosquitofish is one of the world’s 100 worst invasive species, and current elimination tactics are too expensive and time-consuming to properly resist its expansion”, says first author of the University of Western Australia, Mr. Giovanni Polverino. “A wild range of aquatic animal’s life is in a serious threat due to this global pest. Instead of killing them one by one, we propose a method that can help guide improved tactics for controlling this widespread problem. We made their worst nightmare come true: a robot that frightened mosquitofish but no other creatures.”
In the presence of the artificial fish, mosquitofish tended to cluster closer together and spend more time in the middle of the testing arena, unwilling to go into unfamiliar territory. They also swam faster, with more frequent and acute turns, than those who hadn’t met the robot. The effect of dread continued while they were away from the robot and back in their own aquaria. The terrified fish were less active, ate more, and froze for longer periods of time, displaying signals of worry that lasted for weeks after their last interaction with the robot.
The presence of the robot was a positive shift for the tadpoles that the mosquitofish normally feast on. While the mosquitofish is a visual species that investigates its surroundings primarily with its eyes, tadpoles have weak eyesight and cannot see the robot properly. “We anticipated the robot to have no influence on the tadpoles, but that wasn’t the case”, Polverino explains. Because the robot altered the mosquitofish’s behavior, the tadpoles no longer had predators on their tails and were more ready to go out into the testing area. “It turned out to be beneficial to tadpoles. They were no longer afraid after being emancipated from the threat of mosquitofish. They’re pleased.”
After five weeks of short contacts between the mosquitofish and the robot, the researchers discovered that the fish spent more energy fleeing than breeding. Male fish developed slim, streamlined bodies with stronger muscles towards the tail, allowing them to cut through the water while escaping. Male fish exhibited lower sperm counts, while females produced lighter eggs, both of which are alterations that are likely to jeopardize the specie’s overall survival.
“While the lab-grown robotic fish was successful in preventing mosquitofish, it was not ready to be discharged into the wild”, explains senior scientist Maurizio Porfiri of New York University. The squad will still face technological difficulties. As a first step, scientists intend to test the approach in small, clean pools in Australia, where mosquitofish pose a threat to two endangered fish.
“Invasive species are a significant concern all across the world, and they are the second leading source of biodiversity loss”, Polverino explains. “Our technique of using robots to uncover the faults of an incredibly successful pest will pave the road for us to improve our biocontrol processes and combat invasive species, hopefully”, said by Polverino.

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