In a world hungry for nutritious food, aquaculture is clearly a winning idea.
It isn’t a new one, either. Humans have been farming seafood for millennia. In more recent years, aquaculture has expanded to land-based tanks, where farmers raise fish and other seafood. Those tanks, however, take up increasingly valuable space on land and worsen competition for scarce water and other supplies.
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This has more farmers looking back to the sea, where space is abundant and water and nutrients are free. Mariculture, the subset of aquaculture in the open seas, however, presents additional challenges.
A UAE tradition
Robotics could be on tap to move traditional Emirati fishing techniques into the future. Read more›››
The robots Lakmal Seneviratne and his team are working on at Khalifa University could eventually be employed to clean and repair hadra – fence traps placed perpendicular to shore – and gargour – fishing traps woven from palm leaves into a semicircular form, he says. ‹‹‹ Read less
Traditional mariculture relies on intensive manual labor to clean and repair equipment, monitor conditions, inspect nets and care for the plants and animals raised for human markets. That kind of manual labor is expensive, requiring trained commercial divers who are increasingly spread thin as aquaculture operations expand. It can also be dangerous work for those divers, particularly as farms move out into deeper and more perilous waters.
Mariculture can also pose threats for the environment, spreading disease, antibiotics and parasites or allowing farmed fish to escape and negatively affect native species.
Eleni Kelasidi, a senior researcher at SINTEF, one of Europe’s largest independent research organizations, thinks those issues could have a common solution: robots.
Putting a robot into the open water can be a bigger challenge, however, than putting a robot on the land.
For one thing, Kelasidi says, it’s important that autonomous systems do not harm farmed fish and/or damage the flexible structures.
This is both an ethical and economic consideration, she says. The ethical consideration: “We cannot harm any living thing and/or let them to escape from the fish farms.” The economic: “The fish are the profit of the industry.”
Happy fish
Kelasidi and her team have access to industrial scale fish farms and operate full scale research facility to investigate how robots stress or otherwise affect fish using equipment originally designed for the oil and gas industry. They test systems to see how well they function but also to observe how fish react to, say, different colors, sounds or lights. The goal is to learn what stresses fish and ensure healthier fish stocks and better profits.
Humans on the surface currently perform many aquaculture jobs using remotely operated machines, she notes.
“Our job is to cut the dependence from the humans to get the robotic systems to operate themselves. They need to understand their environment and make sure they don’t collide with structures,” Kelasidi says.
Another challenge for researchers, she says: making remote-operating vehicles “more clever.”
‘An exciting frontier’
Self-operating aquatic systems is an issue Lakmal Seneviratne, director of the Center for Robotics and Autonomous Systems at Khalifa University, is working on as well, and he’s optimistic.
CAPTION: Aquabots from Khalifa University“It’s a very exciting frontier in underwater robotics,” he says, noting that 70 percent of the Earth is water but humans have explored only 5 percent of that.
Seneviratne and his team are also working on land-based agricultural robots such as “dogs” that can step lightly between rows of crops; “hands” that can gently pick fragile fruits; and robots on rails that can move up and down a field to monitor individual plants for signs of disease or readiness for harvest.
But ocean farms present a different set of challenges for autonomous systems.
“The problem isn’t that aquaculture is very deep, but (maintaining) navigation and control,” Seneviratne says, echoing Kelasidi’s concerns.
GPS doesn’t work beneath the water’s surface and robots have to be able to navigate currents and waves without damaging each other or farm structures.
Cameras, to capture images, and artificial intelligence, to sharpen and analyze those images, are important to managing these conditions, he says.
Looking to nature
But being able to see in the murky depths is only part of the issue for mariculture robotics. The machines also need control. So researchers are looking at life forms already adapted to aquatic environments for inspiration. Although not specifically designed for aquaculture, the biomimicry could prove useful in ocean farms. Among the ideas:
Aquaculture’s promise and challenges
As the world’s population grows and climate change puts more pressure on traditional terrestrial farming, sustainable aquaculture could play a key role, says Naveed Nabi, an assistant professor at Chandigarh University. Read more›››
“In the present times, when food security is a matter of serious concern, aquaculture has played a key role to mitigate this crisis, supplying about 178 million tons of food in which 20.2 kg per capita is destined for human consumption,” he says. “Aquaculture not only adds resilience to the global food system through improving resource-use efficiencies, but also by diversifying the farmed species.”
But he warns that farmed fish present challenges to the environment including fish escapees that harm native species and the spread of disease and parasites.
There’s also the issues of eutrophication, in which water becomes overloaded with nutrients, leading to deadly algae blooms; antibiotics in the environment through unconsumed food or fish waste; and threats associated with pesticides. ‹‹‹ Read less
A team from Harvard and the University of South Carolina in 2021 presented the Finbot, which uses four independently controllable fins.
In 2023, a team from Zhejiang University, China, in 2023 published results of their Copebot, designed to mimic the copepod, a small crustacean known to escape from predators with explosive jumps. Their bot, they report, was able to leap out of the water, land on a small pad, transmit data and jump back into the water.
Back at Khalifa University, meanwhile, researchers have other ideas.
“Looking at aquatic environments, many animals evolved flexible or completely soft bodies to improve their swimming capability and adaptability to the intricate underwater world,” says Federico Renda, who heads the team. “For instance, octopuses can squeeze into small apertures to hide or catch prey, and jellyfish developed the most efficient locomotion strategy of all. In my team, we take inspiration from soft creatures to build new underwater robots capable of replicating these functionalities while understanding the physical principles involved.”
One of KU’s designs mimics flagella, the whiplike structures that propel bacteria through liquid to solve another issue with underwater robots: Many are tethered. While the tethers allow the machines to be operated from the surface, they can also become tangled together.
“Recently, we have developed an untethered underwater robot inspired by flagellate microorganisms capable of efficient and safe locomotion in close proximity to sensible underwater habitats,” Renda says. “Furthermore, each flagellum can be used as a coiling gripper in addition to propulsion, achieving redundancy and multifunctionality, which can significantly simplify underwater operations.”
To test robots’ ability to navigate choppy waters, Khalifa University built a wave pool that simulates currents. Stanford University’s Oussama Khatib recently used it to run Ocean One, a humanoid robot designed to perform such tasks as monitor coral reefs and offshore oil rigs, through its paces.
SINTEF’s Kelasidi would like to see robots replace human divers or assist them on highly risky operations. Seneviratne likewise expects robots to allow human divers to inspect more often and longer.
“We see robots as helping divers instead of replacing them,” he says.
