Lerøy testing project to detect salmon health with implanted sensors

Farmed salmon company Lerøy Seafood Group has launched a pilot project in Norway that would attach sensors directly to the bodies of salmon in cages, then use an underwater wireless network to capture data in real time from the sensors about fish behavior and transmit it to farm managers on the water’s surface.

The technology would be a major advance from current monitoring systems, which can’t directly measure fish health in the water, and would give salmon farmers the kind of detailed information about the fish in their cages that so far has eluded them.

“Today we are using underwater cameras and monitoring by eye how the fish are behaving. And in many cases this is like looking into a room through the keyhole of a door. You see just a small part of what’s going on in the cage,” Harald Sveier, a technical manager at Lerøy, told SeafoodSource. The new technology “will give us an opportunity to optimize production, where we have more online measurements on the fish, not only judging what we can see with the eye but what we can sense.”

Ultimately, Lerøy wants to be able to plant electrodes and other sensors on a certain number of indicator fish – perhaps 20 – out of the 200,000 or more in the cage, then monitor these fish online, tracking their swimming speed, stress levels, feeding behavior, and other activities, Sveier said.

To be successful, the project will have to overcome a series of technological hurdles.

It will have to work properly amidst all the noise of the sea, such as boats passing, and even the noise of the fish themselves. The signals also can’t be blocked by the bodies of the fish, especially with so many in the cage. The sensors and electrodes on the fish can’t affect or interfere with fish behavior, and those fish with sensors have to be sorted from the rest before processing so electronics-implanted fish aren’t shipped to customers.

Currently, the first underwater network is up and running in the ocean, while electrodes are now being tested on fish in tanks. Sveier expects the project to be finished within two years.

For the project, Lerøy has partnered with technology company WSense, which has a background in the defense industry, the energy sector and environmental monitoring but has recently moved into aquaculture. WSense is seeking to bring Internet of Things (IoT) technology to the ocean, by creating an Internet of Underwater Things (IoUT) for aquaculture operations.

On land, farmers have embraced IoT technology, with wireless sensors that collect information about soil conditions, temperature, humidity, and other factors – data that is then fed into software programs that produce sleek visualizations and, even, recommendations for action.

On land, "you have the possibility to monitor almost everything around you with devices that are low cost," Chiara Petrioli, the R&D director at WSense, told SeafoodSource. "If you go to the underwater world, this is far from being true. What we have are large, complex legacy systems that are often cabled."

In August at Aqua Nor 2019, WSense presented its core technology of nodes that can be used for on-cage wireless sensing infrastructure. The nodes communicate with commercially available probes that measure salinity and other water conditions, along with the sensors on the fish themselves.

Typical land-based wireless communication technologies, such as wifi and cellular, don't transmit under the waves, so WSense uses acoustic technology arrayed in a mesh network, converting wireless signals traveling above the water into acoustic signals that can be transmitted underwater. A gateway buoy acts as a bridge between the underwater and terrestrial domains.

The underwater transmitting frequencies are higher than what salmon can hear, so will not affect the fish, according to WSense. The nodes and probes can be placed at different depths and locations inside, outside, and on the cage; the casing is being designed to ensure easy deployment and smooth battery replacement.

WSense also has a software platform, available in both a cloud and standalone version, called WGate to manage the system – integrating, analyzing, and visualizing the data. The fish health sensors will be able to collect information directly from the fish on their health, monitoring them remotely, in real time, all while gathering relevant data for accurate risk assessment forecasting. The miniaturized sensors could be available as soon as a few months, Petrioli said.

"We are able to finally get the data directly from the fish and different nets and different locations on the cage," Petrioli said.  

Photo courtesy of Lerøy Seafood Group