While ocean-based fish farms do help take pressure off of wild stocks, they have eco-unfriendly drawbacks of their own. A new underwater robot is being designed to address that situation, by autonomously inspecting the fish and their pens.
Among the potential problems with marine aquaculture operations are the facts that non-native fish may escape and upset the local ecological balance; the farmed fish may spread viruses or bacterial infections to their wild counterparts; and the farms may produce high concentrations of fish excrement that pollute the surrounding environment.
In order to keep such problems at bay, many operations utilize human divers to periodically inspect the nets for holes, and to check the fish for signs of disease. Water quality sensors may also be installed within the pens.
Unfortunately, though, the presence of the divers can be upsetting and stressful to the fish – plus the inspections are time- and energy-consuming for the divers to perform. Additionally, because the sensors are usually just installed in one part of the pen, they may not provide an accurate picture of the water quality in other areas of the enclosure.
That's where the CageReporter robot is intended to come in.
Currently being developed by a team at Norway's SINTEF research institute, it's designed to autonomously work its way around fish pens, keeping track of where it is using a proprietary underwater positioning system. It's also equipped with a 3D computer vision system, which it uses to check the conditions of both the netting and the fish themselves. The robot additionally utilizes artificial intelligence-based algorithms to observe the behaviour of the fish, adjusting its movements in order to disturb them as little as possible.
As it travels and inspects, CageReporter uses onboard sensors to measure the water's temperature, oxygen levels and light levels – a drop in the latter could indicate that a high concentration of suspended waste particles are present. Should any problems with the net, fish or water quality be detected, the robot relays its location to a surface-located base station via ultrasound pulses that it transmits through the water.
A prototype has already been successfully field tested at two aquaculture facilities located off the coast of the Norwegian city of Trondheim.
"Vehicles like this can collect useful data, making it more precise and more objective than the data we can collect as humans," says project leader Eleni Kelasidi. "Thus, the technology gives us incredibly precise and important information on, for example, the fish’s health and the quality of the water in real time […] In the future, we might even be looking at completely un-manned aquaculture facilities."
Another Norwegian team is developing a different fish farm-monitoring robot, that helps put fish at ease by swimming like a sea turtle.
Source: SINTEF
